Clearance in BD plane

[Patrick Chase]

I finally managed to have an honest-to-goodness clearance issue. I've been playing with low-angle frogs in a couple of my smoothers, and had a 40-deg one in my LV custom 4-1/2 last week.

I swapped a new blade in while working some Red Alder with a medium cut (several mils, I didn't measure), and promptly had cutting issues. Swapping to a different, equally sharp blade with a lower bevel fixed them. When I went and looked at my spreadsheet (I know, laugh away) I discovered that I'd grabbed the wrong spare blade, and the one I'd used was set up with a 35 deg secondary bevel. Just for kicks I tried the problem blade on some Sugar Maple and Yellow Birch scraps (both about 1.5X as hard as the Alder) and didn't see issues.

So here's one empirical result for the endless clearance debate: 5 deg is low enough to start to cause trouble on a fairly soft hardwood (~1.3 mpsi modulus).

The reason I'm posting this is because I'm firmly of the opinion that extra clearance is nothing more than wasted blade life, so it pays to know where the real limits are. I think it's good to have some margin, so I'm going to continue to aim for ~10 deg clearance.

[bridger berdel]

Extra clearance being wasted blade life would be entirely dependent on your sharpening practice, says I. I hog out the primary bevel on a grinder and hone freehand. I aim for minimal clearance for a stronger edge, which may be what you meant....

[Warren Mickley]

There is another issue that a higher cutting angle makes for a more stress on the cutting edge, more shear stress. Scraping with a chisel is harder on the edge than paring at a low angle.

I did extensive tests on clearance forty years ago. Eight degrees is where I started noticing definite problems with clearance, although I would expect some variation for different timbers. At small clearance angles the plane might show
problems from dulling earlier.

[Patrick Chase]

Extra clearance being wasted blade life would be entirely dependent on your sharpening practice, says I. I hog out the primary bevel on a grinder and hone freehand. I aim for minimal clearance for a stronger edge, which may be what you meant....

That's exactly right. When I said "wasted blade life" I was referring to the impact of additional sharpening due to faster-than-necessary edge dulling. IMO that's true no matter what sharpening process you use.

Both clearance and edge life are determined by the bevel immediately behind the cutting edge, which I'll call "tip bevel" from here on
. In my experience going from, say, 25 to 35 deg tip bevel in a common-pitch plane (45 deg bed) has no effect on clearance, but a big impact on edge durability and life.


I've seen some people argue that the primary or overall bevel matters for clearance, but that can be disproven by one simple observation: For almost any reasonable blade geometry, the primary bevel will be entirely above the plane of the sole.

[Patrick Chase]

There is another issue that a higher cutting angle makes for a more stress on the cutting edge, more shear stress. Scraping with a chisel is harder on the edge than paring at a low angle.

I did extensive tests on clearance forty years ago. Eight degrees is where I started noticing definite problems with clearance, although I would expect some variation for different timbers. At small clearance angles the plane might show problems from dulling earlier.

I've adopted your view w.r.t. cutting angle - that's one of the reasons I'm playing with lower-angled frogs right now.

My comment about clearance and blade life assumed constant cutting angle and therefore constant stress. IMO we should always try for the minimum practical clearance angle, as that gives the highest edge angle and durability. I'm glad to see that I'm in the right ballpark :-).

[Normand Leblanc]

A blade appear dull when I have to add pressure on the toe. This happens because there is a flat being created under the blade. What we should be interested in is to reduce the surface of that flat as much as we can. Obviously a very large relief angle would be the solution but the edge would be fragile.

To calculate that surface, knowing that the width is constant, the relation would approx. be: 1/tanθ. Theta is the relief angle.
Angle: surface
15, 3.7
12, 4.7
9 , 6.3

This means that a 15 degree relief angle will develop a flat but it's size will be much smaller than with a 9 degree RA. This is an approximation but should be in the ballpark. With a high RA you need to have more wear to get to an equal surface as a low RA.

I did a test (I'll post that soon) where a plane is used with different relief angle (same wood, same sharpening method). I begin planing and, after 5 cuts, then 10, etc. I check if the plane engage a cut without any weight added. I'm pushing the plane by the sole behind the handle. When I can't get the plane to engage the test is complete.

Results for a Stanley blade(relief angle; number of cuts):
15,50
12,35
9,12.5

12.5 is the result of two test because I could not believe that I was only getting 15 cuts. Made another one to get only 10.

This kind of result tells me that the edges of our BU planes do not last as long as our BD planes (I should say that the BU planes, because of their relief angle, do not last as long as a BD). Again, I've tested that and there is quite a margin between a BD at 12 degree relief and a BU at 15 degree.

[Luke Dupont]

By clearance, I assume you mean the difference in angle between the angle which the iron is bedded at, and the angle which the bevel is sharpened at?

I had some odd clearance issues with my Japanese plane once - it's bedded a little lower than standard western irons, at around 41 degrees. And I suppose I was sharpening the bevel around 30-35 degrees free hand - I wasn't really measuring. As a result, I had some weird behavior where the plane ceased to cut well, acting as if it were dull after a short period of time. I'll bet the very edge was getting rolled slightly back into the plane after working with hardwoods, resulting in the plane riding the bevel - especially noticed this problem on rough sawn timber or uneven surfaces.

I reshaped the bevel at a lower angle, about 25-30 degrees, and haven't had any issues since.

[Patrick Chase]

A blade appear dull when I have to add pressure on the toe. This happens because there is a flat being created under the blade. What we should be interested in is to reduce the surface of that flat as much as we can. Obviously a very large relief angle would be the solution but the edge would be fragile.

To calculate that surface, knowing that the width is constant, the relation would approx. be: 1/tanθ. Theta is the relief angle.
Angle: surface
15, 3.7
12, 4.7
9 , 6.3

This means that a 15 degree relief angle will develop a flat but it's size will be much smaller than with a 9 degree RA. This is an approximation but should be in the ballpark. With a high RA you need to have more wear to get to an equal surface as a low RA.

I did a test (I'll post that soon) where a plane is used with different relief angle (same wood, same sharpening method). I begin planing and, after 5 cuts, then 10, etc. I check if the plane engage a cut without any weight added. I'm pushing the plane by the sole behind the handle. When I can't get the plane to engage the test is complete.

Results for a Stanley blade(relief angle; number of cuts):
15,50
12,35
9,12.5

12.5 is the result of two test because I could not believe that I was only getting 15 cuts. Made another one to get only 10.

This kind of result tells me that the edges of our BU planes do not last as long as our BD planes (I should say that the BU planes, because of their relief angle, do not last as long as a BD). Again, I've tested that and there is quite a margin between a BD at 12 degree relief and a BU at 15 degree.

All I can say is: I don't get results at all like that. Nor do the many, many, many people successfully using BU planes with 12 deg bed angles. Wear bevels certainly do develop on the blade back near the tip, forcing you to re-flatten the back every so often. That happens over the course of thousands of strokes, though, not 30. There is something extremely unique about your setup, and not in any positive sense of the word.

Is it possible you're dubbing the edge somehow? Are you using non-rigid media (leather or elastomer strop, mdf, etc) at any step in your honing process?

EDIT: I don't suppose you lift the plane when you draw it back?

[bridger berdel]

My first read on your post was that by honing at a lower angle you were removing more metal and that was the source of reduced blade life. Which sort of makes sense, until you examine it. As I was finishing my post I realized that that probably wasn't what you meant, but I was out of time, so I sent it as it was.



That's exactly right. When I said "wasted blade life" I was referring to the impact of additional sharpening due to faster-than-necessary edge dulling. IMO that's true no matter what sharpening process you use.

Both clearance and edge life are determined by the bevel immediately behind the cutting edge, which I'll call "tip bevel" from here on
. In my experience going from, say, 25 to 35 deg tip bevel in a common-pitch plane (45 deg bed) has no effect on clearance, but a big impact on edge durability and life.


I've seen some people argue that the primary or overall bevel matters for clearance, but that can be disproven by one simple observation: For almost any reasonable blade geometry, the primary bevel will be entirely above the plane of the sole.

[david charlesworth]

Warren's research makes good sense to me.

I have sharpened all my bevel down, 45 degree pitch, bench planes at 35 degrees for donkey's years, and this works very well.

David

[Kees Heiden]

Steve Elliot looked at the formation of the lower wear bevel, that is the rounded bulge just behind the edge at the underside of the blade. The part touching the wood. This lower wear bevel tends to lift the edge out of the wood, ultimately leading to the feeling that you must sharpen again. Populair believe is that the roundness of the very tip of the edge makes the unsharpness, but Steve's test proves that's not true. The tip quickly looses its very sharp tip and after that the radius of the tip doesn't change much until the edge becomes very very blunt, way beyond fine cabinet making standards. http://bladetest.infillplane.com/html/wear_profiles.html

So, the wear bevel at the clearance side of the blade is what makes the tool feel dull. It would be reasonable to think there is a correlation between clearance angle and the formation of this lower wear bevel. But I don't know of any study specifically adressing this issue. I did stumble across something though when I did my tests to compare high cutting angles to chipbreakers. The article is here: http://planetuning.infillplane.com/html/mechanics_of_chipbreakers.html

The second part of this study was about the wear behaviour. I meassured the horizontal force (pushing the plane) and the vertical force (the pressure of the edge against the shaving) Especially the vertical force is interesting in this case because it represents the effect of this wear bevel. When the blade is sharp this force is ideally negative, meaning the edge is pulled into the wood. Wear makes it less negative or even positive, meaning the edge is more and more pushed out of the wood, neccessitating us to press harder on top of the plane (or sharpen the blade).

337878

Now, I first did my tests with a 60 degree plane with only a 15 degree clearance angle. I saw that the vertical force increased faster then my 45 degree planes. Don Willans complained about this, saying that was not enough clearance. I repeated the test with a 30 degree clearance angle, and behold, the wear rate was a lot better! (Still, not quite as good as the chipbreaker plane of course ;-))

My conclusion: High cutting angles and low clearance angle are not an ideal combination. This of course still prooves not much about planes with a standard cutting angle.

[Kees Heiden]

Normand, I think your test is a good effort to find a correlation between clearance angle and wear bevel. The effect you see is exactly what I was measuring with the vertical force sensors, an increase of wear at the clearance side diminishes the ability of the edge to pull itself into the wood. Of course, this is a limited test and therefore still open to debate.

And Patrick, he was looking at how often he could raise a shaving without any additional pressure on the plane, except the weight of the plane itself. In real use you always exert some pressure, increasing that pressure as the blade gets duller and duller. So you can milk out a lot more plane strokes.

[Stewie Simpson]

Warren's research makes good sense to me.

I have sharpened all my bevel down, 45 degree pitch, bench planes at 35 degrees for donkey's years, and this works very well.

David

David; based on a minimum clearance of 10*; I am not understanding why you would have a starting point of 35* on a bevel down plane pitched at 45*.

Stewie;

[Pat Barry]

.... When I went and looked at my spreadsheet (I know, laugh away) I discovered that I'd grabbed the wrong spare blade, and the one I'd used was set up with a 35 deg secondary bevel. .
ROFL... Seriously man, you have far too many tools if you can't keep track of them without a spreadsheet.

[david charlesworth]

Stewie,

When I sharpen at 35 degrees, (this is actually just polish at the tip,) Clearance angle is reduced from 15 degrees to 10 degrees.

And it works fine.

David

[Stewie Simpson]

David; thanks for the reply. What is your minimum clearance angle before you regrind the primary.

Stewie;

[Kees Heiden]

There s probably an optimum for the bevel angle, a balance between maximum clearance angle and maximum sharpening angle. For a bevel down plane it is probably between 25 and 35 degrees :D

[Normand Leblanc]

Patrick,
I was using for many years LV BU planes then I got a few Woodriver and finally just a month ago I bought a LN 4-1/2 and I immediately noticed a large difference in edge retention. This noticeable difference got me to make my own little study http://oldchips.blogspot.ca/2016/05/study-edge-retention-of-plane-iron-with.html and the results that I was getting with the BU kept me from publishing until I was able to figure it out.
Yes, the blade was lifted on the way back.
Yes, a strop was used but very lightly with the blade in a sharpening guide.

David,
A 35 degree bevel will work just fine. What I'm saying is a 10 degree RA won't last as long as a 12 or 15 one.

Kees,
Your tests have help me a lot understanding what was going on.

[david charlesworth]

Stewie,

What I have on (almost) all my bench plane blades is, grind 25deg., coarse stone 33deg., polish 35 degrees.

Nice and easy with an Eclipse type jig.

David

And naturally ruler trick for polishing stone on back.

[Stewie Simpson]

Thanks for the feedback David.

Stewie;

[Steve Voigt]

Definitely an interesting topic. I tend to think that Normand (and Kees) are right about the relationship between clearance angle and wear bevel, but I can't say for sure.

One thing I want to point out is that trying to maintain an absolute minimum clearance angle is probably incompatible with the type of "freehand grind the primary, freehand hone the secondary" sharpening method that I and many others use. Most of the time I aim for 25° primary and 30° secondary, but both can vary a couple degrees, so I probably have a total variance of 5° or so. Since my normal clearance angles are probably 12°-17° or so, it's not an issue, but if I were trying to "redline" an 8° clearance angle, it would matter.

My point is that worrying about the ideal angle to maximize blade life, much like worrying about what "wonder steel" will maximize blade life, is only an issue when sharpening is an onerous or overly complicated task. An efficient freehand routine tends to make sharpening a welcome diversion from hard work, and obviates the sort of concerns being discussed here…my $.02, ymmv, and all that.

[Steve Voigt]

There s probably an optimum for the bevel angle, a balance between maximum clearance angle and maximum sharpening angle. For a bevel down plane it is probably between 25 and 35 degrees :D


A revelation! Who knew? :p

[Normand Leblanc]

My point is that worrying about the ideal angle to maximize blade life, much like worrying about what "wonder steel" will maximize blade life, is only an issue when sharpening is an onerous or overly complicated task. An efficient freehand routine tends to make sharpening a welcome diversion from hard work, and obviates the sort of concerns being discussed here…my $.02, ymmv, and all that.
Sure! I hand sharpen and it's very quick but if I know that the angle I'm getting is causing a problem then I will change my procedure. In this case all I have to do is to have a few more degrees of RA and my blade will last much longer.

[Steve Voigt]

When I went and looked at my spreadsheet (I know, laugh away) I discovered that I'd grabbed the wrong spare blade, and the one I'd used was set up with a 35 deg secondary bevel.

I'm not laughing; I think there is an issue generally with folks who have busy lives and can only squeeze in a couple hours of shop time a week. It's easy to lose track of where you are if you haven't picked up a plane in a few days, and you waste a lot of time just retracing your steps.

I'd suggest, however, that the solution for folks in that predicament is to go in the opposite direction and simplify. I basically do all of my bench planing with three planes. I might make that four if I start using a shooting plane more regularly. I have no spare blades. And I sharpen all but the shooter at the same angle. I spend a lot of hours in the shop, but even if I didn't it would be easy to keep track of this limited information.

More importantly, as Warren Mickley has pointed out many times, there is a fluency and a familiarity that comes with working with (and mastering) a very limited set of tools.

(not that you (the OP) necessarily want or need my advice, but I imagine lots of folks out there can relate to the problem, even if they don't use spreadsheets…)

[Jim Koepke]

More importantly, as Warren Mickley has pointed out many times, there is a fluency and a familiarity that comes with working with (and mastering) a very limited set of tools.

This is one advantage in the column for the minimalist among us. Learning to do more with less is a great tradition.

In the other column resides the person who can not turn down a bargain on an old tool. At least then when something doesn't work they know where lies the fault.

A better way is to master the tools as you acquire them and continue to learn as your tool accumulation grows.

One example would be the Stanley #55. Many think of it as a useless 'boat anchor.' Some, myself included, suggest one fully master the Stanley #45 before attempting to move up to the #55. The #45 can be a bear to get set and working right. Once one can get it to work reliably the #55 isn't as difficult a challenge to conquer.

jtk

[steven c newman]

Hmm....mine are sharpened as a single bevel @25 degrees. never messed with all the other bevels....haven't the time, when honing up a blade to mess with more than one bevel

337892
Stanley No. 5, type 17. OEM blade, sharpened @25 degrees, single bevel. Cutting through pine knots as well as just pine. Chipbreaker set 2mm back from edge. bevel down as designed. It does make a mess on the floor, though..
337893
means I have to sweep the floor..again..since I had fired Igor for not sweeping up.

[Brian Holcombe]

Sometimes it seems like the more time you spend in the shop the less you want to spend thinking about how you setup such and such planes. So you don't want four finishers, etc, you want one.

For guys who don't spend a lot of time in the shop I think they should take apart their planes every day, sharpen and reset until it is such a redundant task that they can set them in the dark.

For or more it's more than three bench planes but only because I refuse to sell the one I don't use.

[Jim Koepke]

As with many things in life there is a point of diminishing returns. The bevel angle on a bevel down plane is another.

We know there must be some clearance angle behind the edge of the blade. If close attention is paid to the video by professors Kato and Kawai it is clearly seen there is some rebound in the wood after the edge passes.

As the edge wears the clearance angle is reduced.

Normand Leblanc points out the failure due to wear determined by actual use.

After all is said and done, my blades will likely not see any changes to what has been working for years.

If someone is happy with what they are using, it is an uphill battle to get them to change.

jtk

[Jim Koepke]

For or more it's more than three bench planes but only because I refuse to sell the one I don't use.

It can always be sold tomorrow, though once it is gone, it is gone forever.

jtk

[Steve Voigt]

Sometimes it seems like the more time you spend in the shop the less you want to spend thinking about how you setup such and such planes. So you don't want four finishers, etc, you want one.

For guys who don't spend a lot of time in the shop I think they should take apart their planes every day, sharpen and reset until it is such a redundant task that they can set them in the dark.

For or more it's more than three bench planes but only because I refuse to sell the one I don't use.


Just to be clear, I too have a lot of bench planes. Partly it's an occupational hazard, but I also have Stanleys 3-7, a bunch of old woodies, and if someone offered me a mint Bedrock right now, I wouldn't say no. The issue, though, is not how many planes you own, but how many do you use day in, day out. On that, I'm pretty sure we agree.

[Brian Holcombe]

Jim Exactly, It comes in handy on occasion. I've turned over chisels and saws without regret but the shipping prices make it fairly expensive to turn over larger things.

Back to clearance angle, I've only found it to be an issue with a 38 degree bed and attempting to take super thin shavings. Not something I do except on show faces so I don't mind sharpening often.

Steve that's where I am at as well, I really only use the Jack, try and LN 4 on the regular. I'll probably make my LN 7 redundant soon enough I'm tired of shooting with a 10lb plane, I will replace it with a long Kanna.

I also tend to stick with steel that can all be sharpened by the same stones as well.... Or at least I'm heading in that direction.

[Patrick Chase]

a
Steve Elliot looked at the formation of the lower wear bevel, that is the rounded bulge just behind the edge at the underside of the blade. The part touching the wood. This lower wear bevel tends to lift the edge out of the wood, ultimately leading to the feeling that you must sharpen again. Populair believe is that the roundness of the very tip of the edge makes the unsharpness, but Steve's test proves that's not true. The tip quickly looses its very sharp tip and after that the radius of the tip doesn't change much until the edge becomes very very blunt, way beyond fine cabinet making standards. http://bladetest.infillplane.com/html/wear_profiles.html

So, the wear bevel at the clearance side of the blade is what makes the tool feel dull. It would be reasonable to think there is a correlation between clearance angle and the formation of this lower wear bevel. But I don't know of any study specifically adressing this issue. I did stumble across something though when I did my tests to compare high cutting angles to chipbreakers. The article is here: http://planetuning.infillplane.com/html/mechanics_of_chipbreakers.html

The second part of this study was about the wear behaviour. I meassured the horizontal force (pushing the plane) and the vertical force (the pressure of the edge against the shaving) Especially the vertical force is interesting in this case because it represents the effect of this wear bevel. When the blade is sharp this force is ideally negative, meaning the edge is pulled into the wood. Wear makes it less negative or even positive, meaning the edge is more and more pushed out of the wood, neccessitating us to press harder on top of the plane (or sharpen the blade).

337878

Now, I first did my tests with a 60 degree plane with only a 15 degree clearance angle. I saw that the vertical force increased faster then my 45 degree planes. Don Willans complained about this, saying that was not enough clearance. I repeated the test with a 30 degree clearance angle, and behold, the wear rate was a lot better! (Still, not quite as good as the chipbreaker plane of course ;-))

My conclusion: High cutting angles and low clearance angle are not an ideal combination. This of course still prooves not much about planes with a standard cutting angle.

I can buy this. At 60 deg cutting angle you already have a reasonably beefy edge even with the higher clearance, so you may be seeing diminishing returns in terms of edge life from increased tip angle, and at that point other concerns will dominate. FWIW I usually don't go higher than 40 deg (or even 35 most of the time) on my BD blades for that reason, even when used in planes with high bed angles - it just isn't worth the hassle.

Note however that the low-clearance configuration *started* with higher cutting force than the high-clearance one, and the difference between the two was fairly constant after the first 25 m of cutting. To me that suggests that wear bevel formation is not the sole cause (and probably not even the principal cause) of the difference. If it were wear bevel related they should have started at the same force, and the low-clearance configuration should get worse with increasing distance. Also note that even at 100m the increase in cutting force is on the order of 20% - Even if that were due entirely to wear bevel formation I'd personally consider it a good tradeoff in exchange for the better chip resistance etc from higher tip angle.

To be clear, I don't disagree that wear bevels form and that they cause the edge profile to change as in the article you linked. What I'm not convinced of is the link to clearance angle. It isn't unequivocally supported by your data for the reason given above. Also, if you think about the mechanics of clearance-face wear, it's fairly likely that it may initially be worse at *high* clearance angles (think about the normal pressure on the wear patch as it starts to grow).

EDIT: Thinking about this some more, it makes sense that high-angle blades would require more initial clearance. The cutting mechanics have more of a "scraping" character and as a result the component of the cutting force that compresses the wood will be higher. More compression -> more rebound -> requires more initial clearance. That explanation seems more consistent with your data (particularly the fact that the 15 deg configuration required higher cutting force at the start, before any wear had occurred) than is wear bevel formation.

[Patrick Chase]

ROFL... Seriously man, you have far too many tools if you can't keep track of them without a spreadsheet.

I don't track tools, I track blades. I don't like to break for sharpening, so I have a fair number of spare blades. It used to be that I only had to track the BU ones since all the BD were either identical or different in obvious ways (camber etc). That changed when I started messing with bed angles.

[Patrick Chase]

Yes, a strop was used but very lightly with the blade in a sharpening guide.


That being the case the bevel at the very tip (the first few tenths of an mm that Kees' diagrams focus upon) is likely a couple deg more than you think, and your disastrous results at "9 deg" start to make much more sense.

The fact that you strop with a guide is irrelevant. Dubbing happens because of the compliance of the strop material itself, and that happens no matter how you constrain the blade. The conformance of the leather is roughly proportional to sqrt(force), so stropping lightly doesn't help as much as most people think.

To be clear I don't think there's any problem with stropping, but I think that if you strop then you have to add some clearance to allow for micro-scale edge rounding in exactly the same place where any "wear bevel" would subsequently develop.

[Patrick Chase]

Just to be clear, I too have a lot of bench planes. Partly it's an occupational hazard, but I also have Stanleys 3-7, a bunch of old woodies, and if someone offered me a mint Bedrock right now, I wouldn't say no. The issue, though, is not how many planes you own, but how many do you use day in, day out. On that, I'm pretty sure we agree.

I would never claim that my approach is optimal :-)

[george wilson]

For heaven's sake. You guys can dwell on nothing of importance forever. The real point is: can you USE your tools to make beautiful things. Do you know design? Can you draw(knowing design does not mean you can draw). Can you do accurate work? And several others.

[Brian Holcombe]

George I tend to agree. Steve's thread on gouge marks was Definetly one of the more interesting as of late. I've been considering starting my threads with the design posted first to have that become a topic in and of itself before kicking off the technical aspect of doing.

[Normand Leblanc]

Hummm...You could be right Patrick. I am going to have to figure out another test it seems.
It's quite possible that a RA of 12 degree would become 10 or 11 after stropping but, to invalidate the results that I got, it would require much more dubbing than that. I'm going to check that this week and let you know.

[Patrick Chase]

We know there must be some clearance angle behind the edge of the blade. If close attention is paid to the video by professors Kato and Kawai it is clearly seen there is some rebound in the wood after the edge passes.

As the edge wears the clearance angle is reduced.

I think everybody agrees with the first assertion. Wood is compressible, and the downward component of the cutting force compresses it. You need some clearance to accomodate the resulting rebound, and the only open question is "how much". I think that's why I needed more clearance in Alder than in less compressible woods BTW.

I don't think that wear bevel formation is as simple as reduced clearance angle. If you look at Kees' diagrams (and many others out there) what you actually see is a ~flat wear patch developing behind the edge. It's more "an ever-growing patch of zero clearance" than "reduced clearance". That's why I'm not entirely sold on the link between the initial clearance angle and problems with wear bevel. That flat spot is going to form no matter what angle you start at, so the real question is "does it form faster with lower initial clearance".

[Kees Heiden]

The wear patch increases, not only in length, but also in height. The changing vertical force, measured by lots of scientists, is another sign that this happens. It removes the clearance, so it is not such a far fetched idea that the initial clearance plays a role too. But I don't know how much.

BTW, this being the handtool forum makes it not so strange that we discuss handtool topics.

[Normand Leblanc]

My finest stone is an hard Arkansas and, with that stone and a freshly sharpened blade, my Stanley 5-1/4 don't even make a single cut using only his own weight (goes to show that the stropping is really achieving something). This plane is my lightiest one. For a new test I had to use a heavier plane and it was a Record no.5 with an old Record blade. That blade performed much better than a Stanley blade in another study (60% better than Stanley).

The results for a 0.002" shaving are:



sharp. Angle
Relief angle
# shavings


Test 1
25
20
120


Test 2
28
17
95


Test 3
31
14
90


Test 4
34
11
70


Test 5
37
8
35



So, you were right Patrick. Using the strop was changing the geometry at the tip.

It's interesting to see that 25 degrees is the best angle but the fact that I'm using BC Fir, a soft wood, must help for a low sharpening angle. I do not pretend that this test if perfect but it's giving a clear direction.

[Kees Heiden]

Nice work Norman.

What kind of shavings are you looking for? Just any kind of shaving or real full length and over what length? From your round numbers I understand that it takes a bit of judgement to decide wheter a shaving ios good enough or not.

And indeed I think in pine everything is a bit mellower then in oak for example, but it is much harder to get the plane taking an oak shaving spontaneously, then a pine shaving.

[James Waldron]

George I tend to agree. Steve's thread on gouge marks was Definetly one of the more interesting as of late. I've been considering starting my threads with the design posted first to have that become a topic in and of itself before kicking off the technical aspect of doing.

Please do! And everyone else too! Formal drawings or napkin sketching from the local pub, a look at where you're headed makes much more sense of the joinery you're cutting. And, as well, we all can learn about the choices to be made in the joinery to suit hand work (and why), since there are so many available choices.

[Normand Leblanc]

Kees,
That's what I like with this particular test is the "judgement" portion is kind of small.

Every five shavings the plane is placed in the middle of the board (the whole sole is supported) then I push it very slowly by the sole behind the handle. It is very easy to see if the blade slide or bite. Sometimes I can get an "in between". In this case, what I have done is, take another shaving (like with a no.8 to get as flat a surface as possible), make sure there is no debris and try again. If it's again an "in between", the test is stopped. Only full width shaving are considered ok. There is no length, it bites or not, 1/2" is plenty to make the call.

[Kees Heiden]

That's very interesting! I didn't understand you were taking normal full length shavings first, then do a test without any weight.

You should write this down in an as complete matter as possible and then we could see if we could put it somewhere for reference.

PS: and maybe you should repeat the test, just to be sure.

[Mike Holbrook]

Lately I have been more in Warren and Steve's frame of mind regarding planes. I have been thinking about reducing how many I work with. I find that I generally do better work with my LV, LA Jack. I think the reason has more to do with familiarity over a decade or more rather than it being the absolute best plane in all situations.

I decided to delve into Stanley planes, mostly as an exploration into chip breakers. I was determined to figure out how to get them to perform for me. After I got familiar enough with these planes to use them decently and started using my BU planes again, I figured out I was still better with my BU planes because they just felt more familiar in actual use. Then I tried a Veritas Custom #4. This plane feels familiar, probably due to its low weight\balance, handle options and adjustment system and it has a chip breaker. Maybe Rob at LV knows a thing or two about his customer base and how to transfer them to a new plane design.

I liked the option LV offers to order frogs for their custom planes at custom angles. Reading Derek's thread on his custom #4, I found that he ordered his with a custom 42 degree bevel. He mentions that one of the reasons he did this was an old post from Warren in which he apparently said his favorite, or one of his favorite, Stanley planes had/has a custom 42 degree frog. Being more familiar with BU planes with combined 25-30+12= total 37-42 degree bevels I decided to give the 42 degree frog a try. Derek mentioned that he felt that the chip breaker made it possible to handle more difficult grain with lower angled frogs. A frog that could handle the maximum amount of different grain situations was attractive to me.

I am a little lost in all the numbers above and wonder what the ultimate point might be? Particularly could 42 minus 30 or 12 degrees be a "sweet spot" for BD frogs, sharpening angles? It seems to be working well for me.

The other question I have has to do with grinding 30 degree "hollow" bevels on blades in BD planes. Many people hand hone these hollow ground blades. I suspect one of the reasons it works is honing these blades makes some "degree" of micro bevel. The two sides of the hollow, of course, keep the edge registered to the stone at the correct angle. Maybe it is possible to hand hone a micro bevel this way without resorting to a honing jig? The micro bevel created is certainly very small but I suspect it is also relatively accurate. Honing an accurate, small micro bevel quickly and easily at a reliable, helpful angle may be part of the reason for this methods success.

[Normand Leblanc]

PS: and maybe you should repeat the test, just to be sure.

That's exactly what I had in mind and it doesn't take that long anyway.

[Jim Koepke]

You should write this down in an as complete matter as possible and then we could see if we could put it somewhere for reference.

Maybe we could get one of the moderators to archive it in the Neanderthal wisdom/FAQs.


I am a little lost in all the numbers above and wonder what the ultimate point might be? Particularly could 42 minus 30 or 12 degrees be a "sweet spot" for BD frogs, sharpening angles? It seems to be working well for me.

Mike, I enjoyed reading your musings on the LV Custom planes. I am so used to using a 25º bevel on my planes my thought for a custom frog would be at 37º. 40º would likely be more practical if one were to use a secondary bevel.

jtk

[Normand Leblanc]

Mike,
I do own a LV LA jointer and a Stanley no.7. I'm more comfortable with the LV plane and hardly use the Stanley.

The tests that I have done needs to be reviewed by someone else but, in the mean time, at this stage I would sum it up to this:

- older blades (Stanley as an example gave me 137 shavings) do not last as long as A-2 or PM-V11 where I got 442 shaving. That's quite a gap.
- a RA of 20 degree will outlast 11 degree by 70% approx.

All of this in relatively soft wood. The first test was done using yellow birch and the RA test on BC Fir.

[steven c newman]

Been using this Stanley #5 since it was rehabbed about a month ago. Haven't needed to sharpen it back up, yet....
338036
The board was rough sawn pine, and it is now S4S using that Type 17 plane...been making a lot of shavings lately. too
338037
Don't have the time to waste by only getting see-through shavings......would take all day to do this one board, instead of....10 minutes.

[Mike Holbrook]

Jim, I do tend to muse a good deal. My experiment with Stanley planes did give me a better feel about why people like them. My continuing issue has to do with a mind set regarding blade adjustment systems for these two types of planes. With the Veritas/Norris system I put the plane under my magnifying light and when it looks like it might have moved I stop adjusting. With the Stanley system it feels like I have to turn the wheel for several days before it actually starts to engage.... Ohhk, I may be exercising a little "poetic license".

I like the feel of the Stanley handles, but the hand position is higher than I am use to. I did order my Custom #4 with a traditional handle. I like the LV traditional handle as it feels more like the Stanley but it seems to be designed to be easier to use with a lower grip too.. I totally believe that all of my "issues" with the Stanley planes result from preconceived notions and experience with adjustments\balance that are at opposite extremes. The balance and adjustments are so far apart I can see why many people seem to like one and dislike the other. I am glad to have the Custom LV option as it strikes me as a compromise in quite a few ways.

Normand, thanks for providing the abridged version. The RA is the difference between the frog angle and the angle the blade is sharpend at? The sharpening angle is what throws me. I understand that a micro bevel is part of the sharpened angle. I'm not sure I know how to figure out what the angle of my hollow ground blade with a hand honed microlevel is.

[Jim Koepke]

With the Stanley system it feels like I have to turn the wheel for several days before it actually starts to engage.... Ohhk, I may be exercising a little "poetic license".

The backlash on the old Bailey adjuster is legendary. For adjusting and setting the lateral I usually use a piece of scrap to set everything. With the plane on the scrap it is slowly moved forward while turning the depth adjustment. When it starts to take a shaving the lateral is checked and adjusted as needed. Then the blade can be advance a bit for the desired shaving thickness.

jtk

[Tom Stenzel]

The real point is: can you USE your tools to make beautiful things. Do you know design? Can you draw(knowing design does not mean you can draw). Can you do accurate work? And several others.

Actually, no.

-Tom

[Pat Barry]

The results for a 0.002" shaving are:



sharp. Angle
Relief angle
# shavings


Test 1
25
20
120


Test 2
28
17
95


Test 3
31
14
90


Test 4
34
11
70



Test 5
37
8
35


.
This table makes no sense. How are you measuring these two angles? Got a diagram?

[Normand Leblanc]

There must be a misunderstanding somewhere...

I use a plane with a 45 degree frog then, as Test 1, I sharpen the blade at 25 degree. That leave 20 degree for the relief angle.

[Steve Voigt]

Really interesting results, Normand. Thanks for taking the time to do the test and list the results here.

[Derek Cohen]

Lately I have been more in Warren and Steve's frame of mind regarding planes. I have been thinking about reducing how many I work with. I find that I generally do better work with my LV, LA Jack. I think the reason has more to do with familiarity over a decade or more rather than it being the absolute best plane in all situations.

I decided to delve into Stanley planes, mostly as an exploration into chip breakers. I was determined to figure out how to get them to perform for me. After I got familiar enough with these planes to use them decently and started using my BU planes again, I figured out I was still better with my BU planes because they just felt more familiar in actual use. Then I tried a Veritas Custom #4. This plane feels familiar, probably due to its low weight\balance, handle options and adjustment system and it has a chip breaker. Maybe Rob at LV knows a thing or two about his customer base and how to transfer them to a new plane design.

I liked the option LV offers to order frogs for their custom planes at custom angles. Reading Derek's thread on his custom #4, I found that he ordered his with a custom 42 degree bevel. He mentions that one of the reasons he did this was an old post from Warren in which he apparently said his favorite, or one of his favorite, Stanley planes had/has a custom 42 degree frog. Being more familiar with BU planes with combined 25-30+12= total 37-42 degree bevels I decided to give the 42 degree frog a try. Derek mentioned that he felt that the chip breaker made it possible to handle more difficult grain with lower angled frogs. A frog that could handle the maximum amount of different grain situations was attractive to me.

I am a little lost in all the numbers above and wonder what the ultimate point might be? Particularly could 42 minus 30 or 12 degrees be a "sweet spot" for BD frogs, sharpening angles? It seems to be working well for me.

The other question I have has to do with grinding 30 degree "hollow" bevels on blades in BD planes. Many people hand hone these hollow ground blades. I suspect one of the reasons it works is honing these blades makes some "degree" of micro bevel. The two sides of the hollow, of course, keep the edge registered to the stone at the correct angle. Maybe it is possible to hand hone a micro bevel this way without resorting to a honing jig? The micro bevel created is certainly very small but I suspect it is also relatively accurate. Honing an accurate, small micro bevel quickly and easily at a reliable, helpful angle may be part of the reason for this methods success.

Going a step further than the Custom #4 is my Custom #7. The #4 has a 42 degree frog. The #7 has a 40 degree frog. Both have blades with 30 degree bevels on PM-V11 steel. This leaves a clearance angle of 10 degrees on the #7.

Prior to this #7, my go-to plane for traversing (planing across the grain) was the LV LA Jack with a 25 degree bevel (creating a 37 degree cutting angle, with a 12 degree clearance angle). Now I can plane across the grain with the #7 at a similarly low cutting angle (40 degrees), which produces a smoother surface finish than a plane with a 45 degrees or greater bed/cutting angle.

http://i13.photobucket.com/albums/a262/Derek50/Planes/Planing/1_zpsbvbhzobb.jpg

http://i13.photobucket.com/albums/a262/Derek50/Planes/Planing/2_zps2beoutht.jpg

The chipbreaker means that I could go directly to end grain with the same performance expectation ...

http://i13.photobucket.com/albums/a262/Derek50/Planes/Planing/Planing-end-grain1_zpsksdm6gef.jpg

http://i13.photobucket.com/albums/a262/Derek50/Planes/Planing/Planing-end-grain2_zpsovgyvffe.jpg

I know that planing interlocked face grain would be similarly stress-free.

One size fits all.

Regards from Perth

Derek

[Pat Barry]

There must be a misunderstanding somewhere...

I use a plane with a 45 degree frog then, as Test 1, I sharpen the blade at 25 degree. That leave 20 degree for the relief angle.
Oh, I see it now. Thanks for clarifying. For some crazy reason I was trying to understand some sort of secondary bevel angle as being the relief angle.

So, what do you think is limiting the number of shavings you take with a bevel angle of 34 where you got 70 shavings as compared to 25 degrees where you got 120 shavings. This seems opposite the typical convention of a sharper angle wearing down faster due to less material.

[Jim Koepke]

Oh, I see it now. Thanks for clarifying. For some crazy reason I was trying to understand some sort of secondary bevel angle as being the relief angle.

So, what do you think is limiting the number of shavings you take with a bevel angle of 34 where you got 70 shavings as compared to 25 degrees where you got 120 shavings. This seems opposite the typical convention of a sharper angle wearing down faster due to less material.

It seems it is more a problem of the relief angle diminishing with wear as opposed to a problem of edge wear as the blade dulls.

The actual edge may have deteriorated more at 25º. At 35º the wear reduces the relief angle to the point of not being able to stay in the wood.

jtk

[Patrick Chase]

It seems it is more a problem of the relief angle diminishing with wear as opposed to a problem of edge wear as the blade dulls.

The actual edge may have deteriorated more at 25º. At 35º the wear reduces the relief angle to the point of not being able to stay in the wood.

jtk

Except of course that that's not how it works in reality.

Take a close look at the micrographs Kees posted several updates back. Wear causes a very small (tenths of an mm at most) zone of ZERO clearance to form behind the edge, and it does so regardless of the initial clearance of the blade.

This is actually extremely simple common sense. Imagine taking the corner of a piece of metal to sandpaper at varying angles. If you tilt it at 10 deg the sandpaper will abrade a 10 deg bevel (i.e. zero "clearance") on the corner. If you tilt it at 20 deg, then the sandpaper will abrade a 20 deg bevel (zero "clearance" again) on the corner. Why should blade wear be any different?

Where clearance angle probably does make some difference is in how quickly that flat spot grows. Obviously as you tip the piece of metal further on edge that forces you to abrade away more material for any fixed size of the flat spot. I suspect that benefit is second-order, though.

[Pat Barry]

Except of course that that's not how it works in reality.

Take a close look at the micrographs Kees posted several updates back. Wear causes a very small (tenths of an mm at most) zone of ZERO clearance to form behind the edge, and it does so regardless of the initial clearance of the blade.

This is actually extremely simple common sense. Imagine taking the corner of a piece of metal to sandpaper at varying angles. If you tilt it at 10 deg the sandpaper will abrade a 10 deg bevel (i.e. zero "clearance") on the corner. If you tilt it at 20 deg, then the sandpaper will abrade a 20 deg bevel (zero "clearance" again) on the corner. Why should blade wear be any different?

Where clearance angle probably does make some difference is in how quickly that flat spot grows. Obviously as you tip the piece of metal further on edge that forces you to abrade away more material for any fixed size of the flat spot. I suspect that benefit is second-order, though.
So, with an acute bevel angle (25 for example) as compared to a more obtuse bevel angle (34 for example), all else being equal, the blade edge should not last as long and the number of shavings in this test should be reduced. I don't think the results of the experiment match expectations. The only conclusion is that the test had another variable that affected the results. I don't think a discovery was made with the test either so a repeat test is in order.

[Warren Mickley]

One of the problems with the test is that both the clearance angle and the bevel angle were varied simultaneously. It is difficult to separate which was the dominant factor. And in addition the test was done without the normal downward pressure; it tested only the irons ability to grab hold of the board and take a shaving. I think this would tend to bias the results toward a more acute honing angle, regardless of the clearance angle.

[Jim Koepke]

This is actually extremely simple common sense. Imagine taking the corner of a piece of metal to sandpaper at varying angles. If you tilt it at 10 deg the sandpaper will abrade a 10 deg bevel (i.e. zero "clearance") on the corner. If you tilt it at 20 deg, then the sandpaper will abrade a 20 deg bevel (zero "clearance" again) on the corner. Why should blade wear be any different?

There is a difference between passing a piece of metal over an abrasive and passing a sharp edge over wood. For one, when working a bevel on metal against abrasive there isn't a need for a relief angle. Another is the abrasive sheet is more likely to 'bubble' in front of the metal. In the video by Professors Kato and Kawai it is possible to see the wood being planed actually rebounding behind the cutting edge. I'm not an expert in physics, but it is my guess that this wood rebounding is part of the reason a blade needs to have a relief angle. With a relief angle of 20º there is a lot more room for wear to the bevel and relief angle than with there is with a relief angle of 10º.

It is also likely this will have more effect when one is making light shavings as compared to thick shavings.

One indicator of blade wear is how thin of a shaving the blade can make.

jtk

[Normand Leblanc]

One of the problems with the test is that both the clearance angle and the bevel angle were varied simultaneously. It is difficult to separate which was the dominant factor.
How can it be otherwise? If the bevel angle is changed/varied then the clearance angle (relief angle) is also varied.

Here is a study.
http://planetuning.infillplane.com/html/review_of_cap_iron_study.html

One of the conclusion is:

"The force perpendicular to the direction of planing reverses with distance planed. Initially the blade is pulled into the wood surface, but as the blade gets dull, in particular that the flat spot develops on the back (beveled side) of the blade, the blade is pushed away from the surface. In hand planing these forces would initially pull the plane into the planed surface, but with dulling, the plane would be pushed away from the surface "

For me, the most important factor that determine when I need to resharpen is the pressure that I have to add on the front knob. In normal planing, once the blade is well engaged, I do not apply any pressure in the front. If you do, how do control the end of the cut...you will most likely round up the end of the board.

Pat,
Why don't you sharpen at 45 with the bevel parallel with your wood? The reason is that you would not be able to engage a cut because the large surface of your bevel would require an enormous amount of vertical force for the blade to engage a cut. This is one of the reasons we have a relief angle. The question that I'm trying to answer is "what is the best angle".

I've started those test because it was obvious to me (may have to do with my sharpening method) that I was getting more life from BD blades compared to BU. So far it seems that 25 degrees is the best angle for soft wood at least. Much better than 35 degree.

[Patrick Chase]

There is a difference between passing a piece of metal over an abrasive and passing a sharp edge over wood. For one, when working a bevel on metal against abrasive there isn't a need for a relief angle. Another is the abrasive sheet is more likely to 'bubble' in front of the metal. In the video by Professors Kato and Kawai it is possible to see the wood being planed actually rebounding behind the cutting edge. I'm not an expert in physics, but it is my guess that this wood rebounding is part of the reason a blade needs to have a relief angle. With a relief angle of 20º there is a lot more room for wear to the bevel and relief angle than with there is with a relief angle of 10º.

We're talking about two different things here.

Yes, wood compresses and rebounds, and you need relief to deal with that . That was actually my entire point in starting this thread (seriously, look at #1). I also specifically acknowledged that again when I replied to you in #39 (http://www.sawmillcreek.org/showthread.php?244074-Clearance-in-BD-plane&p=2567740#post2567740). I'm not sure why this keeps coming up as though it were a topic of debate or relevant to my points about wear. It is neither.

Now with that out of the way, can you please look at the micrographs Kees posted? They show pretty clearly that the wear patch is flat (zero clearance).

[Pat Barry]

Pat,Why don't you sharpen at 45 with the bevel parallel with your wood? The reason is that you would not be able to engage a cut because the large surface of your bevel would require an enormous amount of vertical force for the blade to engage a cut. This is one of the reasons we have a relief angle. The question that I'm trying to answer is "what is the best angle"..
Oh yes, I see all that and agree that the more acute angle will cut better, at least to start. All I'm saying is that it was surprising that your results showed that the more acute angle held up longer by producing 2 mil shavings significantly longer than the more traditional bevel angle.

[Normand Leblanc]

I was also surprised. I was thinking that 30 maybe more would be the best angle. Anyway, I've redone all that test and, even if there are some differences, 25 degrees is still the best angle by far...in soft wood... with a Record blade. Just wait a few more days and I'll have a decent study to show with plenty of data to discuss.

Right now I've began testing a Stanley blade and it doesn't look good at all so far. Much worse than a Record blade. In fact it's not even a surprise for me.

http://oldchips.blogspot.ca/2016/05/study-edge-retention-of-plane-iron-with.html

[bridger berdel]

George-
This group is self-selected for liking to chatter on the internet. What the actual topic is may be not so important...





For heaven's sake. You guys can dwell on nothing of importance forever. The real point is: can you USE your tools to make beautiful things. Do you know design? Can you draw(knowing design does not mean you can draw). Can you do accurate work? And several others.

[Stewie Simpson]

Excellent work Normand. Question for you regarding the results you posted within your link; can you explain how you ended up with an included angle of 48* when the bevel angle is only 35*.

https://www.youtube.com/watch?v=UFMy2knKAwI

regards Stewie;

[Jim Koepke]

All I'm saying is that it was surprising that your results showed that the more acute angle held up longer by producing 2 mil shavings significantly longer than the more traditional bevel angle.

Isn't the traditional angle for Stanley blades 25º?

Maybe these tests were done way back in the beginning of plane use.

jtk

[Stewie Simpson]

Normand; re the results you posted. If dykem were to be applied to the bevel of the plane iron before each of the following 5 tests; would that have highlighted any changes within the wear pattern as the relief angle was progressively reduced.

The results for a 0.002" shaving are:



sharp. Angle
Relief angle
# shavings


Test 1
25
20
120


Test 2
28
17
95


Test 3
31
14
90


Test 4
34
11
70


Test 5
37
8
35

[Normand Leblanc]

Haha!
The geometry is quite simple. All those irons have been sharpened with a 3 degree backbevel. I think that by doing this I rapidly remove the wear bevel.

As for "dykem", english being a second language for me, I presume that it means like coloring/painting. If it's the case, I doubt that it would show anything but, having more test to do I'll give it a try and let you know.

Good night

[Stewie Simpson]

Isn't the traditional angle for Stanley blades 25º?

Maybe these tests were done way back in the beginning of plane use.

jtk

Jim. Its funny you should mention that; yesterday during a cleanout of the workshop I came across an old instruction manual that's supplied with a Stanley Bench Plane purchase, and it states; The cutter is supplied at a ground angle of 25*. Before use the cutter must be honed at 30*

Stewie;

[Steve Voigt]

I was also surprised. I was thinking that 30 maybe more would be the best angle.


Well, that is one mark of a good test, when the results surprise you or seem a little counterintuitive; it suggests that you didn't let your own bias control the test. But you repeated the test and got (basically) the same results, which suggests to me that the test is valid and useful.

I see some people complaining that the test is not "real world" enough. The truth is that there never has been, and probably never will be, a test that exactly duplicates real working experiences. You always give up a little reality, in order to simplify and quantify. But that doesn't mean that the test isn't useful. I think what's really going on is that these people feel threatened by data that contradicts their entrenched outlook. Oh well, too bad for them.

My one caveat is that you are taking thin shavings in softwood; I wonder if the results would be the same with harder woods and/or thicker shavings. I suspect not, but I don't really know.

Anyway, I'm looking forward to seeing the rest of your data.

[Jim Koepke]

We're talking about two different things here.

Yes, wood compresses and rebounds, and you need relief to deal with that . That was actually my entire point in starting this thread (seriously, look at #1). I also specifically acknowledged that again when I replied to you in #39 (http://www.sawmillcreek.org/showthread.php?244074-Clearance-in-BD-plane&p=2567740#post2567740). I'm not sure why this keeps coming up as though it were a topic of debate or relevant to my points about wear. It is neither.

Now with that out of the way, can you please look at the micrographs Kees posted? They show pretty clearly that the wear patch is flat (zero clearance).

Yes, you brought up rubbing metal on an abrasive and my comment is it is totally different than a blade on wood.

From your post #1:


The reason I'm posting this is because I'm firmly of the opinion that extra clearance is nothing more than wasted blade life, so it pays to know where the real limits are. I think it's good to have some margin, so I'm going to continue to aim for ~10 deg clearance.

Note: All of my bevel down bench planes have a 45º bedding. All of my relief angles discussed are in relation to this bed angle.

It seems Normand has test results which indicate the 10º clearance angle will have diminishing effectiveness sooner than a 20º clearance angle. Are you saying you may have to hone the blade more often but each time is removing less metal than those of us with bevels starting with more clearance?

I'm not sure what point you are trying to make, but it has not sold me on changing my bevel angles for bevel down planes.

From your post #39 in this thread:



If you look at Kees' diagrams (and many others out there) what you actually see is a ~flat wear patch developing behind the edge. It's more "an ever-growing patch of zero clearance" than "reduced clearance". That's why I'm not entirely sold on the link between the initial clearance angle and problems with wear bevel. That flat spot is going to form no matter what angle you start at, so the real question is "does it form faster with lower initial clearance".


I believe the answer is yes, with a lower clearance angle the wear formation affects the cutting action with less work output.

From the "Review of Cap Iron Study:"


The back, or beveled, surface shows a wear profile with a flat surface developed behind the tip at an angle of about 10 degrees, corresponding to the relief angle for the blade in this experiment. This wear is the result of the wood surface rubbing against the beveled side of the blade. It should be noted that this wear negates the relief angle of the blade. It will be shown that this wear surface pushes the blade away from the wood surface.

I have had my Veritas MkII Power Sharpening System for over 10 years. The instruction book that came with it had some discussion on bevel angles. My recollection is the comments on a 35º bevel angle was prone to skipping out of the work. I do not know where the manual is currently. Most likely it is packed away somewhere. If it is found in the near future I will post the exact wording.

In summary, my opinion is a 10º relief/clearance angle is not going to save any appreciable amount of blade metal. You will have to come up with something more convincing to get me to believe, "that extra clearance is nothing more than wasted blade life."

jtk

[Stewie Simpson]

Haha!
The geometry is quite simple. All those irons have been sharpened with a 3 degree backbevel. I think that by doing this I rapidly remove the wear bevel.

As for "dykem", english being a second language for me, I presume that it means like coloring/painting. If it's the case, I doubt that it would show anything but, having more test to do I'll give it a try and let you know.

Good night

Thanks for the update Normand. Makes perfect sense now. Excellent work.

Stewie;

[Patrick Chase]

It seems Normand has test results which indicate the 10º clearance angle will have diminishing effectiveness sooner than a 20º clearance angle. Are you saying you may have to hone the blade more often but each time is removing less metal than those of us with bevels starting with more clearance?

There is effectlively a "race" between two failure modes: Ordinary edge failure modfes like dulling and chipping, and loss of clearance due to wear behind the edge. I think that in with all else (bedding/cutting angle etc) equal it's fair to say that clearance represents a tradeoff between these modes.

As I've said a couple times I think that high clearance probably slows the formation of the flat wear spot a bit, so in that sense it mitigates loss of clearance a bit. Conversely, high clearance means a thinner edge and therefore higher vulnerability to more conventional failure modes.

I think that Normand's later work after he switched to rigid sharpening media is a terrific contribution too this discussion (and am ashamed not to have said so yet - my hat is off, Normand). He shows that in the specific case he tested (zero-vertical-force, cut-by-pull) relief significantly impacts useful life. The next question is of course: How does that translate to real human use, where the woodworker can generally sense the behavior of the blade and adjust accordingly, for example by applying a big of vertical force to start the cut. That was really Warren's point a few posts back.

So to recap we have the following:

1. Everybody agrees that you need some amount of overall clearance to deal with compression/expansion of the wood
2. We have micrograph evidence showing that wear causes formation of a "land" of zero clearance behind the edge rather than simple reduction of clearance
3. Normand shows that In the absence of vertical pressure the initial clearance angle has a significant impact on how long the plane cuts
4. Real users who do apply pressure (me, Warren, Derek) report MUCH longer blade lives than Normand's data suggest at fairly low clearance angles (~10 deg). I personally find that my blades become dull long before clearance becomes an issue

Taking all 4 together my guess is that the vertical pressure that we apply when using our planes "holds" the wood under the flat wear patch in compression until it reaches the relief bevel behind the wear patch. That allows real users (as in 4) to experience good performance with much worse wear than is tolerable for Normand's setup in (2). That in turn shifts the balance in favor of low relief. Just my $0.02 fwiw.

[Stewie Simpson]

Patrick; correct me if I am wrong. Normand's tests indicate that an included angle of 28* (25* primary + 3* secondary) is the ideal target to aim for with regards longevity of the cutting edge; your suggesting 30* is the ideal target. Their is only a minor discrepancy of 2* between both opposing views. As to the issue of wear angles; it should be remembered that you are starting with a bed angle of 40* ; whereas Normand is working with 45*. Clearly your commencing wear angle is going to remain 5* less than Normand's recommendation. From a personal judgement; given the choice between your starting point of a 10* wear angle, and Normand's 17*, I would opt for the latter as it offers me greater scope between periodical regrinding. As to the question on what I would deem as a minimal wear angle to work with; it would be close to 10 degrees. As someone who freehand sharpens, its difficult to give an exact no.

Stewie;

[Pat Barry]

I think what's really going on is that these people feel threatened by data that contradicts their entrenched outlook. Oh well, too bad for them. I don't see anyone being threatened by this in the least. Only speaking for myself though, the question in my mind is WHY the results are as presented. I'd like to understand this better personally because the key to improvement is understanding the root cause of the issue. Normand has presented som fascinating results that seem to buck traditional understanding and I'd like to understand why.

My one caveat is that you are taking thin shavings in softwood; I wonder if the results would be the same with harder woods and/or thicker shavings. I suspect not, but I don't really know. What angles do you use in your own wooden bodied planes Steve? Have you ever experimented with different angles? Would you make the angle of your own planes different if a customer was telling you up front that they were concerned with planing hardwoods?

[Warren Mickley]

Haha!
The geometry is quite simple. All those irons have been sharpened with a 3 degree backbevel. I think that by doing this I rapidly remove the wear bevel.


Am I reading this right? The angles presented to the wood in the experiment are really 28, 31, 34, 37, and 40? The 3 degree back bevel makes these tests equivalent to one with a 48 degree bed. I can't think that a 40 degree angle would not have trouble starting a cut without any pressure other than the weight of the plane. Dulling or not.

Consider these two situations: 1) a plane bedded at 48 with a 37 degree bevel. 2) a planed bedded at 41 with a 30 degree bevel. Both of these would have an 11 degree clearance angle, but I would expect these to give rather different results especially with the way your test is designed having initial penetration as the great factor.

It has been more than 40 years since I have used any angle other than 30 degrees or a backbevel. All but one of your tests exceed 30 degrees. I have used a plane with a 45 degree bed and a 30 degree bevel along side a plane with a 42 degree bed and 30 degree bevel since 1982. It is barely noticeable that the 42 bedding yields a better surface. I would question the suggestion that the iron bedded at 45 had longer edge life. I think your tests are measuring the bluntness of your angle (40 degrees!) as much as clearance.

[Jim Koepke]

Patrick; correct me if I am wrong. Normand's tests indicate that an included angle of 28* (25* primary + 3* secondary) is the ideal target to aim for with regards longevity of the cutting edge; your suggesting 30* is the ideal target. Their is only a minor discrepancy of 2* between both opposing views. As to the issue of wear angles; it should be remembered that you are starting with a bed angle of 40* ; whereas Normand is working with 45*. Clearly your commencing wear angle is going to remain 5* less than Normand's recommendation. From a personal judgement; given the choice between your starting point of a 10* wear angle, and Normand's 17*, I would opt for the latter as it offers me greater scope between periodical regrinding. As to the question on what I would deem as a minimal wear angle to work with; it would be close to 10 degrees. As someone who freehand sharpens, its difficult to give an exact no.

Stewie;

Okay, you noticed the difference in the bed angle. My understanding is Normand didn't use a secondary bevel. He used a 3º back bevel.

The lowest angle I know of for a clearance angle is 8º on Stanley and Lie Nielsen side rabbet planes.

jtk

[Normand Leblanc]

Am I reading this right? The angles presented to the wood in the experiment are really 28, 31, 34, 37, and 40? The 3 degree back bevel makes these tests equivalent to one with a 48 degree bed. I can't think that a 40 degree angle would not have trouble starting a cut without any pressure other than the weight of the plane. Dulling or not.

Consider these two situations: 1) a plane bedded at 48 with a 37 degree bevel. 2) a planed bedded at 41 with a 30 degree bevel. Both of these would have an 11 degree clearance angle, but I would expect these to give rather different results especially with the way your test is designed having initial penetration as the great factor.

It has been more than 40 years since I have used any angle other than 30 degrees or a backbevel. All but one of your tests exceed 30 degrees. I have used a plane with a 45 degree bed and a 30 degree bevel along side a plane with a 42 degree bed and 30 degree bevel since 1982. It is barely noticeable that the 42 bedding yields a better surface. I would question the suggestion that the iron bedded at 45 had longer edge life. I think your tests are measuring the bluntness of your angle (40 degrees!) as much as clearance.

Warren,
As I can see this 3 degree backbevel wasn't clear. In my french blog, where all this started, the readers are very well aware that this is my standard sharpening technique. I've updated the blogs to clarify this. I have a video showing my technique (in french but no need to understand, just look)
https://www.youtube.com/watch?v=5XLBm0SAZyY&feature=youtu.be

So you're right, it's like if those tests were done with a 48 degree bedded plane. If this makes a large difference (compared to 45) then all those people using 50 and 55 degree should see a much large blunting effect. My opinion (nothing scientific here) is that the difference is minimal between 45 and 48.

As I said before, I've decided to do some testing after getting a new LN 4-1/2 that was giving me so many more shaving than the 3 BU planes that I own, sharpened at 30-35 degree. With the bed angle of 12, this gives 42 to 48 degree which is close to a standard BD. What was going wrong? That's why I came to the conclusion that it had to do with the relief angle and I began testing this right away. I'm far from being completed with those test but, using softwood, a Record blade and 48 degree frog, a 25 degree (+3 = 28) sharpening angle is much better than all the other steeper angles.

If I was to use a 41 degree bedded plane, I believe that I would be getting more shavings than a 45 degree plane if both had the same relief angle. This is just an opinion, I haven't tested that. That would be a very nice test to do and, if I'm right, would give LV an edge to LN. Derek Cohen seems to be getting very good results with a lower bed.

That being said, I've been hand sharpening my blades for 5 years with an angle of 30-35. If the test with hardwood gives the same kind of results I'll have to change my method or live with a poorer result.

Have a good day

[Normand Leblanc]

Thank you Patrick for your contribution convincing me that I should not strop.

"There is effectlively a "race" between two failure modes: Ordinary edge failure modfes like dulling and chipping, and loss of clearance due to wear behind the edge. I think that in with all else (bedding/cutting angle etc) equal it's fair to say that clearance represents a tradeoff between these modes.

As I've said a couple times I think that high clearance probably slows the formation of the flat wear spot a bit, so in that sense it mitigates loss of clearance a bit. Conversely, high clearance means a thinner edge and therefore higher vulnerability to more conventional failure modes. "

I agree entirely with the above.

Where I disagree now. I believe that edge failure is less important than the formation of a flat. At this stage I've tested softwood. When I'll do hardwood we will have more information to answer this question.

The technique I'm using is, a given mass (the plane) applied to an area (flat under the blade) and a dull blade, taken together, is able or not to take a shaving. If you add vertical force (like point 4) you will be able to use it for a longer period but IMO it will be close to proportional to the test results.

Hum...What do you think?

[bridger berdel]

unfortunately the three angles- cutting angle (set by the frog), clearance angle and bevel angle are inseparably linked. even if you built a variable angle frog to do the tests with you would not be able to isolate 1 angle as a variable.

and yes, measuring the grab with just the weight of the plane isn't relevant to actual use.




One of the problems with the test is that both the clearance angle and the bevel angle were varied simultaneously. It is difficult to separate which was the dominant factor. And in addition the test was done without the normal downward pressure; it tested only the irons ability to grab hold of the board and take a shaving. I think this would tend to bias the results toward a more acute honing angle, regardless of the clearance angle.

[Kees Heiden]

unfortunately the three angles- cutting angle (set by the frog), clearance angle and bevel angle are inseparably linked. even if you built a variable angle frog to do the tests with you would not be able to isolate 1 angle as a variable.

and yes, measuring the grab with just the weight of the plane isn't relevant to actual use.

Indeed not relevant to the actual use, but it is not ment as such. It is used as an indication for the size of the wear bevel. We could quible of course if it is a good indicator.

BTW, I read somewhere in this thread that the wear bevel at the clearance side would be flat. But it isn't. The wearbevel is a bulge. The edge is raised higher and higher above the lowest point of this bulge. This is a gradual proces. When researchers measure the vertical force, this is very clear, the vertical force changes gradually too with distance planed. This is universally recognised to be a good wear indicator in the wood cutting science area.

[Normand Leblanc]

The flat/bulge seems to vary depending on grain direction. From Kato and Kawaii:

http://planetuning.infillplane.com/html/review_of_cap_iron_study.html

I'm planing with the grain with an grain angle anywhere between 0 and +7. I can see that the shaving thickness is getting smaller but it's hardly measurable with a regular micrometer.

[Pat Barry]

Indeed not relevant to the actual use, but it is not ment as such. It is used as an indication for the size of the wear bevel. We could quible of course if it is a good indicator.

BTW, I read somewhere in this thread that the wear bevel at the clearance side would be flat. But it isn't. The wearbevel is a bulge. The edge is raised higher and higher above the lowest point of this bulge. This is a gradual proces. When researchers measure the vertical force, this is very clear, the vertical force changes gradually too with distance planed. This is universally recognised to be a good wear indicator in the wood cutting science area.
Kees, I really think the pictures on your webpage (http://bladetest.infillplane.com/html/wear_profiles.html)are now so much more relevant to me (after all of the above discussion). As was mentioned previously, as the edge becomes eroded after planing lumber, the downforce required to overcome the wear effects becomes more significant. Looking back at your pictures this alll makes perfect sense. I see now that Normans work does a great job of tabulating that effect. For me personally, one that doesn't enjoy the sharpening process all that much, I can see the merits of using the more acute bevel angles. I wonder now if perhaps going to an angle even less than 25 degrees might not be a bad idea. Thoughts?

[Kees Heiden]

Just to be sure, those are not my pictures! I only pointed out where they are. It's the work from Steve Elliot, who was also so kind to give room on his website for my articles about chipbreakers.

[Warren Mickley]

I tried Normand's experiment this morning with two of my planes:

Plane 1) #3 Bailey c1915, 47 ounces, 45 degree bed, 15 degree clearance
Plane 2) #4 Stanley Handyman 1973, 50 ounces, bed altered to 42 degrees, 12 degree clearance

Both planes had century old Stanley irons, sharpened full flat bevel on Arkansas stones and stropped on clean leather. I used a 30 degree angle bevel; no back bevel.

Both planes passed the test even after 200 strokes on white pine (Pinus strobus). In both cases I felt the urge to sharpen the irons somewhere in the 120-150 range, but kept going for the sake of the experiment. I don't like to abuse an iron by running it into the ground.

Four of Normand's tests were done with higher sharpening angles (bevel plus back bevel) than mine, which I think is a significant factor. And all of Normand's tests were done with higher cutting angles (bed angle pus back bevel) than mine, which I think also plays a role.

I don't recommend micro bevels, secondary bevels, tertiary bevels, back bevels or ruler tricks. And I don't recommend planing above 45 degrees.

[Normand Leblanc]

Warren,
If you're right about the high angles that means our BU planes do have a problem when sharpened at 50, 55 and 60 degrees.

The test that I'm doing are called completed when the plane with his own weight, pushed by the rear part of the sole, do not engage a full cut. How did you called your test completed? Same as me or another method?

The Stanley blade that I'm using is just stamped Stanley. I believe it's a newer one than yours.

[Warren Mickley]

I started the test pulling the plane with a string on the knob, but then I reread your post and ended by pushing the plane at the base of the rear. I did not really complete the tests; both planes were still cutting with their own weight at 200 strokes, but I got tired of it. I don't care to go beyond where my instincts suggest sharpening.

[Normand Leblanc]

Our results are quite different... The differences between you and me could be:

- blade type (I know that I can get a lot more shaving with a better blade. Maybe your old stanley blade is much better than mine)
- I'm planing a 26" long timber. What's your length?
- Timber 1" wide. What's your width?
- Pine (if it's white pine) is 380 Janka, Fir is 660.
- Stropping.
- The plane itself. Yours are smaller than my no.5... I should be getting more shavings here!
- The higher angle (48 degree approx) that I'm using.

From earlier post I got that you're using planes for a very long time. With your experience, if you had to figure out why we are getting very different results, which one of the items listed (or maybe something else) would you suggest to look at?

[Jim Koepke]

I can see the merits of using the more acute bevel angles. I wonder now if perhaps going to an angle even less than 25 degrees might not be a bad idea. Thoughts?

One of the points I recall from the booklet that came with my sharpening system is angles at 25º or less tend to be more prone to chatter.

It may be worth giving it a try and then reporting back.

I do know my chisels with bevels of less then 25º are great for paring but are more prone to wear at the edge.

jtk

[Patrick Chase]

Our results are quite different... The differences between you and me could be:

- blade type (I know that I can get a lot more shaving with a better blade. Maybe your old stanley blade is much better than mine)
- I'm planing a 26" long timber. What's your length?
- Timber 1" wide. What's your width?
- Pine (if it's white pine) is 380 Janka, Fir is 660.
- Stropping.
- The plane itself. Yours are smaller than my no.5... I should be getting more shavings here!
- The higher angle (48 degree approx) that I'm using.

From earlier post I got that you're using planes for a very long time. With your experience, if you had to figure out why we are getting very different results, which one of the items listed (or maybe something else) would you suggest to look at?

Warren is probably putting a better edge on his blades than any of us, and that would go a long way to explain the difference.

Wood compressibility (~Janka) is another strong candidate IMO, as is abrasiveness.

[david charlesworth]

Did anyone come up with an answer to optimal clearance angle??

David

[Kees Heiden]

And the grain of the wood. It is the shaving that pulls the edge down. So the strength, the elasticity, the shaving thickness and the grain direction all play a large role. You can only compare results in a scientific way when you keep things constant.

[Jim Koepke]

Did anyone come up with an answer to optimal clearance angle??

David

Yes, though the one that seems to work best for me may not be the one that works best for you.

jtk

[Normand Leblanc]

This thread was a good resource for me. It helped me to refine my procedure quite a bit.

At this stage, all I can say is, a clearance angle of 14-20 degrees has given more shavings than 8-11 degrees by a significant margin. This is true for every single test performed to date. 14 degrees seems to be the lowest clearance without major loss of edge life but 20 is as good or better.

This is with BC Fir and Cherry and with blades from Stanley and Record.

Other species (harder) will be tested as well as modern steel blades (O-1, A-2, PM-V11, Hock). All results will be for everyone to see and discuss/argue. It's quite a bit of work, more than I was thinking, so it will require a couple of weeks.

[Patrick Chase]

This thread was a good resource for me. It helped me to refine my procedure quite a bit.

At this stage, all I can say is, a clearance angle of 14-20 degrees has given more shavings than 8-11 degrees by a significant margin. This is true for every single test performed to date. 14 degrees seems to be the lowest clearance without major loss of edge life but 20 is as good or better.

This is with BC Fir and Cherry and with blades from Stanley and Record.

Other species (harder) will be tested as well as modern steel blades (O-1, A-2, PM-V11, Hock). All results will be for everyone to see and discuss/argue. It's quite a bit of work, more than I was thinking, so it will require a couple of weeks.

One question I keep coming back to is: What's the value of not having to apply downward pressure?

Put another way, if a plane won't self-initiate at some clearance angle but works with very modest pressure, is that a bad thing? Should we even care? Those totes are angled for a reason, after all.

[Normand Leblanc]

I'm making an assumption!

When a test is completed it gives a picture of the cutting edge. At that particular moment the edge is shaped with a given wear "flat" on the bevel and a given rounding at the tip. The assumption is to pretend that all tests are giving a similar picture (same edge wear). I know that it's not perfectly true but it should not be far from the reality. One thing is sure...the vertical force required that keeps the blade from cutting is very close test after test and that imply a similar "flat".

A completed test doesn't mean that the blade needs to be resharpen. It only means that the edge has been worn-out as much as the previous test (or all the other tests). You can add whatever downward pressure you wish, each one of us have its own technique, but it has been demonstrated that the force required grow linearly with the number of shavings if I remember correctly.

Taking this into account, the idea is to reduce the rate of growth of that "flat" while keeping a strong edge. I think that we have agree on that earlier. What I'm saying right now (all tests are far from completed) is the flat seems to be growing faster with a 10 degree clearance angle compared to 20 degree. The 10 degree blade will feel dull before the 20 degree one.

Have a good day

[Stewie Simpson]

4. Real users who do apply pressure (me, Warren, Derek) report MUCH longer blade lives than Normand's data suggest at fairly low clearance angles (~10 deg).

Normand; ignore comments such as that made above; it adds little to no value to the discussion; you have my support and no doubt many others who look forward to following your progress with great interest.

regards Stewie;

[Patrick Chase]

And the grain of the wood. It is the shaving that pulls the edge down. So the strength, the elasticity, the shaving thickness and the grain direction all play a large role. You can only compare results in a scientific way when you keep things constant.

Yeah, grain direction is a huge variable here. Planes start cutting very easily indeed right before they tear the living sh*t out of your workpiece (yes, I know about cap irons. Yes, that was an exaggeration for dramatic effect :-).

[Jim Koepke]

+1 on the above

While using my #6 today I notice that there may be some downward pressure. However the majority of effort is toward the direction of travel.

jtk

[Pat Barry]

I suspect now that old steel was probably softer. New steels are much tougher and therefore can keep an edge longer. I can't wait for the tests on PMV11.

[Normand Leblanc]

You don't even have to wait, comparing old steel with newer ones like A-2 or PM-V11 is something that I have done already. The link is somewhere in this thread but in case you missed it.

http://oldchips.blogspot.ca/2016/05/study-edge-retention-of-plane-iron-with.html