Reason for secondary bevel ?

[lou Brava]

I've only used bench chisels always sharpened using Japanese stones completely honing the entire face, as you can imagine this process takes a lot of time & effort especially if there's a nick. I just ordered a set of mortise chisels (Narex) and reading about secondary bevels being the way to go. From what I gather the big advantage to a secondary bevel is you only have to sharpen a small part of the face which makes sense, the other is the edge will stay sharp longer but that part really doesn't make sense to me. Is there some science behind that or is it just expert wood workers and experience that claim this ? Either way I'm going to try the secondary bevel just for ease of sharping.
Thanks

[Tony Wilkins]

It’s just one option among many. The ‘science’ is that you’re only honing the small amount of steel at the tip. Of course you can continue to do he whole face but know that whereas the oire nomi has the soft steel on top the other will be all harder steel. Some use hollow grinding to provide a quicker hone. I learned from Charlesworth and the Schwarz so I use a micro bevel.

[Kendall Scheier]

The reason that the edge lasts slightly longer is that the angle of the steel is more obtuse providing more support to the cutting edge making it less likely to chip or fracture…. It’s a small incremental difference but we all live that kind of stuff lol

[Eric Brown]

I've only used bench chisels always sharpened using Japanese stones completely honing the entire face, as you can imagine this process takes a lot of time & effort especially if there's a nick. I just ordered a set of mortise chisels (Narex) and reading about secondary bevels being the way to go. From what I gather the big advantage to a secondary bevel is you only have to sharpen a small part of the face which makes sense, the other is the edge will stay sharp longer but that part really doesn't make sense to me. Is there some science behind that or is it just expert wood workers and experience that claim this ? Either way I'm going to try the secondary bevel just for ease of sharping.
Thanks

The shorter bevel is stiffer, meaning that it is stronger. Downside is that it is also harder to use. (The higher the angle the more force required to use). These very slight differences are not noticeable to most of us. When looking at bevel angles there are two things to consider. One is clearance. We all like to think that when the edge cuts the surface doesn't change, but there is some compression that happens. That is why you don't use a 45 degree bevel on most hand planes. The other thing to consider is that it can be compared to a screw thread. The finer the thread the easier to turn but the slower it progresses. Skewing a plane has the same effect as a lower angle. Yes it's easier but the cut width is reduced. All the angles are compromises. The ideal angle will probably be different depending on the blade thickness (thicker doesn't vibrate as easy), the type of wood. Even how the chip breaker is set. Over the years the 45 degree angle of most planes is an angle that will work for most woods. When working with difficult grain, or super hard woods, different approaches might need to be utilized. Another downside of a secondary bevel is that eventually you will be required to grind the primary bevel back to where the secondary is easier to maintain. So when looking at the time it takes it really depends on your sharpening routine. Do you sharpen after every use? To you just want to do a quick sharpen to get some work done?

Personally I do both except I don't sharpen after every use but once a month I check all the blades and spend the time to sharpen what needs it. If I'm working and the blade seems dull I sharpen the secondary.

There are also those that don't grind flat but put a hollow grind on. This makes the number of secondary sharpenings greater.

Confused? Lost Art Press has a book on sharpening I would recommend.

[steven c newman]

There are some out there that even put FOUR bevels on an iron.....

Then, there are some like me that only use a single bevel...

All depends...as to where one wants to spend their shoptime at......at the sharpening "bench", or...simply put the plane to work...

[Edward Weber]

The reason that the edge lasts slightly longer is that the angle of the steel is more obtuse providing more support to the cutting edge making it less likely to chip or fracture…. It’s a small incremental difference but we all live that kind of stuff lol
+1
My understanding is that the secondary bevel was developed for use with plane irons, which are thinner than chisels and have little support behind the cutting edge.

[mike calabrese]

Here is some info on the secondary bevel applied to plane blades and chisels
calabrese55


https://www.youtube.com/watch?v=t-Vwlbi0hcQ
https://www.youtube.com/watch?v=m7xNQ-XEoNI
https://www.youtube.com/watch?v=Q4f4d3VRqY4
https://www.youtube.com/watch?v=m7xNQ-XEoNI
https://www.youtube.com/watch?v=N6qa9kkfA2Y

[steven c newman]

Delaware County, NY? have relatives buried up there...Abner Newman's Father is Buried there. Abner Newman bought "Government Land" down here in Ohio...1792...and moved to the Logan County area...One of the first Methodist Churches was set up on his land..1822...

Just getting old and set in me ways...

[Tom M King]

My reason for almost never using a secondary bevel is that you almost never have to use a grinder. None of my plane irons have visited a grinder in more than a few years, and only the chisels that have damage from some use other than cutting wood. Still only a few minutes from scraping paint off of brick to more than razor sharp. Much less for an undamaged edge.

[Jim Koepke]

My tendency is to maintain a flat bevel on my chisels.

Using a chisel bevel down is a bit tricky with a secondary bevel.

A secondary bevel may have less area to work, but it is difficult to hold such a small area flat on a stone when freehand sharpening. Eventually the small area gets bigger and needs to be reground. Like Tom, my blades seldom get near a grinder.

My mortise chisels may have a different setup than my plane blades, chisels and gouges.

There are also different sets of chisels in my shop. One set is ground at a very low angle for paring. Another set is ground to a steeper angle for rougher work or being struck by a mallet.

jtk

[Rafael Herrera]

Japanese chisel have a very thin layer of steel forge welded to a wrought iron backing (i.e. soft), so sharpening them maintaining a single bevel is practical. Most modern western chisels are all hardened steel, so using the single bevel approach would take a very long time and not be practical.

One of the many methods of sharpening bench chisels or plane irons (mind you, not mortise chisels) is to grind a shallower main bevel, around 25 degrees or less, by some means, not something done every time. When honing the edge, one lifts the chisel a bit above 25 degrees and works the edge. One does this until the secondary bevel is too big or takes too long to work, that's when the main bevel is reground.

On mortise chisels, which are subject to prying, the apex at the edge needs to be an angle more obtuse than what you would use on bench chisels. That prevents the edge from chipping when you pry. One uses a mallet with the mortise chisel, so they need to be sharp, but not at the level of bench chisels.

Prying will damage an edge, so you have to adjust your sharpening according to what you will do w the chisel. If you're going to pare, you can go pretty shallow. If you're going to chop, you can't go as shallow. Your baseline is around 25 degrees, start there.

[Jimmy Harris]

For me, secondary bevels make sharpening harder, not easier. For one, you don't have the big flat surface to reference against. And a sharpening jig adds unnecessary time, cost, and complication. And two, if you only ever sharpen the secondary bevel, eventually you'll find yourself in a situation where you have to regrind the primary bevel once you worked that secondary bevel far enough back. And then you've got a ton of work on your plate, because you're having to remove A LOT of material. So to avoid that, I sharpen both the primary and secondary bevels on my mortise chisels every time I sharpen them. It doubles my sharpening time, but it prevents me from having to grind the chisel down at some later date. And this is why I only use secondary bevels on mortise chisels, since they're the only tools that, in my opinion, take enough advantage of a secondary bevel to be worth the hassle.

But that's just my opinion. Other people have no problem taking their chisels over to a bench grinder and regrinding the primary bevels once in a long while. And there's no right or wrong way to go about it, so long as the way you choose works for you. It's all a tradeoff, and we each get to decide which qualities are most and least important to us. I get paid the same no matter which method you choose, so I have no incentive to convince you my way is right for you.

[Mark Gibney]

I might be confused but it looks to me like the OP asked about putting a secondary bevel on a chisel, not a plane iron, in place of flattening the entire face.

I just ordered a set of mortise chisels (Narex) and reading about secondary bevels being the way to go. From what I gather the big advantage to a secondary bevel is you only have to sharpen a small part of the face

I would never put a secondary bevel on the face of a chisel. Am I misinterpreting the question?

[mike stenson]

I might be confused but it looks to me like the OP asked about putting a secondary bevel on a chisel, not a plane iron, in place of flattening the entire face.

I just ordered a set of mortise chisels (Narex) and reading about secondary bevels being the way to go. From what I gather the big advantage to a secondary bevel is you only have to sharpen a small part of the face

I would never put a secondary bevel on the face of a chisel. Am I misinterpreting the question?


On the face? I absolutely do, especially on say a2 steel. It's no different than a hollow grind. On the back? No.

[Rafael Herrera]

I might be confused but it looks to me like the OP asked about putting a secondary bevel on a chisel, not a plane iron, in place of flattening the entire face.

I just ordered a set of mortise chisels (Narex) and reading about secondary bevels being the way to go. From what I gather the big advantage to a secondary bevel is you only have to sharpen a small part of the face

I would never put a secondary bevel on the face of a chisel. Am I misinterpreting the question?

The references to plane irons were included because they can be sharpened in a similar manner. I always think of the "face" of a chisel or plane iron as the flat side of the tool, so the bevel side is the "back". Some people refer to them in the opposite way, the OP may be one of them, who knows. It helps top think that the face is what makes contact with the wood.

[mike stenson]

The references to plane irons were included because they can be sharpened in a similar manner. I always think of the "face" of a chisel or plane iron as the flat side of the tool, so the bevel side is the "back". Some people refer to them in the opposite way, the OP may be one of them, who knows. It helps top think that the face is what makes contact with the wood.

See, I am certainly one who refers to the flat / reference side as the "back". As in "flattening the back of a chisel".

[Rafael Herrera]

See, I am certainly one who refers to the flat / reference side as the "back". As in "flattening the back of a chisel".

You certainly don't put one of those terrible ruler trick "back bevels", do you? That's one of the worst suggestions coming out of the Internet's gurudom.

[mike stenson]

You certainly don't put one of those terrible ruler trick "back bevels", do you? That's one of the worst suggestions coming out of the Internet's gurudom.

on a chisel? nope.

my great-uncle was effectively doing that on his plane irons in the 1930s btw.

[Alex Shanku]

That's one of the worst suggestions coming out of the Internet's gurudom.

With a ruler that's 1/16" thick, it's about 1* of bevel and about 1/8" long. Surely there must be many worse suggestions out there :D

Also, I've never heard anybody refer to the flat surface of a chisel or plane as the "face", is this carry over from another trade/industry?

[Jim Koepke]

I've only used bench chisels always sharpened using Japanese stones completely honing the entire face, as you can imagine this process takes a lot of time & effort especially if there's a nick. I just ordered a set of mortise chisels (Narex) and reading about secondary bevels being the way to go. From what I gather the big advantage to a secondary bevel is you only have to sharpen a small part of the face which makes sense, the other is the edge will stay sharp longer but that part really doesn't make sense to me. Is there some science behind that or is it just expert wood workers and experience that claim this ? Either way I'm going to try the secondary bevel just for ease of sharping.
Thanks

For my bench chisels, a honing the entire face is preferred. If care is taken to not hit nails or get into other incidents to damage the blade it doesn't seem to take much more time to keep my edges sharp.

For mortise chisels some like a secondary bevel and others prefer a convex bevel. A convex bevel can have a higher angle flat bevel at the business end if one so desires. A convex bevel also lends some help when levering out mortise waste.

jtk

[Edward Weber]

[QUOTE=Rafael Herrera;3285926]The references to plane irons were included because they can be sharpened in a similar manner. I always think of the "face" of a chisel or plane iron as the flat side of the tool, so the bevel side is the "back". Some people refer to them in the opposite way, the OP may be one of them, who knows. It helps top think that the face is what makes contact with the wood.[/QUOTE

Saying the face (flat side in your case) is what makes contact is just confusing to me, as a chisel is used in bevel up or down orientation depending on the task. For a bevel down plane, it sort of makes sense.
511243
Face and back have the same meaning, sure that's not confusing at all :rolleyes:

[Rafael Herrera]

The references to plane irons were included because they can be sharpened in a similar manner. I always think of the "face" of a chisel or plane iron as the flat side of the tool, so the bevel side is the "back". Some people refer to them in the opposite way, the OP may be one of them, who knows. It helps top think that the face is what makes contact with the wood.

Saying the face (flat side in your case) is what makes contact is just confusing to me, as a chisel is used in bevel up or down orientation depending on the task. For a bevel down plane, it sort of makes sense.
511243
Face and back have the same meaning, sure that's not confusing at all :rolleyes:



When thinking of bevel down plane irons, it make sense to me. The flat side of the cutter is what is "facing" the wood when it makes contact. The maker's stamp on plane irons is also on the flat side, one more reason to refer to that side as the face. However, the maker's stamp on chisels are on the bevel side, so that fails.

A chisel wedges itself into the wood, so the comparison with a plane iron is not as good.

For the chisel, I've also seen the flat side called "back face", so presumably there's a "front face". Call it whatever you want, just don't expect everybody understand what you're referring to, as I do.

[Reed Gray]

A very common tool used on the wood lathes is a NRS (negative rake scraper). It is used mostly for very fine clean up cuts. The first one used was a skew chisel, and the bevel angles are in the 30 degree range on each side. A common 'rule of thumb' is that combined angles should not be more than 90 degrees. I didn't like the skew chisel variety because the burr was so flimsy that you would only get a few seconds out of it. I ended up with a 60/30 bevel, with the 60 being on the bottom. Current theory is that you need a certain amount of mass under the burr to support it as a cutting edge. I also prefer a burnished burr as being far more long lasting, and cutting finer than the grinder burr. This seems to hold up. As for flat work tools, the burr is honed off, with the exception of the card scrapers. I am one who 'has' to experiment, just in my nature. I blame my dad. So, if the edge is really bad, I take it to a grinder with a CBN wheel. The hollow grind issues consist mostly of a 'slightly more acute angle' on the cutting edge. I don't know how acute it actually becomes, but the amount is minimal, almost unmeasurable, and I don't consider it a real issue. Maybe later I might change my mind as I get more experienced. The Japanese style tools all have flat bevels, and tend to be slightly more acute than western tools. So, I have a few Japanese style chisels and some Japanese style hand planes. I actually got one set up correctly and can take paper thin shavings with it, well thinner than paper.... I will keep on keeping on with the experiments. I would guess that the main point of the micro/secondary bevel is that you are only sharpening that small part of the whole blade. Does it actually make the tool function better? Not sure. I do know some prefer a more acute angle, like under 20 degrees for softer woods, which goes along with the idea of different plane angles for different woods. I doubt I will run out of things that need more experimenting.....

robo hippy

[steven c newman]

I simply refer to either the Bevel Face or the Flat Back face....

And the bevel face is just that...and I just use a single bevel on ALL of my cutting edges...plane iron or chisels. K.I.S.S.
Now, get back to work, before this becomes "Just Another Sharpening Thread"

[Robert Hazelwood]

The only thing that matters for edge durability and sharpness is the angle at the tip. Doesn't matter how many bevels or what shape they are. If the tool needs to make deep cuts then thinning out the bevel behind the edge will reduce resistance versus a single bevel. For shallow cuts like a plane blade it doesn't matter.

For most things I prefer to have a primary and secondary bevel. I maintain the primary with a belt grinder as a flat bevel at around 20 degrees, then hone freehand a small secondary at whatever angle I need. I don't like honing a large surface. The only tools I sharpen as a full flat bevel are Japanese, because they look cooler that way.

[Edward Weber]

The only thing that matters for edge durability and sharpness is the angle at the tip.

:confused:
The original point of the secondary bevel was to leave more material behind the cutting edge on plane irons, (bevel down) thus strengthening it, making it less likely to chip and increasing it's durability. It's less necessary with modern alloys.

This can be as simple or as complicated as people want to make it but there are valid reasons for and against secondary bevels on all cutting tools.

[Robert Hazelwood]

:confused:
The original point of the secondary bevel was to leave more material behind the cutting edge on plane irons, (bevel down) thus strengthening it, making it less likely to chip and increasing it's durability. It's less necessary with modern alloys.

This can be as simple or as complicated as people want to make it but there are valid reasons for and against secondary bevels on all cutting tools.

For a given final edge angle, any sort of primary grind is only reducing material behind the edge, which is the purpose. If two 1/8" thick blades have a final edge angle of 30 degrees, which has more material behind the cutting edge- one with a full flat 30 degree bevel or one with a small 30 degree secondary bevel and a primary grind of 25 degrees? The second will have less, and technically be weaker, but outside of extreme usage the relevant area for durability is the very tip and a few thousandths behind it. That's where any chipping or rolling will occur. So the edge angle at the tip is really all that matters.

If you are thinking of taking a full flat bevel of 30 degrees and then adding a 35 degree secondary bevel - then I agree that would increase material behind the edge in the area that matters, and so it will be more durable. But the main thing is just that you now have a 35 degree edge instead of 30.

[lou Brava]

FWIW, I posted about secondary bevels on chisels. I had read Paul Sellers blog and He seems to be in favor of em & I didn't understand the reason behind it. Now I understand the concept after reading all the post. For me I use Japanese water stones I don't own a grinder & I will not be putting a secondary bevel on my mortise chisels, much simpler to sharpen a single bevel & it doesn't appear to be any great advantage having the 2nd bevel. I received my Narex mortise chisels a few days ago & chopped some mortises today, big difference from my bench chisels I shouda bought these a long time ago !
Thanks everyone

[Jim Koepke]

I received my Narex mortise chisels a few days ago & chopped some mortises today, big difference from my bench chisels

Yep, big difference.

jtk

[Charles Edward]

Reason? A touch-up can happen in only a few strokes on a very narrow spit of steel. Otherwise, you don't have to have them.