Camber for plane blades, how much is enough/too much [Archive]

Mike Holbrook

10-22-2015, 1:21 PM

I spent a large part of my day yesterday sharpening and cambering plane blades for my family of Stanley planes. I use a mix of premium, wood, & restored planes. I typically use my restored planes more for rougher work reserving the premium planes for fine work. One reason for this strategy is my three Lee Valley BU planes have blades that can be a challenge to camber. I am aware that this can be done, and have read Derek Cohen's methods for doing this on his Blog. Still it makes more sense to me to set the premium planes up with smaller cambers for finer work. Obviously the thinner, often softer metal in older planes can be easier to grind camber into.

I probably should add that I have a grinder and CNC wheels. I realize that some may find these devises unnecessary but I am a tremendous fan. The speed and precision with which I was making cambered edges yesterday is something I have struggled with for years. Just being able to get immediate feed back, due to the faster cutting wheels, has dramatically improved my ability to make better/sharper tool edges.

I spent a while on Derek's site yesterday rereading various articles he has written on sharpening, especially since he started using CNC wheels. Like Derek I am largely a hand sharpener who likes to get done with the sharpening and back to cutting the wood. I was interested to read how Derek had evolved in his thinking about how much camber to put in a blade. From what I read I believe Derek himself is still working out precise cambers for specific planes and the blades they use.

The question that seems to rise is matching the camber to the width of a particular blade. Too much camber and the plane either does not take a full width shaving or the amount of wood, the shaving, the plane tries to take is more than can comfortably be managed. The issue for me is my desire to have planes that can remove larger amounts of wood. I was tuning up Stanley #5 1/4, 4 1/2, 5 1/2 & 6 planes yesterday experimenting with whether the thinner blade on the 5 1/4 made taking a larger shaving easier than attempting something similar with a #6 with 2 3/8" blade or a # 5 1/2 with a 2 1/4" blade. My base for testing being a Stanely #5 with a hand ground/sharpened blade that has been my go to for stock removal.

Thus far my results have not been conclusive. My 5 1/4 has major camber at this point, so I am not getting a full width shaving, even with the 1 3/4" blade. The 5 1/2 has much less camber and takes a full width shaving, but so far not too thick. I am having a problem with Stanley's fairly small mouths. Blades with large amounts of camber tend to clog the mouth due to lack of room for a large shaving to pass. I am thinking about opening up the mouth of one of my Stanley's, once I figure out which one might be best at taking larger shavings.

Garrett Ellis

10-22-2015, 1:44 PM

you will never get a full width shaving with camber. that's the point of it.

the rougher the operation, the more camber you want. you just want to hog off material. for a scrub/jack/fore plane, somewhere around 8 inch radius is what i usually read. that's what my jack plane has.

for smoothing planes, less camber. just enough to avoid plane tracks.

if you have enough planes, its nice to keep 1 jointer with a square blade for jointing edges, but that's just a preference thing.

ian maybury

10-22-2015, 2:27 PM

It's been said before, and i'd leave it to others more experienced to make recommendations on specific camber amounts Mike (but broadly it's got to correlate with the required maximum depth of cut expected of the plane) - but i think a huge factor in the call is your style of working. As ever in these matters it comes down to setting the tool up to do the specifc job that needs doing.

Many of us these days mix hand tool and machine working - and if that's the case then camber is perhaps more about avoiding corner marks while removing small amounts of material or smoothing - or maybe squaring up an edge.

If on the other hand it's about committed hand tool do everything working then as well as the above the requirement to hog off large amounts of material will arise. This is where heavy camber seems to become very useful - or when the requirement is to create surface texture. I set up my first scrub plane last year (the Veritas one - i just honed up the iron with the stock camber on) and was blown away by how it effortlessly peeled off cuts so thick partially cross grain as to be unimaginable.

It's possible to set up bench planes with heavy cambers to function as quasi scrub planes/to remove more wood, but there seem to be definite limits with these where either a restricted mouth opening or use of a chip breaker (which latter will more or less 'stop' the plane if the chip gets too thick) decides the maximum depth of cut that's realistically possible….

Mike Holbrook

10-22-2015, 2:36 PM

Garret, I understand your reasoning and the convention of a 6-8" radius for hogging and a "slight" camber for smoothing, flat for jointing. I have traced these radiuses onto a plane blade and then tried to grind them in. I can come fairly close. The question even within your parameters becomes the same, exactly what size radius do I use for X width blade. Do I take the weight/width of the plane into consideration. I am not a fan of "scrub" planes as I find the plane designs very light for trying to remove larger amounts of wood. I like a plane with some weight if I am going to be trying to push through tough grain or remove a thick shaving.

It seems to me that the "average" woodworker may not need to remove large shavings to simply level a few boards so the issue may not come up. Lunch box planers are relatively cheap these days. However, over the years I have read many a horror story of how much time it took some fellow woodworker to flatten a bench/table top with hand planes that I am betting were not set up for removing large amounts of wood.

I just took a new experimental class with Chris Schwarz on making sawbenches. The point of the class was not so much to make a sawbench as to learn a woodworking technique for adding legs to all sorts of furniture. We started with 2/2" inch oak boards. We were to plane these into tapered octagons, try it sometime. Suffice it to say, even in a two day course, no one got two sawbenches done, even though making the legs was just about all there was to making the sawbenches. Chris had just one #5 set up to take a large amount of wood. A few months later I made similar legs for a "Welsh Windsor/Stick chair at Country Workshops. I was much better prepared, having set up my #5 Stanley like Garrett mentions. Still there was plenty of room for improvement. There is a reason most chair makers turn the legs & rungs for the chairs they make. I would like to be able to do the job the old way, by hand. I am working on a bench design....Somehow this work was done in the past without all the machines. Drawknives probably did a good deal of the work, but drawknives are mostly for green wood, try taking large shavings from dried wood with a drawknife.

Mike Holbrook

10-22-2015, 3:06 PM

Thanks for your thoughts too Ian. I think I unwittingly responded in my post answering Garrett.

Here is the other issue I have found. I traced some radius on my #5 when I ground it. I can't remember now what that radius was. I know I changed it a little while making it and adjusted it a few times later. I guess I could trace the pattern on another plane blade, but chances are good that blade will be a different width. Derek has apparently tried to resolve this issue by making wood templets to trace onto his blades. Still different blades are different widths, thicknesses.....Even in Derek's more technical approach, he mentions that there is still room for thought in figuring out optimal cambers. My guess is in the past people learned to eyeball functional patterns from other successful patterns, few/none of which exist today. As others have mentioned, the final answer probably will not be a specific radius for the entire width of the blade. I am thinking something with more rounded corners and less radius in the middle. I have a couple planes made years ago by Steve Knight. Steve cut the corners off those plane blades, unless Tom Vanzant, the original owner, did it.

It seems to me that the optimal "pattern" for any plane blade isn't something that can be created with any kind of jig or tool rest out there. I think we are talking hand/eye work. Derek tries to explain his methods for less dramatic patterns in terms of strokes on a specific stone, readily admitting the lack of precision. This is why I think this is a hard topic to discuss but one deserving the time and thought to resolve/improve our methods.

Tom M King

10-22-2015, 3:44 PM

Mine vary from half a thousandth on a 4-1/2 to maybe an inch and a half radius on a Scrub plane. My 8 is straight, 7 maybe one thou. 5 about 10 inch, and a couple of 6's between 4 and 8 thou. Deepest smoother is one of the 3's at 9 thou, to match some old smoother texture. several smoothers between that 3 and the 4-1/2. All of these are either Records or Stanleys. Most of the Records I bought new. I look at the iron protrusion sighting down the sole, and measure shavings. None of this was done all at one time, but on various rainy days over the years. When I use a jig on a cambered iron, it's an old Record with about a half inch ball for a roller.

Daniel Rode

10-22-2015, 3:48 PM

Is your concern to convert a particular camber between blade widths?

I don't think of the iron camber as a particular radius but a particular shape to perform a specific function. This includes the width, the projection and the shape of the edge (flat, cambered, flat with feathered edged, etc). So I first think about what I want to accomplish and then what plane with what type of iron shape will do this for me. I couldn't tell you what the radius is on anything. I mostly start with an idea of what I think will work and adjust from there. Sometimes that adjustment is a little tweak when honing, sometimes it's been regrinding. When I first setup my #5 hogging/scrub plane, I used a camber that was too aggressive and had to regrind flatter.

I'm darn sure no expert, I'm just learning myself, so I might have the whole thing wrong. I seem to have better results when I work by feel than by ruler.

ian maybury

10-22-2015, 3:55 PM

I suspect it again comes down to what the iron is intended for Mike. If the camber is used to square joint the edge of a board then it's got to pay to use a profile that deliveres a predictable response in terms of change of slope/angle/inclination to moving the plane over towards one or other side of the blade. Rounded corners will obviously not be very useful for that, but they do seem to be a very valid option for smoothing.

There may be subtler considerations, but with a scrub plane it's maybe about coming up with the profile that removes the greatest volume of wood for the least effort - while leaving a surface that's a decent starting point for flattening and smoothing afterwards. e.g. no deep or inconsistent gouging or splintering.

I guess there's a lot to be said for a profile using a standard radius that can be applied using a simple holding device that rotates about a point. A CBN wheel though given that it cuts so fast should as you say though make it very feasible to using a honing guide or something to maintain the bevel angle grind back to a marked line to create a custom profile if needed - maybe even (if we're to speak very hypothetically/experimentally) with enough creativity in the set up one that includes concave sections ground off a corner of the wheel.

I've no idea though how unusual profiles like this might perform though...

Mike Holbrook

10-22-2015, 4:03 PM

Good info. Tom. You have some major cambers 1 1/2-4 "is steep. You must work from wood that is not squared or dimensioned? You must grind these by hand & eye?

I have a Record #7 and a 4 1/2 I bought "new" too, which was about all there was at that time, at least within my budget at that age.

Tom M King

10-22-2015, 4:08 PM

323843Here's a picture of the Scrub plane. It's actually used as a SCrubber of dirty beams before I put a good iron in the wood. I'm just guessing the actual radius on that one. Just by hand on stones, for all but the 5, and the old red Record honing guide to start with. I don't have a picture of that guide on here yet. I work with old stuff, on old houses. An example of using several of these planes can be found in the picture linked below. The original panel had rotted away from windows being knocked out of the house for 40 yeARS. I found this board in the attic behind a knee wall. It's hard to find 17" wide Heart Pine boards, so I felt lucky to find this one. It was used as a floor board, and probably stuck behind the knee wall since it was split all the way down the middle. I fixed the split so it could only be seen if I tell you where to look, but only by leaving a hump going all the way along the length of the board. Others have humps too, so that was okay. It had to be straight on the ends to allow for the tongue into the stiles, and to allow the little molding to fit (not yet installed in this picture). If I cut all the hump down, it would have exposed some of the West epoxy in the middle of the panel. Both ends glued together close enough that I could flatten them on down to straight. I used a number of planes on that one panel, but don't remember exactly which ones. Surface texture is from one of the smoothers that matches the adjoining wainscot panels on that one 20 foot long wall.

It's the panel above the electric box: http://historic-house-restoration.com/images/ElamsHouse_Oct._2012_052.JPG

The texture on these steps is from the deep cutting 3, and matches other such smoother texture found on some original boards in that 1828 house: http://historic-house-restoration.com/images/holddownmoldinghead_001.JPG

I hone under running water in a sink on waterstones-currently Sigmas. I judge where I'm cutting by the dark swarf tracks on the stone. The water doesn't wash them off, and when there are is so much marking left on the stone, it goes in the adjoining sink to be quickly flattened back to a clean face.

Jim Belair

10-22-2015, 6:29 PM

My opinion is for stock removal anyway (as opposed to jointing) the ideal camber does result in a full width shaving. If smoothing and taking a one thou shaving, that shaving tapers to zero right at the edges of the blade. And if its a scrub and you're taking off 0.1" per pass, again the shaving tapers to zero at the edges of the blade. A jack plane for moderate removal would be somewhere in the middle, but again, the shaving tapers to zero at the edges. Pick the plane/blade/camber combination for the task at hand.

Tom M King

10-22-2015, 6:43 PM

absolutely. With a heavily cambered iron though, you don't always push the planes sole all the way to the wood surface, depending on how hard the wood is, and the cut you need on any given stroke. It's easy to see how the camber goes all the way across by sighting along the plane's sole with the corners of the cutting edge flush with the plane bottom. I was....can't think of the word....when I saw some video of someone just rounding off the corners. Why use a 2" wide iron if you aren't going to use the whole width?

Doug Trembath

10-22-2015, 6:50 PM

I follow these threads closely, as I do a significant amount of flattening rough sawn slabs for furniture, and rough sawn boards too wide for my jointer and planer. I have tried a few setups with cambered irons. I think that Mike is trying to relate a camber size, based upon a part of a circle, consistently among the different sizes of blades, ie. 3" radius, 4", etc. for all blades. His question, as I read and reread it is "how much camber is right?"

I seldom use it other than finish smoothing, and that's a thou or three. I don't measure stuff like that, it's my best guess.

Obviously a stock Stanley #40 has a radical camber, at least mine does, and will take a heck of a bite at one time. It's great if you need to take severe wind out of a board. It will quickly reduce the high corner, but leave a troubled surface. Using a #6 with a little camber ( just enough to reduce the blade's effective width), leaves a much nicer surface but will still take a significant shaving, and still remove a lot of wood without making it a dedicated scrub plane. One reason I don't really buy in to the heavy camber argument is that I don't really need it, even with distorted timber. I can use a flat blade on rough timber and still take a significant shaving and quickly rough a surface down for a try plane. At that point, who cares about plane tracks?

Another reason is that although I have acquired more than 40 vintage handplanes, I have never found one on the market with any camber applied with the exception of smoothers. I did get one from the estate of a friend of a friend after he passed, a broken 605 that had significant camber, but that is the only one I have personally acquired with any camber at all. It worked great, but not really a whole lot better than a straight blade, hence my questioning the necessity for camber on all planes. I'd be interested to hear your thoughts.

Doug Trembath

Andrew Hughes

10-22-2015, 7:08 PM

I'm pretty sure all my blades have a camber, it's better than a blade with a concave edge.If I really want a straight edeg I pay attention to want I'm doing on the stones.Same with a heavy cambered edge.Just got to pay more attention.

Mike Holbrook

10-22-2015, 11:29 PM

Most of what I have read on SMC relates cambers to radiuses (usually drawn with a pencil/pen compass) as Doug gleaned from my posts. It took me a while to figure out what people meant when they referred to 6-8" cambers so I understand how this might not be crystal for others. The radiuses term at least gives us something to gage what we are talking about doing differently, compared to a straight plane edge.

As I read Derek's post on his Blog., he seemed to be attempting to make a camber that could take a full width shaving. If the entire curve of a given radius is not beyond the planes mouth then it isn't going to take a full width shaving. In the case of major radiuses the distance the blade needs to protrude for the entire camber to be exposed can be large. On my Stanley planes the relatively small mouth openings cause larger cambers to start jamming shavings before the entire camber is exposed, if I can even get the entire camber out of the mouth without it contacting the plane body. I seem to eventually end up with the center of my cambers becoming flattened instead of an exact radius. In the case of smoothing plane blades the curve of the radius can become so small it may not even be visible, or the corners of the blade may simply be relieved. As some one mentions above, if there is no camber at all in the center of the blade we may end up with a concave edge which does not reach the wood.

Tom Vanzant

10-22-2015, 11:58 PM

Mike H...Steve Knight took off the corners of all his irons. IIRC, the intention was to reduce tracks, but all it did was turn a 2" iron into a 1-1/2" iron...it still left tracks unless you cambered the edge. A 2-3/4" wide plane with a 1-1/2" iron never made sense to me, but it was nearly effortless to push.

Derek Cohen

10-23-2015, 1:20 AM

I spent a while on Derek's site yesterday rereading various articles he has written on sharpening, especially since he started using CNC wheels. Like Derek I am largely a hand sharpener who likes to get done with the sharpening and back to cutting the wood. I was interested to read how Derek had evolved in his thinking about how much camber to put in a blade. From what I read I believe Derek himself is still working out precise cambers for specific planes and the blades they use.

Hi Mike

I believe in cambering all blades for bench planes. Some context is required to understand some of the comments in my articles.

Firstly, the amount of camber will vary according to the type of plane. Smoothers get just enough camber to ensure that tracks are not left behind. Jointers get enough camber to enable one to correct out-of-square edges. Jacks and other coarse planes get the most camber so they can cut deeply and quickly.

The requirements for camber vary according to the width of the blade and whether the blade orientation is BU or BD (not a lot here, but just a little caused by geometry).

In every case there is no need to get fanatical. A little too much camber on a smoother will reduce the width of cut. So correct it next time. A shallower or deeper camber on a jack is the difference in efficiency, but may also be a decision based on then wood (some is more brittle).

When I wrote the article on the BU cambers, this was actually ground-breaking stuff at that time. It seems so obvious today, but at that time there was not an efficient method to camber BU blades, and so many just left them straight. The method (of a secondary microbevel on a low primary) was so novel that it became a topic presented at the WIA show that followed after. And yet I would go back now to those early articles and want to re-write them for clarity and perspective ... or just because I have better methods today. No time.

What I must do is correct a method for cambering a jack or scrub plane. I got away with it back then, but it is not recommended now. What I did was grind an 8" camber on a straight edge (using a template - the template is good. Keep this). What one should instead do is grind a flat (not bevelled) radius first, and then bevel it (today I do this on a 8" grinder. Many years ago I used a belt sander). Grinding the bevelled camber from the flat places the steel at risk for burning (I would do it slow and cool, but this does not come across). Grind the radius first, then add the bevel = less steel to remove = less heat.

This is wrong technique...

http://www.inthewoodshop.com/WoodworkTechniques/GrindingNirvana_html_m7bc2497c.jpg

Instead, grind away the waste first to create the camber, and then bevel ...

http://www.inthewoodshop.com/ShopMadeTools/BuildingaJackPlane_html_48ba8327.jpg

Regards from Perth

Derek

Pat Barry

10-23-2015, 8:05 AM

Camber on a plane blade results in scalloped cuts. That is what you want for heavy stock removal, or should I say, you don't care if you get some scalloping because you will be cleaning it up anyway. Otherwise, the whole concept of camber is really hooey. You may want the edges of the blade slightly rounded so as not to dig in and leave tracks but otherwise there is no reason for camber. Take for example edge jointing. Why in the world would you strive to make a scalloped edge? You want that edge as straight and flat as possible. Take for example a tabletop which you expect to finish to a fine degree - you certainly don't want scalloping there, even if its a thou or two. Again, round over the very corners but give me a flat blade all day long.

Derek Cohen

10-23-2015, 8:29 AM

Pat Barry

10-23-2015, 10:35 AM

Hi Pat

The camber on a smoother is so slight that the surface left looks flat. Almost all of the camber is at the corners. The centre is almost flat. It it was actually flat (and you just rounded the corners) then you would be hard pressed to avoid some angling on the surface tops.

The camber when jointing edges is to enable you to "steer" the blade when jointing individual edges that are at different angles. If I was match planing, then I would use a flat blade. Again, the camber is very slight.

Regards from Perth

Derek
Interesting - yes, just round over the corners is what I'm saying - - you can call that a bit of camber on the corners if you wish
Two questions for you though: "hard pressed to avoid some angling on the surface tops" - are you saying that you would tend to cause one side or the other of the blade to cut a bit deeper than the other without the camber?
Second question: "he camber when jointing edges is to enable you to "steer" the blade when jointing individual edges" - how do you mean steer the blade? somehow favoring one edge over the other? I'm having trouble picturing this

Mike Holbrook

10-23-2015, 11:00 AM

Hi Tom, yes I still have those two planes. I also find the reduced edges unnecessary, like you say reducing the angle on the corners but leaving the corners does much the same thing as 90% corners. I considered regrinding those blades now that I have CNC wheels. The reduced edge size, as you say, does make those blades slide nicely. I have quite a few 2" blades I got in my close out deal with Steve and a couple, almost 2" blades, made for HNT Gordon, that I picked up at Highland Woodworking on a close out sale. I probably will leave the blades on the planes Steve made close to how they are, just rounding the corners and adding a slight camber. Thanks for your thoughts/clarification on those blades.

Derek thanks very much for the update on your thoughts regarding grinding bevels. Derek's picture shows a stone wheel which I don't use these days. I use CNC wheels as I believe Derek typically does. I realize stones are more commonly used by a larger number of posters. I also know how people worry about over heating blades, including myself.

The first cambers I did followed Derek's current suggestions. I ground the radius then made my hollow bevel. Yesterday though, I tried just grinding the radius and hollow bevel at the same time. Like Derek mentions, at first my blade heated up due to the larger surface being ground even with a CNC wheel. Then I tried grinding both at the same time with light pressure against the wheel. I was very surprised to find out how large a difference the amount of pressure I made against the wheel translated into more heat. Once I eased off on the pressure against the wheel it seemed I could not make the blade heat up at all using a 180 CNC wheel. I make this point because I think my bad habit of pressing too hard against a stone grinder has caused me a large number of issues in the past, and still can when I forget. I believe I got into that habit trying to grind/regrind bevels on A2 BU plane blades on a Tormek. The Tormek was so slow it was hard to tell if it was working at all which caused me to use way too much pressure in an effort to make visible progress. I was making so much pressure I believe I was moving/bending the rod that holds jigs enough to throw things off. I was happy to discover that reducing the pressure against my wheel yesterday did not reduce how fast the wheel cut nearly as much as I thought it might. I have a SB (Stuart Beatty) angle setting jig that I use to set my SB tool rest's angle to the wheel. Oddly enough the 25 degree want touch the wheel due to the 65 setting hitting the wheel first, so I have been using the 30 mark/curve, which removes a little less metal. So far the greater angle has seemed to cut reasonably well.

In regard to major stock removal, I think a scalloped surface actually helps. The scallops obviously make an uneven surface but go deeper in the process. Removing the scallops is easy to do using a plane with a less dramatic camber. In regard to smoothing planes, I think we start getting into the question of which side of "perfectly straight" we want to have our error, knowing that there isn't actually any perfectly straight edge. I find slightly convex plane blades work better than slightly concave. We want a "flat" surface on the ends of dovetail tails too, but many people make them slightly concave as this error is preferable to slightly convex.

bridger berdel

10-24-2015, 1:46 AM

Most of my planes have slight camber. For the 2" wide size- #4 & #5, I keep three or four blade/chipbreaker sets at various cambers. I have never measured radii of them, just if I need more camber than I have one set up for I'll grind a curvier one. Mostly if I'm doing scrub/fore/jack work I use the cambered blades in the #5 and leave the #4 set up as a smoother, but that isn't a rule or anything....

ian maybury

10-24-2015, 5:58 AM

On flatness/straightness of edges, and the rabbit hole that is sharpening.

I run a modifed Veritas Mk2 honing jig on very carefully and frequently flattened waterstones, and am confident in saying that the method if needed produces edges which if they are not dead straight are undetectably close to it. That's using the straight/cylindrical roller set up.

I switch to the camber roller (or even a narrow roller Eclipse type) on other jobs where less (or more in the case of the latter) camber is required.

One often overlooked advantage of the Veritas (or any other very wide roller) guide is that it has the potential to produce very straight edges. This because it creates a tipod/prevents the blade from tipping side to side. I can hand sharpen, but there are definite precision related advantages to using a jig...

Robert Engel

10-24-2015, 7:30 AM

Wow am I missing something or is being way over thought?

To me its simple: ease the corners on my smoothers to eliminate tracks and keep a couple variably cambered blades around for quick stock removal.
I don't see the point in any camber at all on a smoothing plane unless you want to see tracks.

I keep a cambered blade for a 4 and a 6.
On the 6 I don't know what the radius is - its an arc but not as much as a scrubber.......what's the diff?

I just eyeball it when grinding but you can make a pattern.

Stewie Simpson

10-24-2015, 7:55 AM

Is there any historical data that recommends you camber and/or ease the corners of your irons on all of your bench planes.

Stewie;

Warren Mickley

10-24-2015, 8:11 AM

Derek Cohen

10-24-2015, 9:58 AM

Warren described it well, better than I did. "Camber" on a smoother should not imply "rounded", since round leaves a scollop. The ends of the blade indeed "feather", which means they fade to nothing.

Regards from Perth

Derek

Mike Holbrook

10-24-2015, 10:48 AM

Yes, Robert, you are missing something. For a smoother a rounded edge means the cut will feather to nothing at the edge. If you just round the corners, the edge of the cut is not as abrupt as a flat edge, but still noticeable nonetheless. Rounded tracks instead of square tracks. In addition the problems with having the iron slightly tilted to one side are much more severe with an iron that has rounded corners than one which has a nice sweeping curve. If you are not planing boards that are wider than the iron, it does not matter very much.

Yes, I think what Warren is saying is the crux of the situation here. There is some point at which, starting backwards with the smoothing plane, the blade curve becomes indistinguishable via the human eye. Like Warren says the "edge" made by the two corners of the blade start to fade away visually and even tactilely. It seems to me that approaching that curve on the edge of a smoothing plane is the ultimate in sharpening technique. It ultimately does not matter how sharp or straight a smoothers blade is if it leaves tracks does it? Sure maybe we can sand or scrape the tracks away but that is more steps and more work. Isn't one of our objectives to produce more interesting work than machines produce? Is a "perfectly' flat surface more interesting than one that hints at the techniques used to create it? As I know has been argued before, at what point does leveling of a surface go beyond utility and start becoming fruitless?

I have seen what I would term visually "perfect" surfaces made with very sharp drawknives. At least in my somewhat warped mind I do not think the surface made by a very sharp blade can be improved on. I am more interested in what the surface I make reveals in the wood visually. As I believe many on these pages have concluded over the years sanding or scraping ends up roughing the surface to obscure visual plane tracks. Do we want to leave a slightly rough surface and cover it with finish? Does this type finish obscure or embellish our work? Isn't that technique trying to copy what machines do? For me hand tool work is more "impressionistic" and should by definition impress via techniques that paint a broader less "perfect" picture. For me the beauty of work done with hand tools isn't in how close it comes to what a machine can do, it resides in the mystery and visual suspense it creates that can't be created with machines. Still we want our work to be at least as functional as machine made work so we do not want sharp edges or surfaces that are not at least as functional as machine made ones. Shouldn't we be attempting to do more than machines instead of following some misguided path that approaches but never quite achieves the more simplistic "perfect" work a machine does?

I learned some interesting things in Windsor Chair classes. Talented chair makers like Peter Galbert avoid sand paper and even scrapers, considering them indications that the drawknife and maybe spokeshave work were not done as well as they could have been. Galbert and his assistant seemed to feel that even picking up a spokeshave indicated that they may have made a stroke they had to correct with a "lesser" tool. They seemed to prefer to "paint" with a broader brush and longer strokes. I know that some of the more experienced hand plane people feel the same way about hand plane work. In chair making the objective isn't to make a "perfect" surface. Visually the maker wants the observer of the work to be able to tell that the work is not quite perfect, hand made. Isn't "perfect" a machine made characteristic that we should avoid instead of try to emulate?

Obviously, I still have more to learn from guys like Warren and Derek who are better at painting with broader strokes both with hand tools and words.

Stewie Simpson

10-25-2015, 8:09 PM

Therefore, I sharpen more camber into a blade for a low angle bevel-up plane than for a bevel-down plane to achieve the same functional amount of camber. http://www.finewoodworking.com/item/29774/how-much-camber-should-be-in-plane-irons

Kees Heiden

10-26-2015, 5:35 AM

Just as an aside, a historical detail.

In the 17th century the Dutch smoothing planes had a round corner on one side of the bottom of the plane, with a similar round corner grinded into the blade. It looks a bit like a rabbet plane with a round edge instead of a square one. The current idea is that the plane was used on the last passes over the wood, going in length wise strokes from right to left, thus eliminating the tracks from the square corner on the other side of the edge.

324104

324105

Robert Engel

10-26-2015, 7:33 AM

Warren Mickley

10-26-2015, 9:13 AM

I think the ideal for a smoothing plane is nice rounded arc all the way across the width so that it cuts roughly .001 in the center and nothing at the very edge. That way the feathering is very smooth, gentle all along, not concentrated in the last 1/8 or 1/4 inch of the cut. In addition the penalty for a slight lateral adjustment problem is merely that the cut is a little off center in the plane, not that the plane is making an angled cut as is the case for a "flat" edge with upturned corners. In fact with an arc shape, how the cut is centered in the plane is an extremely sensitive diagnostic tool for lateral adjustment.

For a jointer plane, a arc shape gives a much more effective tool for flattening an edge that is very slightly in wind.

Mike Holbrook

10-26-2015, 1:48 PM

Good link Stewie, to the Fine Woodworking article/video. I think the picture of the smoothing plane blade, against a square with light behind it, illustrates what Warren is saying. The curve in the blade on a smoother may be so small as to not be visible without the square and extra light. "Historically" unless the "historians" were checking blades in the same manner the curve might not be noticeable. It seems to me that very few used/flea market finds have blades that are in the condition that a tradesperson 100 or more years ago would have left them in.

Warren makes a great point about the virtues of a gradually curved vs flat plane blade surface, in my humble opinion. I believe the same principals apply as we move towards planes set up to do medium and coarse work.

Jim Koepke

10-26-2015, 2:03 PM

It seems to me that very few used/flea market finds have blades that are in the condition that a tradesperson 100 or more years ago would have left them in.

There was a period of change in the craft trades and a couple of major wars that interrupted the transference of knowledge and tradition through the period these older tools have existed. During my lifetime I have met many people who though a blade could be brought to full sharpness on a coarse grinding wheel. It doesn't surprise me that so many of "grandpa's old planes" were taken off a shelf to smooth the edge of a sticking door. Certainly the first thing such a tool needed was a run over the bench grinder, wiping away any of the historical remnants of sharpening.

jtk

John Sanford

10-26-2015, 7:43 PM

Excuse me for being dense, but why would one use CNC, i.e. Computer Numeric Controlled wheels unless you have a CNC grinder? Do you mean CBN, i.e. Cubic Boron Nitride, wheels?

Mike Holbrook

10-27-2015, 12:04 AM

Sorry John, yes CBN wheels.

Mike Holbrook

10-29-2015, 10:09 AM

I wonder if others have the issue of a cambered blade not fitting well in the standard/small mouth of Stanley planes? Admittedly I may have been experimenting with too much camber. Still I am having issues, particularly with LV's blades made for Stanley planes, which I believe are slightly thicker. I have been considering increasing the mouth size on the planes I plan to use with the more cambered blades but I thought I would ask what fellow posters have done to resolve issues of this nature first.

I have Veritas BU planes which I have been planing to use as my less cambered planes. Considering the easier to adjust mouths on these planes though I may have things backwards. There is the issue of the thicker wider bevels that need to be ground into BU blades to achieve cambers. I am aware of Derek's method of achieving this with a secondary bevel. I am also aware that CBN wheels grind faster hollow grinds and might make cambering BU plane blades a more approachable goal.