The secret to cambering Bevel Up plane blades

[Derek Cohen (Perth Oz)]

My friend Larry is adamant that bevel up planes cannot be cambered as easily as bevel down planes

“… for the low angle blade profile to have the same projection as the common pitch plane it would have to have more than three times as much camber…”

Larry has a point. My own experiments have shown that BU planes require more camber than BD planes. It is for this reason that cambering BU planes has been considered a weakness in the design. Hopefully we can put an end to this view now. The fact is it is dead easy to camber a BU blade … it still will require a larger camber, but this is not a significant issue as long as you follow one simple rule. Let me show you how it is done.

The Way to Camber Bevel Up Blades.

Here it is in a nut-shell … grind the primary bevel on all plane blades to 25 degrees. Don’t try to camber any blade that is greater than this, such as one with a 38- or 50 degree primary bevel (such as those available as optional purchases through Veritas). The latter blades are perceived to be a shortcut to honing, but this is an illusion.

BU planes blades are best prepared with a microbevel. There is no difference if this is added to a 25-, 35, or 45 degree primary bevel. However, the steeper the primary bevel, the more steel to remove when honing/grinding a camber. With a 25 degree primary bevel there is relatively little waste to remove. With a 50 degree bevel … well, you’ll drive yourself insane trying to do so..


What kind of camber do you want?

Cambers vary from a .001” thin shaving on a finish smoother to that of the “traditional fore/jack plane used for roughing would have about 1/16" of camber”, as Larry notes. Mmm … can a BU Jack produce a cambered shaving that thick? Easy-peasy!

To illustrate that there is very little extra effort in preparing the camber on a (bevel up) Veritas Low Angle Jack compared to, say, a (bevel down) Stanley #5 ½, I prepared the following tutorial.

What I do

The first step is to start with a blade with a 25 degree primary bevel. I do my flat grinding on a belts sander on which I built a jig similar to a Tormek (this was published in a past FWW magazine). If I have to remove a lot of metal, I will use a 40 or 60 grit belt. This runs quite cool.

Here is an example of a 25 degree straight grind on the belt sander …

The second step is to construct a template for grinding the camber.

Prepare a block of wood the same width as the blade and mark off 1/16” at each end, then draw an arc across this. Remove the waste, so ….

Mmmm… I think I took off a bit more than 1/16”. Looks like 5/64”.

The completed template looks like this ..

and

Adjusted to grind a 25 degree bevel, it works like this …

The result is a cambered 25 degree primary bevel ….

And, yes Bugbear, the camber does indeed match the template! Look …

Honing the Secondary Bevel

The aim is now to add a secondary microbevel of 35 degrees. This will create an included angle of 47 degrees, which is close to the 45 degrees of the typical bevel down cutting angle.

To do this I used a Veritas Honing Guide Mk II (with camber roller) and Shapton waterstones.

The honing guide requires a little modification. Draw a line at the blade stop to help determine the 35 degree setting. Users of this honing guide will understand this instruction.

The Shapton waterstones used were, in order, 1000/5000/8000/12000.

Here is the microbevel that was produced …

And here is the camber as seen from the mouth of the LA Jack …

Soooo .. what about the shavings? None of this means anything without any shavings ..

Here is a thinnish shaving …

… and a thickish one …

It is possible to go thicker still, but I did not do so here.

Instead, I took some pictures of cambered shavings on other BU planes….

This is one on the Veritas BU Jointer on the edge of a pine board. Look at the thick center and the tapered edges. The shavings are identical to those taken by a cambered Stanley #7. I am sure that David Charlesworth would be proud.

And here is a finely cambered smoother shaving…. Tasmanian Oak planed by the Veritas BU Smoother.

What is relevant to note about these last two shavings is that the secondary bevel on each is 50 degrees. Further, these were created without a template – simply by extra pressure on the edge of the blade.

Following the 25 degree primary bevel preparation on the belt sander, the honing guide was set for a 50 degree micro secondary bevel. Ten strokes on the 1000 were enough to create a wire edge across the bevel face. An extra 5 strokes each side was sufficient to create the camber for the smoother, and 10 strokes for the jointer. The 5000 followed with 10 strokes to center, left and right. Ditto 8000 and 12000 ‘stones. The wire edge was removed on the 12000.


In conclusion

I agree with friend Larry that the camber on a BU plane needs to be steeper than on a BD plane. However I do not view this to be a negative factor. It is just a difference in honing, and one that one just accepts as part of the honing method when using these planes. When the secondary microbevel is added to a 25 degree primary bevel, the effort level is low. Camber away without fear.

Regards from Perth

Derek Cohen
October 2007

 

[Chris Knight]

Nice job Derek. It is a fearsome looking camber I must say (practically a scrub plane) and the shot of the mouth makes it look even more pronounced - although that might just be a shadow effect.

Still the shavings speak for themselves - especially the last picture of Tasmanian oak.

Thanks for the useful guide.

 

[Philly]

Excellent -thanks for taking the time to document this, Derek!
There has been quite a debate recently on bevel up planes, some folks writing them off as the Devils' Planes! :roll: Needless to say, the results speak for themselves, though.
Best regards
Philly

 

[Wiley Horne]

Derek,

Excellent method! And fine exposition and photos, too. Would work well for any blade, BU or BD, it appears.

I have one question. When it comes time to resharpen, what do you recommend....just regrind the primary bevel enough to get past the wear on the back side? Or do you operate directly on the back side to deal with the wear?

Thanks, Wiley

 

[Paul Kierstead]

Excellent illustration and article! I am glad someone is addressing this and making straightforward and accessible.

Here it is in a nut-shell … grind the primary bevel on all plane blades to 25 degrees. Don’t try to camber any blade that is greater than this, such as one with a 38- or 50 degree primary bevel (such as those available as optional purchases through Veritas). The latter blades are perceived to be a shortcut to honing, but this is an illusion.

It is very nice to see this re-enforced. I really think people get too caught up on the primary bevel.

 

[Derek Cohen (Perth Oz)]

When it comes time to resharpen, what do you recommend....just regrind the primary bevel enough to get past the wear on the back side? Or do you operate directly on the back side to deal with the wear?

Hi Wiley

You have asked the Big Question. The short answer is that I am not certain, and I have two areas to explore.

When it comes to sharpening, I much prefer a hollow grind on a grinder, followed by freehanding on waterstones. This is clearly very different to the above process but it is my preferred method for BD blades and chisels. Further, I would like to avoid a micro back bevel (such as the Ruler Trick) - not because I disaprove of it. I think it an excellent technique under other circumstances - because I like to strop blades as I work, and this is difficult to do with backbevels, both front and back.

So my first impulse is to follow this with BU blades. That is, hone the back of the blade sans micro backbevel. The trouble is that BU planes create wear on the back of the blade, and the question is how does one get rid of it?

One could just regrind the primary bevel and add a new microbevel. But this seems a lot of work and wasteful of steel.

One could flatten the back of the blade, for example, by regular stropping as one works. This is what I am doing at present, but I am still evaluating how well it works. My concern here is that one may inadvertantly over time be creating a curved back.

The other alternative is to deliberately add a micro backbevel (using DC's Ruler Trick), as this will circumvent the wear bevel. I have done this in the past, and it works, but it means that I cannot strop the back of the blade (to refresh the edge).

So sorry no definite answer as yet. All the above work. The question is which one works to provide the greatest efficiency. I hate sharpening and all I want is to find a simple and efficient method.

Regards from Perth

Derek

 

[David C]

Derek,

Nice shavings, proud indeed ~;-)#.

For resharpening I would suggest you have a look at my plane sharpening dvd. Your method above is getting very close to my sharpening routine except I use a £5 guide and only two stones,
Coarse 800 king and polishing 8,000 or 10,000 grit King.

The use of 2 stones only is made possible by the two degree lift when moving from coarse to polishing on bevel.

Re sharpening is just a case of how many strokes does it take to get a tiny wire edge in the centre, where most wear will have taken place. And then applying same number of strokes to the four other points across the blade.

Shaping and resharpening get even easier if you grind at 23 degrees.

Wiley,

When regrinding, leave a sliver of the previous honing as this contains the shape or squareness of the edge. There is no reason to grind up to the edge unless you have a big chip. This just shortens life of blade.

Despite the fact that so many are suspicious of it, the ruler trick works for all edge tools except bench mortice & paring chisels.

Please forgive a small rant here. I am fed up with the few rude and obnoxious people on knots forum who mock and misrepresent my methods without even taking the trouble to understand them.
The intellectual effort required seems to be beyond them?

This forum is generally a much pleasanter place to post ~#

best wishes,
David

 

[Philly]

This forum is generally a much pleasanter place to post ~#

best wishes,
David

That's just how we like it, David!
Philly

 

[Derek Cohen (Perth Oz)]

Hi David

Thank you for the vote of confidence. And, yes, this is a much more civilized and friendly atmosphere than some others! Do not go There (you know where) if you suffer HBP.

Incidentally, the reason I have used 4 stones is more a case of "new stones and getting to know them". I previously would do a 1200 and 8000 King. These Shaptons are just great for the feedback they provide. I am indeed familiar with your sharpening video - own it and have watched it many times. Where do you think I learned to hone cambers by numbers?

I took a few more shavings with the LA Jack (my previous effort there was to demonstrate the process and I stopped short of deep, fore-plane-type shavings). These now were about 1 1/4" - 1 1/2" wide and 1/32" thick.

Regards from Perth

Derek

 

[dchenard]

Here it is in a nut-shell … grind the primary bevel on all plane blades to 25 degrees. Don’t try to camber any blade that is greater than this, such as one with a 38- or 50 degree primary bevel (such as those available as optional purchases through Veritas). The latter blades are perceived to be a shortcut to honing, but this is an illusion.

BU planes blades are best prepared with a microbevel. There is no difference if this is added to a 25-, 35, or 45 degree primary bevel. However, the steeper the primary bevel, the more steel to remove when honing/grinding a camber. With a 25 degree primary bevel there is relatively little waste to remove. With a 50 degree bevel … well, you’ll drive yourself insane trying to do so..

Not sure I understand here...

It seems to me that if you put a heavy camber on a 25 degree iron, you will have a lot more steel to grind away than with a 50 degree blade. Just look at the length of the bevel... Not that one would want to put a heavy camber on a high angle iron (after all a plane using that heavy a camber is for roughing anyway), these are for final smoothing and therefore should have minimal camber.

As for irons with a high primary bevel (38 and 50 degrees), these are not a shortcut to honing if you do it freehand. But if you want to put a 35 degree micro-bevel on a 25 degree blade, you have no choice but to use a honing jig... Wouldn't you know, I've found one advantage of using a honing jig! :shock: :mrgreen:

Still, I prefer honing freehand (not the topic here, so I'll keep it at that) :wink:

The other DC

 

[Derek Cohen (Perth Oz)]

Denis

Trying to camber a 50 degree full face bevel is very hard work. There is considerably more steel to remove than when the primary bevel is a low 25 degrees and a 50 degree secondary bevel is added.

I spent a long time fighting with this area. I much prefer honing freehand on a hollow grind. This is fine for bevel down planes and for most chisels. It is also still the method I employ for low angle bevels on BU planes, such as the LA Jack when used on a shooting board (straight bevel) and across grain for flattening panels (slightly cambered bevel). An example of the latter is below:

On the other hand I use high cutting angles - 50 degrees bevels for a 62 degree included angle - when smoothing or jointing as the timber I work is hard and has much interlinked grain. It is simply impractical to freehand these blades, and so I have come to accept that these must be created with microbevels using a honing guide.

If you want to freehand a 50 degree bevel, go ahead - it can be done (I have done it) - but you are essentially restricted to a straight edge. Adding a camber to a 50 degree bevel face would take you hours to do freehand, and then you are faced with the "fun" of maintaining it.

Regards from Perth

Derek (one of the DC club)

 

[dchenard]

Denis

Trying to camber a 50 degree full face bevel is very hard work. There is considerably more steel to remove than when the primary bevel is a low 25 degrees and a 50 degree secondary bevel is added.

This is the part that I don't get... A 3/16" thick iron has a bevel that's 0.443" long at a 25 degree angle, and 0.245" with a 50 degree angle. Seems to me there's nearly twice as much steel to remove on a 25 degree bevel iron compared to a 50 degree one, for a given camber angle. Either your statement is incorrect, or I'm missing something...

I spent a long time fighting with this area. I much prefer honing freehand on a hollow grind. This is fine for bevel down planes and for most chisels. It is also still the method I employ for low angle bevels on BU planes, such as the LA Jack when used on a shooting board (straight bevel) and across grain for flattening panels (slightly cambered bevel). An example of the latter is below:

On the other hand I use high cutting angles - 50 degrees bevels for a 62 degree included angle - when smoothing or jointing as the timber I work is hard and has much interlinked grain. It is simply impractical to freehand these blades, and so I have come to accept that these must be created with microbevels using a honing guide.

Impractical? Not really, how is that so? Is it more difficult to put a microbevel freehand on a steep beveled iron than on a low bevel one? Yes, but it can be done without too much trouble.

If you want to freehand a 50 degree bevel, go ahead - it can be done (I have done it) - but you are essentially restricted to a straight edge. Adding a camber to a 50 degree bevel face would take you hours to do freehand, and then you are faced with the "fun" of maintaining it.

Regards from Perth

Derek (one of the DC club)

Why is it that one is restricted to a straight edge if doing a 50 degree iron freehand? Not trying to start an argument, just trying to understand, as I do use a gentle camber on my 50 degree iron, and do the micro-bevel freehand... Not as easy as with a lower beveled iron, but doable, the technique is the same...

Cheers,

DC-C (for Canada)

 

[Wiley Horne]

Hi Denis,

I believe Derek's point about grinding camber on the steeper-angled blade is that you're getting far more quickly into the meat of the blade. In other words, this is solid geometry, not plane geometry. You're grinding the same linear distance, say 1/16", regardless of bevel angle. But with a 25 degree blade, the camber takes you ankle deep into steel; with a 50-degree blade, you get up to your knees, and quickly.

However, I like where you're going with your inquiry. Caution: opinion follows......It strikes me that the best compromise on dealing with 12-degree BU blades is simply to take enough metal off the primary bevel each time to remove the wear mark on the blade back. In the overall tradeoff--with 12 degree blades--I would prefer to maintain as much clearance as possible, and sacrifice metal to do it. Now if it were a 22.5 degree Holtey BU, I think I would prefer to work the back directly, because of the greater clearance available.

I think Derek is almost there in his method. The key is to remove steps from the resharpening procedure. One way to do this would be, as Derek says, to make the first grinding at 25 degrees. And do the microbevel thing. But on the first resharpening, go back to the grinder and grind to 35 degrees, skip the microbevel, and freehand hone. On subsequent resharpenings, go back to the grinder and remove enough metal (est. approx. 0.001" of primary bevel) to clean up the blade back, and freehand hone.

The belt sander is a good procedure, and Derek's setup looks to be very fast. In my case, I hollow grind cambered blades freehand on a simple vertical bench grinder, and that will work also.

I agree with you that freehand honing cambered blades and gouges is simply a matter of practice. You develop the feel and the rhythm, and it goes quickly once you've done that.

In short, I think Derek is about there, and that he need only rely more on grinding in subsequent resharpenings, after the initial setup.

Wiley

 

[AHoman]

Please forgive a small rant here. I am fed up with the few rude and obnoxious people on knots forum who mock and misrepresent my methods without even taking the trouble to understand them.
The intellectual effort required seems to be beyond them?

David,
One of the primary objectors to the ruler trick is the same fellow who a few months ago deplored the use of shooting boards, claiming that if one couldn't just put a board in a vise and plane to a line, then one should probably just use power tools before resorting to a shooting board.

Some of these people who object so strongly to shooting boards and the ruler trick are borderline trolls who have never posted pictures of their work to back up the notion that anyone should take their opinion any more seriously than mine (I am a rank amateur).

In my recent adventures in woodworking, I have enjoyed again and again the accuracy that I get from the use of shooting boards as outlined in your books. I've used the ruler trick on occasion, but I've also learned to prepare the backs of irons in a more traditional manner.

It is invaluable to my continued search for ways to make the most of my brief woodworking time that I can occasionally read posts by you on these forums. Please don't leave! For every close-minded soul there are probably 10 or 15 who admire your contributions and just read the posts but don't get mixed into the fray by posting, especially on Knots.

I'd like to tell a story about the influence that your publishing has had in the world.

I started reading your books in January 2006. I teach (humanities and German) at a school that has a woodworking component to its sculptural arts program. In tenth grade the students usually make some kind of project with dovetails, usually a small stool or box. I showed your books to my colleague who teaches sculptural arts, and he almost immediately decided to build shooting boards for the students, and to tune up our fleet of Stanleys with Hock irons. Just for fun, during my free periods I've assisted him twice with this six week lesson -- the second one is 3/4 of the way through and we are having a blast. The students use the shooting boards to prepare their boards to make small dovetailed boxes out of cherry and walnut. They love using the shooting boards, and we feel that it is a safe way of letting them prepare their own boards for the project. Someday, we're hoping that a particularly inspired group of students will want to take a special elective and make something with twisted dovetails! At any rate, your publications have been an inspiration for our tiny little school in rural Vermont, thousands of miles away. We have one student who is interested in furniture design and would like to take a gap year (that is a year between high school and college) in England to explore this passion -- he is looking into a variety of programs.

Sorry for going on for so long, but when I read the discouraged note in your email, I felt that I had to pipe in some encouragement.
Best regards,
Andy

 

[dchenard]

Hi Denis,

I believe Derek's point about grinding camber on the steeper-angled blade is that you're getting far more quickly into the meat of the blade. In other words, this is solid geometry, not plane geometry. You're grinding the same linear distance, say 1/16", regardless of bevel angle. But with a 25 degree blade, the camber takes you ankle deep into steel; with a 50-degree blade, you get up to your knees, and quickly.

Hi Wiley,

Pardon me for being insistent, but the statement that one will remove more steel on a 50 degree bevel than on a 25 degree bevel just plain doesn't work. Do the geometry: in an ideal world one will remove nothing at the middle of the iron, and go gradually to a camber of say, 1/16", same for both irons. Except at the middle where one removes nothing, at every other point on the curve you will remove more steel with the 25 degree bevel than with the 50 degree bevel iron. Compute the cross-section of the metal to be removed, you will see for yourself, the 25 degree iron needs 0.00277" of cross-section removed at the edges of the iron, whereas the 50 degree bevel one will require 0.00153" removed, or just a tad more than half as much as for the 25 degree bevel. And at any point on the camber more metal will need be ground off from the 25 degree bevel.

I have no qualms about the rest of the post, I do actually like it. I use a different approach in honing my irons, which I think is more efficient, but to each his own. It's just the statement that more steel is removed from a 50 degree bevel compared to a 25 degree bevel one just doesn't work. I'll be happy to be proven wrong, but I don't think I will, sorry to say...

Cheers,

DC-C

 

[Wiley Horne]

Denis,

I'll write you offline, as I have unwisely jumped into the middle of Derek's story with an explanation--when he is infinitely more qualified than I to explain his results!

Wiley

 

[Derek Cohen (Perth Oz)]

Hi Denis

Let me start by saying that your questions are good ones. Even more than good - they are important and must be asked and answered.

The problem centres around the grind (a term I prefer when removing metal rather than polishing it) a significant camber on a bevel up blade. And to take this the important next step, to do so on a BU blade with a high bevel face, such as 50 degrees.

It is contended generally that a BU blade requires a greater camber for the same effect than a BD blade. This is due to the geometry of the bed, 12 degrees for BU and 45 degrees for BD.

It is my contention that there is less metal to remove - which makes the process viable - on a BU blade with a 25 degree primary bevel and a 50 degree secondary (micro) bevel. The foundation for this argument is that a microbevel is .. well, micro .. and a camber on the full face of a 50 degree primary bevel has considerably greater volume.

I would suggest that you try cambering a full face 50 degree bevel by hand and, if you can, do the same with a 50 degree micro secondary bevel on 25 degree primary bevel , and report back your experience.

Keep in mind that we are talking about creating shavings for not just a smoother, but especially for a fore plane - so see the camber profile that is needed to do this. The camber resembles that of a scrub plane with a BD configuration.

Regards from Perth

Derek

 

[David C]

Andy,

Thank you so much for that encouraging story!

David

 

[AHoman]

Andy,

Thank you so much for that encouraging story!

Now we will just have to see what Derek's influence will be on our woodworking program -- will it be bevel-up planes, or will we have the kids make their own dovetail markers? (Or will I have them read Viktor Frankl?)
-A.

 

[promhandicam]

Pardon me for being insistent, but the statement that one will remove more steel on a 50 degree bevel than on a 25 degree bevel just plain doesn't work. . . . Cheers, DC-C

Having read through the whole post, I think that, in your own ways both Derek and Denis are correct.

In the initial set up of converting a blade from straight to cambered then yes more steel has to be removed if you are grinding a 25 degree bevel as opposed to a 50 degree bevel. However once the basic shape has been produced, when it comes to sharpening, less steel will be removed if you add a secondary bevel onto a 25 degree primary bevel than if you are trying to hone the whole of a 50 degree face. Perhaps the following will illustrate what I'm trying to say:

The red lines indicate where the iron would be honed to get a 50 degree angle.

I hope this helps,

Steve