Experimenting With The Grimsdale Sharpening Method

[Steve Branam]

I've been following discussions over on a couple of UK hand tool forums regarding free-hand sharpening. One method in particular appealed to me for it's simplicity. To some it's pure heresy: a convex bevel .

So I gave it a try. I wrote up a 2-part blog post on it, including a video at the end demonstrating it: http://www.closegrain.com/2010/04/grimsdale-method.html.

Judge for yourself!

[Rob Fisher]

I think it is Odate who talks about doing something very similar. Seems to make sense to me for free hand sharpening.

Rob

[Harlan Barnhart]

I do that to some degree when I am in a hurry or feeling lazy. Generally my bevels gradually increase until I grind again.

[Russell Sansom]

My new Barr chisels arrived sharpened this way ( convexly ). I haven't gotten the chance to try them yet, and I assume I'll reshape them to my personal hollow grind when they need to be reground. After the initial shock and the initial resistance to the idea, I realized that here they are! I might as well give them a try. At times the expediency of sharpening this way would be quite welcome.

[James Taglienti]

About 80% of the old socket chisels I find have a convex bevel. If I'm going to use it, I usually grind it out. I don't think it would affect use- might just make the edge stronger?

[lowell holmes]

Like they say "Different strokes for different folks".

[Robert Rozaieski]

I don't think it's heresy at all. If you look at almost every old oval bolstered mortise chisel that you find in the wild, almost every one has a distinct convex bevel. In fact, this is so common, one has to believe that the convex bevel was added intentionally over multiple sharpenings during use rather than just by some ham handed amateur who didn't know what they were doing. Maybe because the angle increased gradually due to the craftsman not wanting to sharpen the entire bevel, or maybe they really wanted the bevel to be slightly rounded; we may never know for sure. Carvers commonly round the bevels of their chisels slightly in order to provide more control in the cut. I've tried it and can see the benefit.

I do think the whole NASA flat back and bevel thing has more merit to make future sharpening easier/more repeatable for honing guides. I don't see a big benefit in terms of using the tool to having a back or bevel that is perfectly flat for its entire length. The only area that really matters is the very edge where the back and bevel meet.

[Rick Prosser]

So, if I understand correctly - the convex area is the material beyond the "cutting edge" of the blade. (cutting edge is red in my picture) The cutting edge is very small - just the junction of the two sides of the blade.

Sharpen.JPG
(angles are exaggerated)

With the flat, microbevel, and convex shape, the cutting edge (red) is the same, but the remaining material (green) is shaped differently. I guess the remaining material gives strength and some chip breaking aspect to the tool, but should not impact the sharpness?

If true, then the method of shaping can just be your preference - ease of use, etc...

Maybe I am missing some other aspect of the debate?

[Andrew Gibson]

I finally broke down and hollow ground my chisels last week. They were all in bad need of regrinding, but because I had been using a honing guide I just never did it. ( was also scared of destroying my chisles on the be nch grinder)
I proceeded to free hand my chisels (only did half of them so far... the ones I use most) and was excited to get very nice clean paring cuts in pine.

There is something very freeing about picking up a chisel and in a minute or 2 having a nicely sharp chisel. It makes me much more inclined to walk over and touch up the edge when I dont have to fuss with a jig or guide... maybe that's why I have been using more and more hand tools.

Not sure how good I would be at this method, I like being able to lock into a constant angle and keep it there. It also would seem to me that you would have to remove a lot more material with the stone. with a hollow grind the wheel removes most of the material and all you end up honing are 2 very small sections of the bevel... The cutting edge and the very back edge of the bevel. A few strokes and your done.

[Jim Koepke]

Originally Posted by Andrew Gibson

I finally broke down and hollow ground my chisels last week. They were all in bad need of regrinding, but because I had been using a honing guide I just never did it. ( was also scared of destroying my chisles on the be nch grinder)
I proceeded to free hand my chisels (only did half of them so far... the ones I use most) and was excited to get very nice clean paring cuts in pine.

There is something very freeing about picking up a chisel and in a minute or 2 having a nicely sharp chisel. It makes me much more inclined to walk over and touch up the edge when I dont have to fuss with a jig or guide... maybe that's why I have been using more and more hand tools.

Not sure how good I would be at this method, I like being able to lock into a constant angle and keep it there. It also would seem to me that you would have to remove a lot more material with the stone. with a hollow grind the wheel removes most of the material and all you end up honing are 2 very small sections of the bevel... The cutting edge and the very back edge of the bevel. A few strokes and your done.

So many ways to sharpen… So little time…

There are as many ways to sharpen a blade as there are to skin a cat once the blade is sharp.

Without even knowing about it or what it was called some of my blades have acquired the Gimsdale edge. Did someone mention an endless series of micro bevels so small that we can not determine their seperation?

I like what Andrew says about the hollow ground blade. If one has the equipment and skill to do this, the touch up on the stones afterward is the easiest. The blade "clicks" into place and very little work is needed to get to a perfect edge. Of course, each time the blade is "touched up." the area being worked grows just a little.

I guess it gets down to if it works, that is all that matters. If it doesn't work, then keep trying something else until you can get your edges to cut the way you want them to cut.

jim

[David Weaver]

Originally Posted by Robert Rozaieski

I do think the whole NASA flat back and bevel thing has more merit to make future sharpening easier/more repeatable for honing guides. I don't see a big benefit in terms of using the tool to having a back or bevel that is perfectly flat for its entire length. The only area that really matters is the very edge where the back and bevel meet.

Roger that.

[Dale Sautter]

Originally Posted by Jim Koepke

So many ways to sharpen… So little time…

There are as many ways to sharpen a blade as there are to skin a cat once the blade is sharp.

Without even knowing about it or what it was called some of my blades have acquired the Gimsdale edge. Did someone mention an endless series of micro bevels so small that we can not determine their seperation?

I like what Andrew says about the hollow ground blade. If one has the equipment and skill to do this, the touch up on the stones afterward is the easiest. The blade "clicks" into place and very little work is needed to get to a perfect edge. Of course, each time the blade is "touched up." the area being worked grows just a little.

I guess it gets down to if it works, that is all that matters. If it doesn't work, then keep trying something else until you can get your edges to cut the way you want them to cut.

jim

Isn't that the truth Jim...

I'm really curious if using this technique might help prevent A2 edge chipping/brittleness on irons, say, for less than 30° like you might find/prefer in a low angle (20° - 25°) application. Forming a convex bevel is very easy on a belt grinder using a slack area or platen. Curious...

[Chris Friesen]

Originally Posted by Dale Sautter

I'm really curious if using this technique might help prevent A2 edge chipping/brittleness on irons, say, for less than 30°

I doubt it. Right up at the edge at the microscopic level where any chipping would occur the difference between a hollow-ground bevel, flat bevel, microbevel, or convex bevel is basically nil (assuming that the cutting angle is the same in all cases).

[Steve Branam]

Originally Posted by Rick Prosser

With the flat, microbevel, and convex shape, the cutting edge (red) is the same, but the remaining material (green) is shaped differently. I guess the remaining material gives strength and some chip breaking aspect to the tool, but should not impact the sharpness?

If true, then the method of shaping can just be your preference - ease of use, etc...

Maybe I am missing some other aspect of the debate?

Exactly! It shouldn't make a difference. That's why I don't understand all the fuss over it. Same angle where it counts. This method of achieving it is quick and simple.

But I understand people are going to have different preferences based on how they learned and what they've used over the years. For me as a newbie still searching for a good method, this has a lot of appeal.

[Tom Scott]

Until I recently got a honing guide, every blade I had took on this shape to some lesser degree. It wasn't intentional or as pronounced, but it was there.
The guy I learned from said the angle should be 30 degrees +/- 5. Worked for me many years. The biggest benefit of the honing guide for me is being able to get a consistent straight (perpindicular) edge.