Originally Posted by
Pat Barry
I am having difficulty understanding the comments made about the back of the chisel not needing to be flat. Here is why. It is my understanding that the back of a chisel is the reference surface and is flat to provide a contact surface to guide the tool along a straight pathway thru the wood. Now I understand that certain chisels may have concave surface on the back, but that portion of the tool is incidental in that design. The bearing / reference surfaces are the non-concave portions, particularly the edges, and those are ground and polished as flat as possible. Pits and so on have no bearing (sic) on the performance of the flat back. On the other hand, the back of the chisel can't be convex or raised with respect to the bearing surface. If it is bumped up then it better be flattened or the tool will not function as intended. Being concerned with flatness is therefore important for traditional, er European, chisels.
To my knowledge, tools won't go straight through wood. Since you have a wedge, the bevel part of the wedge pushes the tip of the wedge back. I actually have rarely ever gotten anything wedge-shaped to go straight through anything.
With that being said, I don't use the backs of my chisels for reference. If there's one thing I've learned quickly, it was that wood is not the same density and it's way too easy to have a corner of a chisel dive into a softer portion of the wood and screw up what you're doing. If I want to check flat, I find a straightedge.
And to be completely honest, I want to work wood, not metal. Wasting time flattening a tool that's getting ready to cut into an organic medium that will change, to me, is just completely absurd. You'll never get wood flat and keep it there. . .why waste time getting your tool flat so you can get frustrated that your wood isn't flat?
Now, that being said, I don't use tools that are obviously out-of-flat by a mile, but if I see a little light on a chisel, I'm not going to let the OCD go nut-nut and lap it flat. Same with the wood that I work. Do I look for dead-perfect flat? No, I don't have that much time in my life. But if it's an obvious 45* slant, I might take it down to 15*.
The Barefoot Woodworker.
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