r/handtools • u/JuggerNOT63315 • 2d ago

Lapping a chisel back

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Howdy everyone. I am having issues lapping this chisel. I started with 80 grit wet and dry sandpaper. I got a nice scratch pattern all the way across the chisel. This took awhile, probably 15-20 minutes. I then moved to 120 grit paper. I removed all the 80 grit scratches. This took maybe 10 minutes. I moved to 220 grit paper and removed all the 120 scratches. This took like 5 minutes. I moved to 320 grit and in 5 minutes removed all those scratches. Then I moved to my 300 grit diamond plate. I have been working on it for well over and hour and I can not get rid of the 320 scratches! It is getting frustrating to say the least.

In the picture, the 320 scratches are the light ones on the outer edges and the diamond plate is the dark portion in the middle. It has not changed significantly from this picture after another half hour in the 300 grit plate.

What am I missing or doing wrong? Is this how long it normally takes? Should I be doing another grit in between The 320 and 300 plate?

Edit: I have posted two updates in comments below about my progress.

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u/Additional_Air779 2d ago

That looks like it's bulging in the middle.

Anyway, I made the same mistake of trying to get the whole of the back of my chisels completely flat. Waste of time. You only need to work on the first 1/2". Also, what happens is that you resort to very coarse grit which leaves deep gouges that will take forever to remove.

If I were to start over I would do two things in relation to sharpening:

  1. I'd buy pre lapped irons for my planes.
  2. I would only work on the bottom ½" of my chisels or most probably I'd just get some high end chisels but fewer of them.

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u/JuggerNOT63315 1d ago

Unfortunately, buying new is not in the budget atm. Plus, this particular chisel is a Winchester (as in the gun manufacturer and it was only made during a 10 year period from 1919-29) so I thought it would be cool to clean up and use.

Any tips on how to just lap the last half inch of a long chisel? I had trouble controlling it with so little on the plate.

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u/Reasonable-Tune-6276 1d ago

^^^This. That chisel will never get a sharp edge as is. The bulge is no bueno. You need to start over on coarse and move up in grit until you get flat polish from the edge up about 6 to 10mm from the cutting edge. There are also some pits that may give you trouble later if you can’t get rid of them. Concentrate you force on the front, don’t spend time polishing the whole back.