Best way to flatten the back of a chisel

[Rick Barton]

Wow, that's a lot of metal to remove just to get the back flat.


You might be better off, Peter, finding a better candidate.

[Peter Tremblay]

Wow, that's a lot of metal to remove just to get the back flat.


You might be better off, Peter, finding a better candidate.

You're right.

The one that needs that much removed I'll either grind it back or just use it for chopping tasks.

The rest of them don't need that much metal removed.  

Well see what I can come up with.

[Bruce Haugen]

You're right.

The one that needs that much removed I'll either grind it back or just use it for chopping tasks.

The rest of them don't need that much metal removed.  

Well see what I can come up with.

I flattened the back of a fairly unflat 2” chisel quite easily with 15 micron diamond paste on a cast iron substrate.  30 micron would be faster.

[Bibliophile 13]

I have a really wide chisel whose back was very out of flat. What I ended up doing is using a bench grinder to VERY CAREFULLY grind a slight hollow into the back, making it kind of like a Japanese chisel. (The back was so out of flat that the chisel was pretty useless as it was, so I wasn't risking much.) Just little light touches here and there until the back was hollow up to about 3/8" from the edge. If I'm lucky, it will be decades before I sharpen the chisel back that far.

And it worked. I was able to then flatten the back by working through a series of sandpaper grits on a patten. It still took a little while, but not nearly as long as it would have otherwise. Might be worth a shot for you.

[Peter Tremblay]

I have a really wide chisel whose back was very out of flat.  What I ended up doing is using a bench grinder to VERY CAREFULLY grind a slight hollow into the back, making it kind of like a Japanese chisel.  (The back was so out of flat that the chisel was pretty useless as it was, so I wasn't risking much.)  Just little light touches here and there until the back was hollow up to about 3/8" from the edge.  If I'm lucky, it will be decades before I sharpen the chisel back that far.  

And it worked.  I was able to then flatten the back by working through a series of sandpaper grits on a patten.  It still took a little while, but not nearly as long as it would have otherwise.  Might be worth a shot for you.

That's not a bad idea.

Thanks, Steve.

[Kansas City Fireslayer]

I did a nice old Witherby 3/4” firmer on a granite lapping plate with sandpaper. 220 is about as low as I like to go when doing the heavy work. It was a painfully slow process but the chisel is pretty much dead flat and I love using it. You only have to do it once but I will say I’d pick and choose the ones you decide to flatten wisely. I agree with others that say some chisels aren’t worth the time.

[bandit571]

Used the "side" of a lot of things....side of the grinder wheel.....side of the beltsander....on the stationary beltsander I have, it also has a 6" disc.....I come in from the edge and work my way in towards the center.  

Remember, you do not NEED to flatten  the entire back of a chisel..maybe only the first inch is all that is needed...and..NO, it doesn't take "hours of work" to do...10 minutes, tops.    Otherwise, you be "milking it".

After that is done, then treat the back like the bevel on the stones, strop...whatever.

[Danny in Houston]

This is a flat chisel!  Took me a while to get it this flat.  ha ha

[Bruce Haugen]

This is a flat chisel!  Took me a while to get it this flat.  ha ha

Eye see what you did there!

[Rick Barton]

That's not creepy, Danny, not creepy at all.