Flattening completely screwed up chisel backs

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Forum topic by jonah posted 02-11-2019 02:56 AM 509 views 0 times favorited 11 replies Add to Favorites Watch
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2006 posts in 3569 days

02-11-2019 02:56 AM

I picked up a set of compact butt chisels at a yard sale, and two of the four are in decent shape. The other two, unfortunately, look like someone took a grinder to both sides of the chisel, not just the bevel. They look awful.

I started by trying to flatten the back of the wider one. After getting nowhere with a coarse diamond stone (~300 grit), I got out some 80 grit sandpaper and tried to just work the last half inch of the back. I worked on it for a solid 15-20 minutes but the end of the back (maybe 1/8” there) is still not getting flat. The rest of the back I’m working on is very, very slowly coming along, but it’s excruciating. I tried using the “ruler trick” to just work the very end, but even that didn’t really help.

Is there some better way to fix an obviously completely messed up chisel? I was so frustrated earlier I almost got out my belt sander.

11 replies so far

View BlasterStumps's profile (online now)


1166 posts in 710 days

#1 posted 02-11-2019 03:03 AM

I actually use a disc sander. You have to be real attentive and not get the steel too hot. I grind for a couple seconds and cool in water, grind again, cool again and so on. It is a bunch faster on real rough chisels. Once I get it cleaned up that way, I go to the diamond stone then water stone, etc.

-- "I build for function first, looks second. Most times I never get around to looks." - Mike, western Colorado

View bandit571's profile


22208 posts in 2954 days

#2 posted 02-11-2019 03:07 AM

Bevel on both faces? Grind straight back until the bevel on the back is gone….dunking often….then grind a new bevel on the bevel side….and go from there.

-- A Planer? I'M the planer, this is what I use

View MrRon's profile


5364 posts in 3514 days

#3 posted 02-11-2019 03:37 AM

A chisel so badly butchered needs to be ground with a surface grinder (I bet you don’t have one). You might go back an inch or two and grind a new flat surface, but the flat will still form an angle (bevel) to the rest of the chisel. Unless it was a very expensive chisel, like a Japanese one, I wouldn’t bother with it. All the grinding and sanding will generate heat and will not restore it.

View Fred Hargis's profile

Fred Hargis

5308 posts in 2764 days

#4 posted 02-11-2019 11:38 AM

Sometimes, the patient dies. I’d cut my losses and give up on it.

-- Our village hasn't lost it's idiot, he was elected to congress.

View rwe2156's profile


3280 posts in 1751 days

#5 posted 02-11-2019 02:37 PM

I’m with Fred. Unless its a valuable or unique chisel, I’d spend my time in a better way…..

-- Everything is a prototype thats why its one of a kind!!

View Tony1212's profile


286 posts in 2005 days

#6 posted 02-11-2019 03:12 PM

I made a video about flattening plane iron backs using a belt sander. It will also work with chisels. The main tip is using those cell phone auto vent magnets to keep a good grip on the metal blade.

-- Tony, SW Chicago Suburbs

View jonah's profile


2006 posts in 3569 days

#7 posted 02-11-2019 03:55 PM

Appreciate the responses.

I don’t have a disc sander, actually. I do have the Ridgid oscillating belt/spindle sander, and I’d thought about using that, but have no reliable way to keep the chisel parallel and flat to the belt.

The chisels aren’t anything special, but I do like the size so I’m game to try once more to get them workable.

View SMP's profile


341 posts in 176 days

#8 posted 02-11-2019 07:42 PM

View BlasterStumps's profile (online now)


1166 posts in 710 days

#9 posted 02-11-2019 07:44 PM

I have three chisels that need attention on the backs. Sort of like what you are talking except the damage is from rust. My disc sander is actually a low rpm motor mounted vertical with a 6” disc on it that has interchangeable discs with different grits sand paper on them. Think something on the order of a worksharp but not nearly as nice. I am dreading the job but like you I want the chisels to be nice again because of their size. Best of luck with yours.

-- "I build for function first, looks second. Most times I never get around to looks." - Mike, western Colorado

View ed13's profile


30 posts in 821 days

#10 posted 02-13-2019 08:36 PM

I won’t buy used chisels any more. The failure rate has been too high and too many hours have been wasted. It’s just not worth it unless it is something special. So often, it seems the tool was abused leading to dubbing at the edge that was just horrific to fix. One or two have been keepers, like a couple of nice, long paring chisels. If you have the setup to flatten the backs by machine, that’s one thing, but if you’re trying to get started in hand tools, it’s not a great way to start.

View Lazyman's profile


2874 posts in 1658 days

#11 posted 02-13-2019 09:46 PM

Compact butt chisels aren’t going to give you much steel to work with. You’ve basically go to grind at 0 degrees (straight into the wheel or belt) until the bottom bevel is gone and you have a flat back. Then you can regrind the bevel on the front. Then you can start the sharpening process. If you think you’ll have enough steel left after basically grinding off the end, they it could be worth spending some time on; otherwise, add it to your scrap metal pile for when you need a small piece of carbon steel for another project.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

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