No-name eBay chisel restore

Scott H

Scott
User
I got a fairly inexpensive socket chisel on eBay to see if I could restore it to working order. It is 1.5" wide. No maker's mark, pretty big grinder gouges on the top (ownership marks?) and some cracks in the steel visible on the back near where the socket starts. The back was not especially flat initially and that took the most time to address. I did get the whole back flat, although I didn't polish the whole thing.

One interesting thing is that it has leather washers on the end of the handle (some are missing now) but also it has its neck cranked slightly like a slick, so the socket and handle just clear the plane of the chisel bottom. I might still try to replace the leather washers for appearance's sake but I doubt I will be hammering on it due to the cracks. I don't know what purpose a chisel with both the slightly cranked handle and leather washers has, but I am not really an expert in chisel variations either.

I got the back flattened, edge squared off and bevel re-ground on the grinder, and then sharpened it up. Unfortunately the edge seems to fail much more quickly towards one corner of the blade than the other, especially on end grain. I can get it so the whole blade shaves arm hair, but in use the right 1/3 or so of the blade easily gets chips and nicks similar to when you have too low of a bevel angle. I'm still trying to figure out if that's my fault and if I can fix it. The back doesn't seem less polished on that side and I don't think I overheated it on the grinder but I guess it is possible I let it get away from me without noticing. I tried rubbing a needle file on the middle of the bevel and neither side seemed terribly different.

All in all it may not end up being a reliable user with the cracks and whatever is going on with the uneven wearing but I think I learned a lot.

Some of the photos of the back and bevel before:
s-l1600 (1).jpgs-l1600.jpg

After:
IMG-9313.jpg IMG-9312.jpg IMG-9307.jpg IMG-9308.jpg
 

Chris C

Chris
Senior User
I didn't see the cracks but I'd sharpen it up and use it regardless. That's a nice piece of steel.... should make a nice user.
 

Scott H

Scott
User
@Chris C Thanks! The cracks are very subtle, I might take a picture of them up close. I do wonder how they got there.

I'm hoping I can figure out why part of the edge has poor edge retention. The rest of the edge seems great. I am thinking about grinding it back another bit and just hoping it's just that I overheated a sliver of metal on the very edge this morning. Hoping it's not just got inconsistent temper or something.

Edit: Probably going to give polishing the back another go as well too, maybe before that. It looks like it should be okay but maybe there are scratches weakening the edge or something.
 
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Scott H

Scott
User
Unfortunately it looks like you are right @Oka. I ended up taking a file to the edge and the side that kept failing is way too soft, and it doesn't seem to be shallow. The file skates off the left half of the edge but towards the right I can file it very easily. I am doubtful that I could have done that myself without seeing any discoloration on the back while grinding. I tried various other parts of the chisel and while I am not an expert in checking for hardness with a file it seems like it bites more than it should at a lot of places.

I think the lesson I learned here is to take a file to the chisel before spending time restoring it if you want it to be usable.
 

Oka

Casey
Corporate Member
Turn it into a Skew Chisel. Cut it at and angle and reshape it. Then, you get rid of the soft part and the chisel has a new use.

When you cut it go slow and cool with water. If you use a cordless grinder to make the primary cut you can run water over it just behind the cutting area to keep the temperature down. Pretty easy. If you go that route, look for an .020 width cutting disc. They wear out faster than the .040 but are way better for detail control work.
You can use a produce bag or one of those small plastic bags taped to the body to protect the motor part of the grinder from the splash.
 

Scott H

Scott
User
@Oka I will keep that advice in mind for the future, unfortunately I don't have an angle grinder right now. It seems like maybe it does get a bit harder back from the edge on the right, and then gets softer again towards the handle. But it might be still like a good quarter inch of metal back from the current edge which is more than I care to grind right now. I am not that experienced with file testing hardness though so I am not super confident in that assessment, I am 100% sure it is soft near the handle and on that top right corner of the edge though.
 

Oka

Casey
Corporate Member
File testing is not hard. Just get a small triangle file like a one that sharpens a dovetail saw (1/4") and use your hands to "feel" the resistance on the good side then up 1.5-2"from the cutting edge, use that as your register reference and work your way down 1/4 " at a time on the bad side until you fell the change. Always applying light pressure and keeping it consistent as you test. Really just a feel thing.
 

Scott H

Scott
User
I tried it with a fresh saw file. It does give more feedback but I really can't feel a point on the bad side where it gets harder, it just stays the same and gets softer near the handle. At this point it is just so cosmetically poor from file marks and the edge would require so much grinding to restore from test filing that I do not really have any interest in working on it further right now.
 

Hmerkle

Hank
Corporate Member
Scott - likely you are seeing the hardness at the edge of welded hardened steel, and as you get closer to the handle - that is mild steel - remember these are forged chisels, so rather than make the entire thing out of "good" steel, a good portion was welded onto mild steel that had the socket formed in it...

oh, and yes, this is likely a "framing-type" chisel where you don't want the socket to "stop" you from a paring cut - so the socket is "cranked" slightly...
 

Scott H

Scott
User
Scott - likely you are seeing the hardness at the edge of welded hardened steel, and as you get closer to the handle - that is mild steel - remember these are forged chisels, so rather than make the entire thing out of "good" steel, a good portion was welded onto mild steel that had the socket formed in it...
Thanks, that might explain some things. I managed to find a Woodwright's Shop video showing a chisel being hand forged and watched that too.

I can't see any visual indication that there are layers or a weld on this -- I have no idea if you would be able to -- but the only thing that makes sense from the file testing I did is that it was originally hard near the cutting edge and not elsewhere, and over time the good steel has been ground away and is feathering away to being too soft to hold up well. I don't know whether the good steel was different because of alloy or because of heat treating, but that is the sense I am getting.

Maybe down the line I might try heat treating it and see if it gets better. I don't have much of the equipment for that right now but maybe someday.
 
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Scott H

Scott
User
Maybe I missed it ..... What angle did you grind?
Primary was ground 20 degrees, which was more or less how it arrived. I started with a secondary bevel of 25 degrees, then tried 30 when I saw the edge was failing so easily on the right. I kept re-sharpening the 30 degree secondary thinking maybe my sharpening was to blame, didn't help much. Then when I realized it was the steel and not my sharpening I stopped trying to make a larger secondary bevel. Maybe a higher angle would have helped it stand up longer but once I touched that metal with a file it was clear it was way way too soft.

you could try re-tempering it if you have a MAPP gas torch.
Don't have a torch right now but it's on my long term list of stuff to try!
 

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