Is this chisel defective or abused?

[Harlan Barnhart]

I was happy to find this 1/4" Swan mortise chisel full length for $10. Until I used it in white oak. I admit to doing a little prying but I wasn't expecting this. Has this chisel survived because the previous owner knew something was wrong with it, or am I too much of a man?

Second question, is it repairable?

I wish the second picture were clearer, but the last 1 1/4" has a nice hook. If a straight edge were laid on the back, there would be a 1/4" in gap.

[David Gendron]

Holy ... How deep in the mortise was the chisel when prying on it? I would try to bring it back and retemper it, it might work.
Good luck

[Jim Koepke]

My opinion could be wrong, but it seems a mortise chisel should break from abuse before it bends. It may have not been tempered properly.

jim

[David Weaver]

It's not hard enough, for one of two reasons:
1) someone thought they'd temper it and over did it
2) the steel is bum, not enough carbon

I'd hammer it back, reflatten the back while it's still soft, and then if you have the means, heat it until you see carbon starting to migrate on it (it'll look like bubbles on the surface) and quench it in oil. Run a file across it after that to see if the file skids. If it doesn't, use it to dig out weeds.

If all of that sounds like too much work or confusing (or if you don't have the means to heat the thing - most probably don't), I'd discard it and get another chisel.

[James Taglienti]

Are you sure someone didn't grind the bevel on the wrong side? It looks like the hardened steel is on the short side of the bevel... i know a lot of mortise chisels have a hook to them, and it curves kinda like that.

[Graham Hughes (CA)]

That steel is not hardened right. Probably somebody tried burning the previous handle out or something. If it's a Swan the steel should be hardenable; David's instructions should rectify the problem.

[Rob Fisher]

...then if you have the means, heat it until you see carbon starting to migrate on it...

What is the best way to heat a chisel for this purpose? Mapp gas? Propane? Coal forge?

Rob

[David DeCristoforo]

"What is the best way to heat a chisel for this purpose?"

A charcoal forge will provide the best quality heat. Heat from gas, regardless of the kind of gas is inferior heat. Electric heat is the most useless of all. OK... yes, I'm yanking your chain. It doesn't matter a whit... heat is heat. But I sure wish this was April 1st!

[Wayne Hendrix]

"What is the best way to heat a chisel for this purpose?"

A charcoal forge will provide the best quality heat. Heat from gas, regardless of the kind of gas is inferior heat. Electric heat is the most useless of all. OK... yes, I'm yanking your chain. It doesn't matter a whit... heat is heat. But I sure wish this was April 1st!

Might as well have been I totally believed you until you said otherwise.

[Shawn Albe]

or just leave it as is and use it as a "swan neck" chisel to clean out the bottom of deep mortises.

[Stephen Shepherd]

If it is a laid steel blade [thin veneer of steel on wrought iron] then the wrought iron has bent as has the steel. Easy to repair if you heat it up to blood red heat then quench in water or brine. Then 'let it down' by tempering to the proper color.

Stephen

[David Weaver]

What is the best way to heat a chisel for this purpose? Mapp gas? Propane? Coal forge?

Rob

Like david says, any heat, but a large uniform heat pattern. Probably 1 in 200 people on here have a setup that could do the chisel properly up to the socket.

I have the setup that Larry Williams shows in his video, but with a little more torch and I'd say it's still probably not enough.

I would toss the chisel or save it for something later. You'd almost need a charcoal forge to do a chisel of that size without doing the socket.

I've had ok luck with a mapp torch for very small plane blades like shoulder plane blades and chisels up to about an inch. Larger than that, and there isn't enough heat source to get the job done.

Larry Williams' moulding plane video has the best video work i've seen of heat treating something - it's really clear. You can't really watch that and screw anything up with O-1 or similar oil-hardening steel.

[Mark Kosmowski]

Chop a through mortise down the length of a refractory brick and then chop a mortise in the middle of a face that goes into the first mortise. Now you have an oven suitable for small things like your chisel. Apply a torch (propane, MAPP, whatever) to the 2nd mortise (acting as a port).

Be gentle doing all this and you might want to chicken wire up the brick before you start as they're fragile.

Or just support your local blacksmith at the end of his workday with a six pack of his favorite adult beverage.

[george wilson]

Like I said before,I've rehardened several good name(like Witherby) antique chisels for guys who bought some of their own tools to use in Williamsburg.

It is possible that the chisel went through a house fire and got annealed. It should have snapped off if you pried too hard.

It may very well warp if you reharden it. Most of those are tapered thinner at the back,and yours is beveled at the cutting edge,too. I advise hardening only the last inch for that reason. You'll never use an inch up,probably. More could be hardened in the future if you do.

Best straighten the chisel while the bent area is red hot. See below:

The easiest thing to do is fill a gallon can with water from the faucet. Lay 3 bricks down so you make a corner to lay the cutting end of the chisel in. Heat the first inch with a Mapp gas torch. 1 torch should do it,but sometimes I use 2. Heat to an orange color. Dip vertically into the water as deep as you can. Polish off the surface to expose bare steel,and slowly heat the chisel BEHIND the cutting end(on the end the socket is on. Let a medium brown color develop. Keep taking the torch away,letting the color creep to the tip. Be careful,the tip can overheat real quick. If you start to get purple color,quickly quench,polish off again,and re start the process,being more careful. You won't hurt the tool doing a repeat tempering. What will hurt is if you go to blue. In that event,you have to reharden the tool,and re temper all over again.

[Harlan Barnhart]

Thanks for the all the advise. I'm still not sure what I will do with it. My cousin has an acetylene torch with a "rosebud" heating tip. I might try to heat it with that. Now it makes more sense why a nice old chisel would be so long. One detail still doesn't make sense, the edge retention wasn't that bad. It was still pretty sharp when it bent (on the sixth mortise). If it lacks proper hardening, why does it keep an edge?