Making a mini-chisel

A long time ago, I wanted a chisel for cutting slots narrower than 1/8" (for small lock-tongue mortises, etc.). So I cobbled one up by grinding down an old chainsaw file. It worked well enough, & I even made a nicer handle for it sometime down the track, but I admit it was a bit of a rough diamond. Then Derek Cohen showed us the 1/8 chisel he'd made, which made my effort look right dowdy. In the true spirit of a tool tragic, I felt obliged to do better, & when I saw a piece of 3/32 HSS at the woodshow for a mere $10 or so, I thought I'd have another run at it.

The piece was quite large, & grinding it down was out of the question, so it had to be cut. I did that by clamping it between two bits of 3/16 steel & using a 1mm cutoff wheel. I was worried it might affect the hardening, & took it very carefully, but the steel didn't get very hot at all, even on the free side. I tested the exposed bit after cutting, & it remained much too hard to file, so no softening occurred.

I ended up with two roughly chisel-shaped pieces (Pic 1), & made two chisels- a mini mortise as intended, plus a small bevel edge (Pic 2). To shape the bevel I used a coarse diamond stone - took an hour or so to get it even & neat, but was much safer than trying to grind it. It's a pretty delicate looking thing, but I tested it by putting a fair amount of leverage on the narrow end & it stood up. However, I certainly wouldn't recommend bashing it into dry ironbark unless you wish to see it shatter... :o

The last pic compares the original roughie with the new BE. Much happier with the appearance now .... :U

Cheers

Nice one Ian! In fact, nicer than the one I made. Gad, now I'll have to make another! :U

Regards from Perth

Derek

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Originally Posted by derekcohen

...... In fact, nicer than the one I made. Gad, now I'll have to make another! :U

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I wouldn't say it was any better Derek - no need to start an arms race! I am pretty pleased with the way the little BE came up, though, so my thanks to you for giving me the idea. It isn't something I have a great need for, I have to admit, but what else was I to do with that scrap of HSS? :U

Both chisels are so small I was easily able to squeeze them in the drawers with their matching big brothers (or sisters?). And the best part of it all is that since sets of chisels only count as one tool, I don't have any more tools than I had last week. :D

Cheers,

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Originally Posted by IanW

And the best part of it all is that since sets of chisels only count as one tool, I don't have any more tools than I had last week. :D

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Nice chisels and a great justification. :)


Regards,

Denim

Hi Ian,

Nice job, I find those small chisels are often the trickiest to shape and sharpen, you probably didn't have to worry too much about over heating, HSS is generally fairly tolerant of over heating.

Just for interest's sake what is a "lock tongue mortise"?

EDIT: Never mind, I just twigged, it's the mortise for the tongue of a lock :) for some reason I was imagining a variant of a draw bored mortise and tenon.. being that size, I guess it's a jewellery box or small drawer.

Regards
Ray

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Originally Posted by RayG

Hi Ian,

Nice job, I find those small chisels are often the trickiest to shape and sharpen, you probably didn't have to worry too much about over heating, HSS is generally fairly tolerant of over heating.

Just for interest's sake what is a "lock tongue mortise"?

Regards
Ray

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Hi Ray, yes, I am assured by a much more metal-savvy friend that HSS can be cherry red & remain below the critical temperature. To be accurate, I was more worried about embrittling the steel, or causing cracking, than I was about softening it.

A lock-tongue mortise is just the hole wot the tongue of a drawer or door lock fits into. Little locks have tongues that are quite thin, down to 1/16" in really tiny locks, & ranging up to 1/8" or more thick on larger locks. You can get away with digging out a hole with say a 1/8" chisel, then covering it with a brass 'striker' plate with a slot of the right width. The idea is to keep the fit pretty close, so the door doesn't rattle, if the lock is the sole means of keeping the door closed (as it often is). Being a fuss-budget, I like to keep the mortise pretty close to the right size, too, hence the occasional need for some rather skinny chisels.

Cheers,
Edit: Woops, didn't see your edit. "Yes, you are correct on both counts" would have been the appropriate answer.... :U

2nd Edit: Yairs, you are also right about sharpening narrow chisels, I also find them the hardest, particularly as I freehand everything. Difficult to keep tha narrow bevel straight & even!