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I Forge Iron

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Hey guys,
I won't be a regular here I just came to ask a few questions, if that's rude I apologize. I just thought I would find a forum of experts and ask away.
I'm a carpenter by trade and woodworker by choice, and worked in a manufacturing field for many years before that.
My questions are regarding using old files to make wood chisels, I have a decent set of chisels now but am frustrated by how quickly they dull when used in very hard and dense wood.
I can scratch the chisel metal with the file so I now that the file metal is harder. And I know that if I heat the file thourghly and the cool the metal very slowly I can take the temper out of it and shape it as I want, I know to that I can then reheat the metal and quench it to make it hard agian. Now bearing in mind that these chisels would never be struck with a mallet but only pushed. Do I have to reheat and temper it to keep it from breaking?
If so to what temperature or color. Is there a temperature crayon available to help with this?
Most Chisels are made to a rockwell hardness of 59-61 or of a2 toolsteel or even 01 toolsteel I would like to be harder than all of these, is this possible doing what I have discribed.
Thank you so much for your time and advice Denis

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I am a woodworker/carpenter too. I think you are on the wrong track with your chisel upgrade plans. IME old files are too high in carbon to be ideal for chisels. I am not saying that they could not be made to serve nicely (maybe even excellently) but they tend to be overhard and brittle. Because the main shaft of the chisel is fairly massive it rarely breaks (even when the steel is overhard) instead the edge flakes off in small chips which make for a REALLY DULL edge! You'd have to compensate for the extra high carbon content by hardening less or tempering to a softer color. I have done it but you are fighting the steel's natural properties and doing non-standard things to overcome a poor choice of steel.

I'd really reccommend that you take a closer look at the chisels that you have. Are you sure that they are sharpened optimally:confused:. However well the edge is honed if the bevel is too long the edge will be too weak and the edge will bend or break under the stress of hardwood chiseling. If the bevel is too blunt the force required to pare with the chisel will be excessive. Do you polish the edges:confused:, because that helps with durability... otherwise the tiny teeth created during the sharpening process can fracture off creating a dull ragged edge. Also be aware of your technique in using the chisels. Hard scraping or prying with the chisel edge can be quite destructive of their finely honed cutting edges.

Assuming that you have thought through and tried various of these stratagems and are still convinced that your chisels are just too soft, then consider rehardening the tips of your existing chisels. I have done some good in this way just by torching the chisel edges until the thin metal there begins to glow and then quenching immediately. I take advantage of the ease with which the thin sections of the chisels heat up to zone harden the edges. If you do this carefully and try to keep to a dull red heat only at the thinned edge and then quench in oil... you should be able to get by with the one step (that is you can skip the process of drawing the temper). I have made some good tools out of some completely unusable ones this way. It may be worth a try on one of yours... then if you like it do the rest of them too. It saves a lot of time over forging them from salvage steel. The steel is rarely at fault. Most often the problem is operator abuse/misuse or poor hardening and tempering of the steel.

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bigfoot has some good advice, old old files are usually 105 points (1.05% carbon), while more modern files are 95 points.

If you really want to make some chisels out of old files, work to desired shape, then heat till the metal is nonmagnetic 1460 degrees, a magnet hanging from a dowel will not attract to the hot metal, quickly wire brush any scale and quench in used vegetable oil ( use caution and full arm and face protection) as the oil will flash (burn), clean off the oil residue and put in a kitchen oven at 400 degrees for at least 45 minutes and then remove and quench in water to temper.

Have you tried a 5 or 10 degree micro bevel on the very end (cutting edge) of your current chisels? I'm a galoot or neanderthal hobby wood worker (hand tooler).

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thanks for your replies guys,
The chisels are ground with the factory edges 25 or 35 degrees i'm not sure. i polish the back of the chisel using 600 sand paper and going finer in stages until i reach 2000 then i hone the back to 8000 grit water stone and the face the same next is a small micro bevel at about 2 degrees steeper last both sides are polished with a leather strop coated in jewellers rouge.shine like a mirror and razor sharp. I notice on the really hard woods the edge doesn,t break but tends to roll or deform slightly. I didn,t know that I could try to Harden the existing chisels, so i guess that will be my first step. Once agian thanks for taking the time to answer if anyone has anything to add i will be checking back regards Denis

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