Thread: How to make a 3mm mortice chisel ?

Use a belt sander on each side. Obviously, you just need to remove a little (0.5mm).

I've done this to make custom sized mortice chisels. This one was between 1/8" and 1/4", and fitted into the groove left by a LN #49. I preferred a slight trapezoid shape for easier release ..



Regards from Perth

Derek

sander or grinder. If you're confident that you could reharden it accurately, you could draw the temper out of it and file it (which would probably be easier for tidy work).

I would only trouble myself to narrow an amount that would go in the mortise, and have several old junk chisels that have been done that way (wider chisel where only the last one to three inches has been modified narrower). The benefit of that beyond time savings is that the chisel itself will be stronger.

If you have access to an engineering workshop the blades from adjustable reamers make great little chisels.
H.

Here's the pattern if you want to make it from scratch instead of modifying another tool. Find the instructions here and a downloadable PDF with a better pattern. Then all you need is a piece of 3mm o1 tool steel and the ability to heat treat and temper. A little mapp torch or similar would do. https://mcglynnonmaking.com/tag/plane-floats/ Make yourself a couple of plane floats while you are there.

Not meaning to one-up you Doug, but actually, there's an even easier way, if going from scratch. Use a 3mm square HSS rod. I built a forumite a dovetail chisel using this, and the advantage here is that no heat treating is necessary. The HSS takes an excellent edge. In the case of a mortice chisel, it should have good impact resistance.



Regards from Perth

Derek

Originally Posted by derekcohen

Not meaning to one-up you Doug, but actually, there's an even easier way, if going from scratch. Use a 3mm square HSS rod. I built a forumite a dovetail chisel using this, and the advantage here is that no heat treating is necessary. The HSS takes an excellent edge. In the case of a mortice chisel, it should have good impact resistance.

That's ok Derek, I certainly do not feel that I have been one-upped at all. Horses for courses, as usual.

3mm square HSS might be fine for fine dovetailing, as yours was made to do, but you would have to be careful how much leverage you use on that if you were mortising out 3mm x 15mm x 50mm deep. It could become a longer and more tedious job than it needs to be.

But seeing as Dengue wants to use his for string inlay then either way would work I suppose, so it is good that we both provided our input.

I wanted a very fine mortise chisel (for tiny lock-tongues, etc.) and was a bit nervous about the brittleness of HSS, so I made sure mine had plenty of depth in the blade: Narrow mortise chisel.jpg No problems so far..

For cleaning inlay grooves, I imagine a wider blade would be better, anyway, as it would help to register it in the channel you're cleaning out.

Out of interest, I tried snapping a scrap of the HSS I used on the mortise chisel and found it to be tougher than I expected, so later, I made a couple of much finer BE chisels (3/32 & 1/16"): Mini D-T2.jpg Again, no problems so far, though I certainly don't use them to lever out chunks of Ironbark!

Apart from ready availability in a range of sizes, one of the big pluses for HSS is that you have to be very brutal to alter the temper (that's what the 'high-speed' part is all about, of course!). It will certainly blue if you push it, but most high speed steels can get to cherry-red without affecting hardness. So you can lay into it with a cutoff wheel & grind it with relative impunity.

Cheers,

Thanks for your help and suggestions everyone. In the end, not having a belt sander, I tried flattening it on coarse W&D paper, wthout making much impact, more of a polishing effect.

Tried rubbing the chisel along a flat file fixed in a machinist vice, same effect.

So then put it on the side of a grinding wheel, went OK, but I did blue it when I went for too long without dipping it in water.

End result is still a quite sharp chisel which works well. Only drawback is the chisel is tapered, so it is only 3mm wide for the first 20mm, which is not a problem for the application