Gear cutting

[HevansccParticipant @hevanscc]

I decided to make a radius turning tool by adapting a boring head, as per Instructions of one of the forum threads. So started a proverbial 'there's a hole in my bucket dear Liza' project …

I needed to thread an arbor for the borimg head but it was too big to do easily with a die, so obviously a job for screwcutting on the lathe. Trouble is I don't have all the changewheels necessary . . . Easiest solution is to buy them, but this turns out to be pretty pricey. Next option is to cut my own, but the 20 PA 18 DP cutters necessary for the job are equally pricey – yes I know there are cheap cutters available but they are all 14.5 PA.

Having got to the this impasse, largely a consequence of not wanting to part with too much of the folding stuff, I decided to make my own cutters after the method of Ivan Law in his useful book, but using the technique described by Mikesworkshop using cone drills. Luckily, I have access to a muffle furnace for hardening and tempering, and the whole process seemed to go smoothly, with the usual mistakes and curses.

I cut the gears from delrin, which the cutters had no trouble with, and I must say I am pleased with the results considering I have never done anything like that before. I have not used the gears in anger yet but they seem to mesh OK.

So, having rambled on for a bit, the point of the post is to encourage any other novice engineer to give it a go . . .

Hywel

[HevansccParticipant @hevanscc]

[Nick HulmeParticipant @nickhulme30114]

Looks good, what's your lathe?

[HopperParticipant @hopper]

Nice work. What material did you make the cutters from? Silver steel or gauge plate?

[Thor 🇳🇴Participant @thor]

Nice work Hywel, I have made gears from Delrin, they work well.

Thor

[HevansccParticipant @hevanscc]

I have a metric Viceroy lathe. The cutters were made from gauge plate, 10 x 3 mm, which I hardened at 790 then quenched in rapeseed oil. Tempered at 200 for 1h.
Hywel

[Michael Cox 1Participant @michaelcox1]

Very nice job. I am pleased to hear that others are using the cone drill method. It is so much easier than the button method.

Mike

[HevansccParticipant @hevanscc]

The cone drill method is very elegant. The sizing rings are essential though. Also, as others have noted,the spacing and indeed calculations vary depending on who’s you use. However, given that they are all only approximations to an involute curve the differences turn out to be negligible I imagine. Maybe there should be a sticky thread on this (someone will now post to say there is and I have missed it . . .)
Hywel

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