Gear cutters for clock wheels

[HuubParticipant @huub]

Jouke,

with following results: 4.30(3); 4.30(5); 4.30(7) and 4.30(5)mm.
Great to see results are improving. Turning within 0.01 mm on a hobby lathe is not only good but excellent.

To my opinion this result is more than good enough to proceed to the next operation
I agree, you have the base for a good gear cutter.

I am looking forward to see the finished gear cutter and the gear you made using this cutter.

Huub

Edited By Huub on 17/02/2022 21:46:05

[Jouke van der VeenParticipant @joukevanderveen72935]

Intention was to measure thickness of glue between cutter blank and alu chuck face.

After 1/2 hour in boiling water the glue remainings still did not release. Therefore I decided to peel it of with a sharp blade. It came off in tiny thin pieces and not in one part. Not to measure but also with the conclusion that the super glue layer between blank and face was now (much) thinner than in my first trial (.08 to .09mm). I am convinced that this improvement must have helped me in getting the parallelism reported above.

[Jouke van der VeenParticipant @joukevanderveen72935]

Good progress.

Tooth shape has been machined on the cutter blank.

First on side of the blank was shaped into its final cycloidal shape and then the other side.

First a pre-shape was made with a standard 0.4mm radius carbide insert with steps following the final contour of theradius. This radius was made with the “half ball” radius tool described at the start of this topic. On the first side it was done with 200 rpm and feeding the radius tool with the cross slide. This suffered from some vibration and resulted in visual roughness in the radius. Therefore, this shaping was repeated by cranking the chuck by hand (as John P proposed!), resulting in a much better surface. This radius procedure was repeated on the other side of the blank but now in 3 steps, to get a nominal tooth thickness of 1.57mm.

Final result was a tooth thickness varying between 1.56(7)and 1.58(1)mm (measured with micrometer), not bad I think.

Next steps will be cutting the 4 teeth of the gear cutter, pregrinding the front of these teeth and then to harden it. First I will do some exercise on the cutter with less accurate shape made earlier.

[HuubParticipant @huub]

Posted by Jouke van der Veen on 20/02/2022 19:32:57:

This suffered from some vibration and resulted in visual roughness in the radius.

When turning using form tools, the cutting edge is often large. This gives a heavy load on the tool (post), comparable when doing threading. Let the tool stick out as minimal as possible and keep the tool above the tool post. If the tool shatters, reduce the RPM. Some times also to shallow cuts can cause chatter.

If you use the "Tangential cutter" you need to let the tip stick out as minimal as possible.

I keep the stick out of my tools below 12 mm. Only when turning between centres, I need more stick out. Because then the load is quit small, it is not a problem.

Final result was a tooth thickness varying between 1.56(7)and 1.58(1)mm (measured with micrometer), not bad I think
This is more than adequate for cutting gears.

Next steps will be cutting the 4 teeth of the gear cutter,
If you want to polish the flank of the cutter, do it before cutting the teeth.

 

 

 

 

Edited By Huub on 20/02/2022 23:10:45

[Jouke van der VeenParticipant @joukevanderveen72935]

Huub,

i think you are right to do it in that order.

Which method would you follow to polish? There are people who make a wooden contra shape of the tooth and let the blank rotate through it while a polishing paste is applied.

I think you should avoid to round the corners of the tip of the tooth.

What is your advise?

Regards,

Jouke

[HuubParticipant @huub]

Youke,

Which method would you follow to polish
I use in this order:

• 400 grid sand paper, sanding by hand (this dust is killing for the lathe ways)
• steel wool (safe to use on the lathe)
• dremel and polish paste (this dust is killing for the lathe ways)

I think you should avoid to round the corners of the tip of the tooth.
It would make the teeth a bit stronger but I never do it.

The CNC turned cutters have an excellent finish and are good enough as is.
From the the milled cutters, i only remove the burs by scratching with my nails. The finish is not as good as the turned cutters, but good enough.

After hardening (I only harden for cutting aluminium and HPL, not for plastics, don't cut steel) I only give the flat cutting face a few strokes on a stone (800 grid I think)
I don't relieve the 25 mm long fly cutters after hardening. I want them as hard as possible. I do not quench in oil (anymore) but use water.

[Laurie WParticipant @lauriew39626]

Appreciating that I am rather late to this thread, and my apologies for slightly straying from the original post, but this may be of interest to someone…

There is a really excellent book that covers much of this and far more besides:-

"Wheel and Pinion Cutting in Horology" by J Malcolm Wild FBHI.

First published in 2001, second impression 2005.

ISBN 1 86126 245 0

It is a very good read as it also covers the historical side as well as the practical. The presentation is unusually clear and it is very well illustrated. Of most importance of course is the fact that the information conveyed is accurate and very practical, and the methods put forward are based on long experience and work as suggested. Whether you wish to make your own cutters of various types or to use the splendid Thornton ones this book is a very useful resource.

[Jouke van der VeenParticipant @joukevanderveen72935]

Hallo Lauri,

Yes, I am aware of this book but I do not have it and had never the opportunity to look into it.

I agree, it could be very helpful in choosing proper techniques for wheel and pinion cutting.

Regards,

Jouke

[Laurie WParticipant @lauriew39626]

Hallo Jouke,

Yes it is always nice to be able to have a good look at a book before deciding whether to purchase it.

If it helps at all I have found that the publishers Crowood Press do have copies, as do a number of English bookshops as found on abebooks.co.uk website. Perhaps of more use if you are in Holland is that Amazon also carry copies.

Good luck with your cutter making, I am sure your hard work will pay off.

Regards,

Laurie.

[Michael GilliganParticipant @michaelgilligan61133]

If you need a flavour of J.Malcolm Wild’s knowledge and skill, have a look at his website: **LINK**

http://www.j-m-w.co.uk

… and particularly this article [which is linked on that page] : **LINK**

http://www.j-m-w.co.uk/HJ%20Published%20ArticleNEW.pdf

MichaelG.

[HuubParticipant @huub]

Jouke,

I finally finished the video about gear making. I started a separate topic and I hope it will get you on the way.

Topic

Video

Regards, Huub

[Jouke van der VeenParticipant @joukevanderveen72935]

Huub,

Thank you! I will have a look.

As I said before: when days get longer and temerature higher I spend more time outside, meaning that progress on gear cutters significantly slows down.
But now we get some winter weather.

On top of that I just recovered from covid-19, also not helping to make much progress on projects.

Regards,

Jouke

[Jouke van der VeenParticipant @joukevanderveen72935]

Hallo Huub,

I watched your video.

I think it is very instructive and so complete. I have to watch it again to understand all the details.

One thing is quite clear to me. I will nether reach the level you present in your video although I understand your way of working.

In Duch we would say: “Dit gaat boven mijn pet”. But that is not the proper expression. It is above my level because of lack of practical capabilities and missing precise machinery.

I will watch your video again. Thank you very much.

Regards,

Jouke

[HuubParticipant @huub]

Posted by Jouke van der Veen on 31/03/2022 13:38:26:

It is above my level because of lack of practical capabilities and missing precise machinery.

Jouke,

You under estimate yourself. You have the tools and brains. Your skills will grow, that is a matter of time. I am curious how you see this next year or so.

Regards Huub

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