Trying to learn about Clock Gears

Got to say I disagree with that! Maybe an an amateur clockmaker would never use CAD, but I'd bet money the likes of Phillipe Patek do! While it's possible to make excellent clocks using craft methods, why not take advantage of advanced tools if they're available?

Is it that Old Dogs don't like learning New Tricks? Michael's link to the views of Richard Thoen quotes 'A Treatise on Gear Wheels' (1890):

The cycloidal tooth would never be missed if it were dropped altogether. But it was first in the field, ...has the recommendation of many well-meaning teachers, and holds its position by means of "human inertia," or the natural reluctance of the average human mind to adopt a change, particularly a change for the better.

Bazyle's view is also at odds with more than one Horology Textbook. Grossman's much esteemed 'Lessons in Horology' (1905) can be downloaded from - shock horror - the internet! (My dad was convinced computers would never catch on!)

Chapter IV describes various ways of deriving gear profiles, for example graphically:

Plenty of value in employing craft methods as a hobby, but primitive skills and copying others is only the beginning....

Dave

There are those that talk about it and those that do it.

CAD:

CAM:

CNC:

Real gears:

I thought that the involute tooth form gave primarily a rolling contact, with a little sliding. It would seem strange to use a tooth form for power transmission that has inherent losses due to friction over another tooth form.

Andrew

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Well said, Dave

MichaelG.

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P.S. This page of links might be of interest to some, over the ‘festive’ season: 

https://mb.nawcc.org/threads/digitized-books-related-to-watches-and-watchmaking.53214/

... although I share his concern about some of Google’s scans.

Edited By Michael Gilligan on 23/12/2019 10:53:31

Thanks for all replies has helped a lot and from my research to date Bazyle's post here is where I currently am at.

What I am still confused over is what is meant by 'rack' in relation to tooth / gear machining. If it is a line if profiles I don't get it ...can any clarify what a rack is in the context of making a wheel or pinion?

Chris

What I am still confused over is what is meant by 'rack' in relation to tooth / gear machining.

A rack is a gear of infinite diameter.

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Chris,

Yes a rack is, as you surmise, a line of profiles ... as in a rack & pinion mechanism.

This is the primary form, from which specific wheels and pinions can be generated by shaping.

Risking the contempt of Hopper : I’m afraid you will need to do quite a lot of background reading, if [as it appears] you want to understand the subject.

MichaelG.

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Edit: Start here to get an idea of the basics: https://youtu.be/J1UOjBLo-2

Edited By Michael Gilligan on 23/12/2019 11:36:39

Thanks Michael. The issue is I have collected numerous facts and opinions on this subject and realised I needed time to get an understanding. I hope this is now coming together. over the next few months my project will be to machine a brass wheel so a certain amount of knowledge is required.

i suspect as I try to start actually doing it the issues and lack of understanding will initially jump out but that's the fun of achieving new horizons.

Chris

As an aside I note there is no obvious 'Edit' facility on this forum which seems a pity...am I missing a trick here?

chris

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The edit option is only available for a short time, unfortunately

[ look for the ‘edit post’ button in the green bar at the top of your post ]

... You will see that I just had time to edit my post.

MichaelG.

Edited By Michael Gilligan on 23/12/2019 11:34:47

Eloquently put. If I ever finish my traction engines I fancy making a clock, and darn right I'd be using CAD, CAM and CNC as well as hand methods.

Andrew

Edit is available for long enough to allow correction of 'oops' errors but not long enough for the retrospective edits to win arguments seen on some less well mannered forums than this one...

Neil