One day I intend to make a watch.
I’m still a long way off, but tonight I made a good step in the right direction :)
A large part of a timepiece is of course the wheels and pinions. I’ve been contemplating how to cut them without bankrupting myself buying the cutters.
The Sunderland gear planer uses a fairly simple cutter for racks, and generates the curves of the spur gears by coordinating the cutting and a rotation, so the gear blank rolls against the rack as though it already had th teeth.
I have several old engineering texts with some of the relevant details in:
Of course I don’t have a gear planer, and generally they are for much larger gears, but I can use the technique with a little bit of lateral thinking.
First make a rack form cutter, simple lathe work.
Then wack it into an indexer on the mill
And create some flutes for the cutting edges.
Then handily I have recently bought a kiln (for enamel) which I can use to Heat treat. So much easier than a blowtorch.
I decided to keep the tooth count smallish for my first gear - 30 teeth /12degrees each. That also means I can use the simple divider. To assist my little brain I wrote down all the teeth angles so I could tick them off as I go.
Then it’s a question of put on the right cut and index /cut / repeat...
Once the first pass is done I rotated the indexer by 6 degrees, moved the cutter by an equivalent linear amount and cut it again. This generates the tooth curves.
The end result is gear shaped:
And meshes with another 48dp gear nicely.
I got a beautiful pattern when parting the gear blank off the stub it was machined as part of.
There is more work to do, but I think the method will work without too much effort.
Dave