How To Make A Clock In The Home Machine Shop – Part 4, by Clickspring.
In this video I go through the setup for cutting clock wheels, and cut the teeth for the 3rd wheel of the John Wilding “Large Wheel Skeleton Clock” project..
This is basically a light milling operation, carried out on the lathe, using a cross-slide mounted vertical slide, a light duty milling spindle, and a Sherline motor/speed control.
I also introduce the latest acquisition for the shop – a Divisionmaster cnc indexer.
Be sure to use breathing protection whenever you are heating super glue.
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Other Videos to Watch:
How To Make A Clock Part 3 – Making The Washers and Screws
https://youtu.be/KXzyCM23WPI
How To Machine A Small Lathe Carrier
https://youtu.be/zB9XhqzBNJs
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Transcript:
00:24 As to why clockmakers call gears “wheels”, I haven’t really found a good answer, but if it has 20 or more teeth its called a wheel, and if it has less than 20, its called a pinion.
00:46 So lets get into it. Starting out with a sheet of 1/16″ engravers brass, I lightly marked the center, and then roughed out a blank. You’re going to see me use these super glue arbors a lot as I make this clock. They’re perfect for holding workpieces that need to be machined on the edges.
01:12 The face of the chuck can be trued up if needed, little glue is applied, and then the rough blank is held in place with the tailstock for a few minutes while it sets. Its sort of a modern version of the shellac wax chuck that watchmakers have traditionally used. I turned the blank to the correct outside diameter, and then drilled and bored the center hole.
02:16 I made an adaptor plate for a myford vertical slide to fit the cross-slide, and also a platform that’ll hold the motor and speed control. A spindle is mounted on the vertical slide, and then indicated to be square.
02:40 The cutter is mounted on an arbor, and locked into the spindle, and then its lined up on the center of the work. In this case I’m using a centering button to identify the wheel center. The belt is tensioned to be tight at the full depth of cut, and thats the cutting setup all ready to go.
03:11 For dividing, I have these classic dividing plates, but the 290 tooth “Great Wheel” is a problem.
03:28 I had to make a few bits and pieces to make it work for my setup, like this expanding mandrel for the rear of the lathe, as well as support brackets. But this stuff only needs to be made once, and then its good to go for the future. So this is how the dividing mechanism fits onto my lathe.
04:15 The first step is to establish the correct depth of cut, and to do this, I took repeated cuts on either side of a single tooth, slightly lowering the cutter after each pass.
04:59 At that point, the cutter is at the correct depth to form the teeth, the vertical slide is locked, and then all of the teeth are cut in one pass. After all of the setup, the actual cutting of the teeth is pretty straight forward. The wheel can be taken off with a bit of heat.
06:21 Here’s the arbor for the stop work wheels. These teeth are a little long, so I made this one thicker, and just machined it away along with the brass to keep the teeth well supported during the cutting; same goes for the escape wheel.
06:33 The center wheel arbor is fabricated from 2 parts, as is the arbor for the great wheel. Apart from size, its essentially same thing in each case. Some wheels require different profile cutters. The escape wheel for instance, and the ratchet.
07:03 large tooth pitch, so it required a custom cutter. I used this button tool to form the tooth profile, It also needed its own custom arbor to mount it into the spindle.
07:15 and here’s the finished cutter, hardened and tempered. Other than those differences, its all pretty much the same for each wheel.
References:
John Wilding workshop and clock construction books:
https://www.ritetimepublishing.com/
Bill Smith, Master Clockmaker:
(Super Glue Arbor)
https://www.wrsmithtelegraphkeys.com
Lester Caine – Divisionmaster
https://medw.co.uk/wiki/DivisionMaster
How To Make A Clock In The Home Machine Shop – Part 4, by Clickspring.