G'day Chris here, and welcome back to Clickspring
In this video, I go through the steps for cutting the wheels.
Despite the range of sizes for the wheels on this clock, for the most part they're made
in essentially the same way.
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.
Rather than show the cutting of all the wheels for this clock, which I thought might be a bit tedious,
I'm going to cover the process for this 144 tooth wheel as a representation of all of them,
and then later in the video, I'll show the differences for the others.
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.
The face of the chuck can be trued up if needed, a 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.
So I need to be able to divide the work, and also make the cuts to form the teeth.
There are probably as many ways to do this, as there are lathes, but this is how I do it.
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.
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.
For dividing, I have these classic dividing plates, but the 290 tooth "Great Wheel" is a problem.
I don't have a dividing plate to cover that tooth count, and I guess I could have made one,
but it was just the excuse I've been waiting for, to invest in a new toy - a digital indexer.
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.
Now I know I'm really spoiled with this, but it really simplifies the job of indexing the lathe.
I can move forwards or backwards without having to think too hard,
and best of all, I can now get any tooth count I want.
Ok so after all of that setup, lets finally cut some teeth.
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.
The idea is to keep increasing the depth of cut until there is just a whisper of blue remaining.
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.
And each wheel is essentially cut the same way, although there are a few slight differences
in each case.
Firstly, the super glue arbors. There is no arbor required for the brass pinions;
I cut those from rod stock, so they're easy.
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.
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.
And there are no commercial cutters available to make the stop work wheels - it has a rather
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.
and here's the finished cutter, hardened and tempered.
Other than those differences, its all pretty much the same for each wheel.
In the next video, I'll tackle the 2 hardened steel pinions.
Thanks for watching, I'll see you later.
And if you're new to Clickspring, welcome. I post regular video's on machining and clockmaking.
So if home machining is your thing, hit that subscribe button, and I'll see you on the next video.