How To Make A Clock In The Home Machine Shop – Part 4 – Cutting The Wheels

Updated : Nov 10, 2019 in Articles

How To Make A Clock In The Home Machine Shop – Part 4 – Cutting The Wheels

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.


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