Had a bit of painting to do and change a light bulb-
I want to make a stepper chuck drive to make some large threaded parts.
Please note- I pre drilled the head stock casting when I had it apart- I have photos of that experience if you want to see it?
The project is a plate to mount the stepper (from the bridge lifting drive), a belt and a big pulley to go around the chuck.
The problem is I can’t find a cheap pulley wheel for this- and it will require lots of machining even if I do. So taking inspiration from CNC Zone I decided to cast one of my own.
I’m jumping ahead.
The pulley design has to be in several parts so that it can use the chuck mounting bolts.
The funny shape backing plate is designed to fit over the chuck mount plate and use the same mounting points as the chuck. The steel ring that forms the inside hub of the pulley is held to the back plate by six screws. The hub fits snugly over the chuck mount plate to keep the assembly concentric. The black pulley wheel shown above will actually be made of resin and cast over the hub to form a single part.
So first the backing plate- and even before I start machining I made card version to make sure it would slip over the chuck backplate.
So now a piece of ali on the mill and the backing plate is cut out.
Phew it fits.
Now for the pulley hub.
A steel plate, and a bottom machining end mill- and lots of holes.
I cut it from the steel plate and mounted it in the lathe and cut the outside to diameter, then with the external jaws fitted I cut the inside diameter. I put 3 shallow valleys on the outside diameter to increase the surface area for the pulley resin, but the inside diameter was the most tricky to machine- first it has to be accurate and second the part is distorted by the chuck. I crept up to the final diameter 0.001” at a time till I had the perfect push fit.
I now have to make a mould for the pulley teeth. I’m going to copy the filled epoxy resin idea cast inside a poly belt. The only change I’m making is to use a different style of mould.