Welcome to our article abut how we built our homemade cabochon machine, in all it cost about £250.00 including wheels, motor and shaft and everything else that went into it.
Here is a picture of the complete machine as you can see it’s relatively compact, none too pretty but it does the job.
The whole thing is made of marine ply, we used a 4’ x 2’ x ½” sheet.
First we cut a 2’ x 2’ piece to make the base, then used the rest to make the back and top.
We used two wooden blocks to raise the shaft sufficiently to allow for clearance when the wheels were fitted to the shaft.
Here is a picture of the shaft as supplied to us
The frame is made from bits of wood we had lying around in the workshop mainly 2” x 1/2”.
Next we cut a hole in the back sheet to allow for the drive belt to pass through to the motor , once this was done we made a frame across the base to secure the back sheet to.
Next we mounted the shaft in place on the base sheet, all marking out and measuring was done using the mark1 eyeball, nothing technical here!
Once this was mounted we constructed a box type arrangement around the pulley area on the shaft to protect it from all the water and muck. (see the preceeding picture)
Then we mounted the motor at the back of the base on rails to allow for belt tension adjustment, this can be clearly seen below:
Now to the boring bit, we gave it many coats of exterior paint and after they had fully dried we applied a coat of plastidip wherever we could, just to make everything waterproof and completely seal all joints.
We have two wheels mounted on the shaft, one is an 8” x 2” 100 grit diamond wheel, this thing is ferocious, and really shapes rock quickly, also does a good job on finger ends as well if you are not careful!
On the other end of the shaft we have mounted an 8” x 3” expanding rubber drum,
We slip silicon carbide sanding belts over this covering all the various grits that we need (belts pic)
We opted for the 8” diameter wheels simply because we wanted the maximum grinding area width that we could get, this set up would work equally well with 6” wheels as well.
Ongoing things to sort out with the design:
1. a good water supply set up that wets the whole width of the wheels
2. should have made the lower splash tray at the front a few inches bigger so that it catches all of the spray from the wheels.
Sources of supply for the major components:
The shaft was purchased from ABC polishing, it’s called the polishing spindle and can be found at:
The motor was purchased from Tony at Goldcrest Technologies, you can find his shop on E-bay here:
And the motor description is as follows:
Electric Motor Single Phase 0.25kw 1400rpm (Made in EU)
Note: these motors are really good, when we are cutting and polishing they run for a good 8 hours a day with no complaints.
The expanding wheel cam from Manchester Minerals who can be found here:
The drum we used is part number on the above page: Ref: 17-047
The belts also came from this supplier and can be found on the same page under part number: Ref: SiCBelts
The diamond wheel came from an Ebay seller in the US, but you could also use a silicone carbide wheel which are supplied by Manchester Minerals as well on the same page under ref no: Ref: SiCWheels
The Plastidip paint we used can be found at //www.plastidip.co.uk
Here are a few pics of how I have mounted the motor, byt using Dexion plate it allows me to move the motor back and forth to get a good tension on the pulley belt:
Alan asked if I needed to modify the spindle to accept the wheel, well there was no modification needed, I hope the pictures below help in understanding:
This is the spindle I purchased from ABC Polishing:
A Close up of the Left Wheel:
A close up of the Right Wheel