Our Home Made Cabachon Machine

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.

our home made cabachon machine

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

Picture showing the shaft and pulleys

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.

The hole for the drive belt

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:

The motor mount

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!

The diamond grinding wheel

On the other end of the shaft we have mounted an 8” x 3” expanding rubber drum,

The 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 http://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:

Cabochon Machine Spindle
Cabochon Machine Spindle

A Close up of the Left Wheel:

Close up of left wheel spindle
Close up of left wheel spindle

A close up of the Right Wheel

Close up of right wheel spindle
Close up of right wheel spindle

Homemade Lapidary Equipment

The cabachon machine has seen quite a lot of service since it was built last summer and has stood up to the test of time so far

This weekend I will be taking some pictures of our homemade cabachon machine and writing an artcile on how we made it. This will also include details of Uk suppliers where I managed to obtain the parts to make the machine.

The cabachon machine has seen quite a lot of service since it was built last summer and has stood up to the test of time so far, we have ground, shaped and polished many types of semi-precious gemstone on the machine, including amethyst, sodalite, rose quartz, petrified wood, pebbles found in the fields and many more varieties with a large degree of success.

We also use the diamond grinding wheel on the machine to make pre forms for the tumblers.

It’s not a particularly pretty machine to look at when compared to the commercially available machines, but what we have lost in looks we have saved in terms of costs and nothing in functionality.

I will get the details posted over this weekend, plus make a start on cutting some of the black flint I recently found, it should polish up really well for use in the jewellery.

When is black agate not black agate – when its flint!

Well I had a “field day” no pun intended, as you can see from the picture I filled my boots, this field has lumps of flint all over the place.

Yep, I was mistaken when I thought I had found a lump of black agate in a field while on a recent courier trip, Sparkles has kindly pointed out to me that it was in fact high grade flint I had found!

Anyway as I said in a recent post, I was going to passing by this particular field again today, so I left home early to allow myself some time to do a bit of rock hounding again.

Well I had a “field day” no pun intended, as you can see from the picture I filled my boots, this field has lumps of flint all over the place. I think I must have picked up about 7kg’s of the stuff and would have collected more but I was on the bike, so was aware of the extra weight I would be carryng after I had collected the courier package further down the road.

Black flint

But as you can see there are a good range of shapes and sizes in the there, plenty of cab material and a good few loads for Shalini’s tumblers too.

I am sure I will be passing this place again in the not too distant future, maybe I should pick up some more.

Get the feeling that Shalini will be prepareing the tumblers this weekend as it looks like they in for some serious work very soon.

Anyway all for now


Black Agate – What A Find

I peered into a field and was amazed to see it was literally littered with lumps of agate

In my other life as a motorcycle courier I often pull up at layby’s for a convenience break. I recently did this on a trip down the A1, during my stop I peered into a field and was amazed to see it was literally littered with lumps of agate, some were of a good tumling size, but there were also many other larger pieces in a variety of colours.

Of course, I spent a little longer there and investigated further and was rewarded with a truly magnificent lump of black agate, this should provide a large number of freeforms and cabs and will look beautiful when wrapped in sterling silver wire, so I think the saw will be cranked up later this week when I have some spare time.

Black Agate

I have another courier trip planned for Tuesday which takes me past this location, so I will be leaving quite a bit earlier to go to the pick up point which will allow me more time to to do a bit of rockhounding in this area, so lets see what else this field produces.

Over here in the UK we don’t seem to have the abundance of semi precious stones just laying around like other rockhounds in America enjoy. But when you find an interesting lump of agate, it makes it all the more rewardng when you cut and polish it into a really nice piece.

Carnelian Rough To Finished Pendant

Here we present a finished Carnelian pendant supported by a piece of rough Carnelian to illustrate the sorts of things we do in our workshop.

The cabachon was first cut as a slab from the rough rock and was then shaped on our cabachon machine and finally polished on a felt wheel with cerium oxide polish.

The cabachon was then wrapped using sterling silver round and half round wire.

I must admit that I find Carnelian to be one of the most rewarding semi precious stones to work with.

Carnelian Cabachon

This item is currently on display at Greensleaves Florists at Stamford garden center


Time to prepare the workshop for use again

Timw to get the Lapidary workshop ready for use.

Well it’s starting to warm up a little here in the UK now so it’s time to start thinking about getting the machines in the workshop prepared for use again. It’s been too cold over the last few months to work out in the workshop so everything had been dormant out there.

So, I think I will spend some time tomorrow getting this ready for use again, the saw oil will need changing as it’s been in the sump for quite a while now, also have to do a few mods on the coolant system on the cabochon machine, the gravity feed we used last year was OK but didn’t provide the correct flow rate of water onto the wheels, so will be experimenting with a fish tank pump soon to see if that will improve matters.

The rock tumblers will also need a good clean and lubrication before they are pressed into service again.

We had bought a wood burner for use out in the workshop but we never quite got round to installing it, which I am glad about now. Why, well we changed our car which is much longer than the previous model so it encroaches on the space around the Lapidary benches, so it will be a complete reconfiguration of the benches as well before we can start production again.

We also have a quite a lot of stone to sort out as well, much of this has been collected from the local fields when out with the dogs, it’s mainly local agates but it polished to a really lovely shine, there also some nice pebbles too which can be cut and polished or put in the tumblers.

Before I go here is a nice piece of Carnelian we did last year from a rough nodule:

Cutting and Polishing

Welcome to our messy world of Lapidary, yes Lapidary is very messy but extremely rewarding, it really brings out the “creative” in you, sometimes with realising it.

So what is Lapidary, well as far as we are concerned it’s all about taking a lump of stone, be it a semi precious piece from our stocks or a piece of agate I have picked up in the fields when walking the dogs and then turning that lump of rock into a unique, highly polished item that can be used in Shalini’s jewellery.

Basically, it’s not rocket science but does require a good amount of care as it employs some pretty ferocious machinery, and the proximity of the fingers is always very close to a fast spinning saw blade or grinding wheel. Not to mention the lubricating water/oil mix that is used on the saw, eye protection must always be worn during this process.

So where do we start, well we grab a lump of rock and slab it on the saw, by slabing we mean we cut the rock into slices, usually about 6mm thick but this depends on the end use we have in mind, so it can vary.

After we have our slabs we sometimes use a template to mark the shape of the finished item, sometimes we just use the natural shape of the slab to dictate the outcome.

Next we will go back to the saw and trim the slab to the marked out shape if needed, if we are using the slab natural shape there is no need.

Now we move onto our homemade cabachon machine, its basically a grinding wheel with two wheels on it, one is a very rough diamond grinding wheel that we use for the initial shaping of the piece, this wheel also lover to eat finger nails – be warned. Then its onto the other wheel which is an expanding rubber wheel that has various silcone carbide sanding belts fitted on it. We always start with the most ferocious belt and work our way down to the finer belt which produces a nice pre polished piece.

From here it’s onto the polishing wheel which has a felt pad on it and cerium oxide polish which just finishes off the piece nicely ready for Shalini to mount it in her fine jewellery style.