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

29 thoughts on “Our Home Made Cabachon Machine”

  1. Hi David,

    thanks for getting in touch but sadly I don’t build machines for other people, there are too many regulations to comply with to make it viable.

    best regards

  2. Hi Alan,

    thanks for your message, the anwser is I didn’t need to adapt the spindle ends at all, the left end of the spindle is threaded so was no problem, I just got some large washers to support either side of the wheel. The right side has a pig tail on it, but then it becomes a normal spidle further in towards the pulleys, again threaded.

    Have a look at the new pics in the post, they will expalin it better than I can in words.

    Hope this helps



  3. hi
    great article – my question how did you adapt the ends of spindle they seem to have ends that wouldnt fit the wheels or drums could you send email as i really want to build a similar machine

  4. Hi Dermot,

    I have to agree with them, a stepped three pulley will be an advantage as you will be able to slow things down, especially if you put a polishing belt on your expanding drum, you will be wanting to run a lot slower.

  5. There are several different types of electrical motors for sale on online sites and you can easily place the order online and get them delivered through the fast delivery and shipping process. The electric motors for sale are available in single phase, three phase electrical motors and as well I HP electrical motors. You got to make the right decision for whichever purpose you tool for. Which electric motor is your favorite? We can help you find many for sale.

  6. Dave
    Thanks for the pictures. It does help to see the set up as you have it. I will be ready soon to order my motor and pulley. I got an email from Manchester Minerals It said that a 1/1 ratio was okay with the 1400 motor. They also mentioned that if I were to have a 3 pulley system then I could half & double the speed of the wheel. Will I need this or is it best to stay with 1/1 ratio?

  7. Browsing through your text I have found answers for many questions that have been troubling me for long time now. Its problematic to find professional articles on the web as many those publications are made by a person with only partial knowledge of the topic. Your article is excellent and definitively worth recommending. I’ll return to read more of your texts in few days.

  8. Hi Dermot,

    sorry for the delay I have noe taken the photos of how I mounted the motor, I think you can see from the pics that the dexion plate has slots in it which the bolts travel through, this allows a degree of movemnt backwards and forward to get tension on the belt. Hope this helps



  9. Dave
    I want to have one solid Silicon Carbide wheel and one Expanding drum. Like yourself I think this will give me a bit more flexability. I think the arbor size is 1/2″ I will check this out.
    Thanks for the forth comming pictures.

  10. Dermot,

    are you going to use silicon carbide grinding wheels or the expanding rubber drums with silcon carbide belts, this might make a difference to the RPM’s – not sure. I prefer the expanding drums simply because they are more versatile because you ca simply slip different grade belts on when required as you go through the process. On my machine I have a 100 grit 8 ” x 2″ rigid diamond wheel for the rough shaping which is a permanent fixture, on the other side I have one 8″ x 3″ expanding rubber drum which I use for the silicone carbid belts.
    Regarding motor mounting, yes the motor does need to sit directly behind the pulley so that the belt comes off the pulleys at right angles otherwise the belt might slip off. I mounted the motor on a block of wood which has a peice of right angled dexion plate on each side, because this has rectangular slots in it I am allowed some room to pull the motor back a little before tightening the bolts down, this allows me to get some tension on the belt. Will take some photo’s this week to show you what I mean. Did I ask you what dimater the pulley was on your arbor?


  11. Dave
    Thanks for your help. I am looking at buying my grinding wheels at Manchester Minerals. They sell the ones you bought for your grinder 6″. I can email them to find out what the max rpm they run at.
    Does the grinder run at the same speed or will it need to speed up. Tony asked me if it ran on a 1:1 ratio. He also wants to know how far apart the motor will be from the pulley. I guess the motor will need to sit directly opposit the pulley on the arbor, but fixed on a solid surface.
    He also needs to know the width of the top (widest) of the pulley grove.
    getting there slowly

  12. Hi Dermot,
    I went to photbucket to see the picture, ok as I said before you ned to have a look at your wheels and see if they have a lable on them indicating the max rpm they can run at, you also need to measure the diameter of the pulley wheel on your arbour as we need to establish what size pulley you need on the motor so we can get the wheels running within their specifications. The motors I use that Tony supplies run at 1400rpm, mine are .25kw single phase which have more than enough power to run my 8 inch wheels. If I remember correctly the motors come with a plate for each side which allows for easy mounting with bolts and nuts. One other thought you will need top measure the width of your pulley wheel on your arbor as well as this will tell you what size v-belt you will need, again information that Tony will need. Looking forward to hearing from you, Cheers Dave

  13. Hi Dave
    Well that did not work!!! Can’t see how to send you the picture if you can email me then I will attach it.


  14. Hi Dave I hope this works picture of arbor


  15. Hi Dermot,

    yes please do send me a picture over, also do the wheels have any indication of their maximum RPM on them as this will help also.



  16. Hi Dave,
    I have just bought a Lapidary Arbor which can take 2 x 6″ wheels. I have contacted the electric motor chap about a motor for my arbor. He has asked me lots of questions, and suggested I talk with you to try and help me with my requirements. I wonder if the smae motor as you suggested would be okay. The arbor is 1/2″. Will I need a belt and so on. If I could send you a picture of the arbor it might give you a better idea. Sorry for all the questions at once. Dermot.

  17. Hi Rebecca, you can purchase one of these machines from various places, if you are in the US you stand a better chance than you do in the UK but be warned they are very expensive, this was why I built my own machine.

    The UK source I know of is at Manchester Minerals, take a look at this page:

    One company who I have dealt with in the US is Santa Fe Jewellery Supplies, take a look at this page:

    Another popular machine is the Diamond Pacific Genie, just google it there are plenty of suppliers in the US for this range, finally have a look at Ebay as machines occassionally come up for sale.

    Hope this helps

    All the best


  18. This is a really good read for me, Must admit that you are one of the best bloggers I ever saw.Thanks for posting this informative article.

  19. Hi Paul,

    Yes I got the pulley and motor fromTony at Goldcrest Technologies, I think the pulley was 70mm but I will measure it tomorrow and let you know.




    Morning Paul,

    have just measured the pulley and it is 70mm absolute outside diameter, of course the “V” for the belt is cut into this, you would also need the fitting adapter to fit it to the motor shaft, Tony at Goldcrest supplied all of this for me.

    I have found his motors to be extremely reliable, on good days we have run this machine for 8 hours a day with no problems.

    If I can help anymore give me a shout

    Best regards


  20. Hi

    This is just what I have been looking for.
    Just one question what size is the drive pulley on the motor and did you get from the same company as the motor

    Regards Paul

  21. Hi there,

    glad you found the information useful, the machine is still running quite happily and doing a great job.

    All the best


  22. Hi,

    thanks for dropping by, we build our machines because there really is very little available here in the UK and what is available is very expensive. Buying a cab machine from the USA would be even more expensive when importing it.

    I like the sound of your rough you have, they are huge!

    Have a great day


  23. Wow, i can’t wait to show hubby your site..This ROCKS, he also made many of his Own Machines, from scratch.. We have so many different big boulders, 37lb Jade, 21lb Lapis Lazuli..etc. Your Pendants are soooooo pretty, Thanks for sharing. blessed b~ @cyniraholt hubby twitter is @down4now

  24. Hi Dave, this is absolutely fascinating! A great blog and very good advice. It is wonderful to see how your beautiful jewellery is made, the hard work and thought that has gone into it and the process followed. Amanda.

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