What opal cutting wheels do I need is an often asked question. In this video, Justin will show you exactly what your options are.
We start at the beginning with a 200-250 grit wheel for the rubbing process. Beware that 120 grit is too rough and will destroy your opal.
Next we move to a 300-380 grit wheels for the next stage of rubbing by hand.
The wheels I use are mostly 8 inch wheels as you get more life out of them but you can also use 6 inch wheels. At this stage I talks about the difference between sinted wheels and coated wheels.
Sinted wheels are much more expensive due to diamonds being impregnated in the wheel up to 5mm thick. A coated wheel also has diamond grit impregnated but only on the surface. A sinted wheel will probably last you a lifetime (I still have some which I learnt to cut on 30 years ago) whilst a coated wheel may only last six months.
The next stage wheel is the 400-600 grit which will help you get a nice smooth shape on the stone. From this point there are two ways to go.
Option 1: 600 grit soft Nova wheels. These wheels are still diamond impregnated however they are cushioned. Following on I go to a 1200 grit Nova wheels for what is close to pre-polish. Now you can go to a 5000 grit but I don’t think its necessary.
Option 2: Flat Lap wheels. This wheel is a worn down sandpaper wheel. You wear it down buy using a piece of rough potch (common ) opal to make the surface shiny.
The Final Polish
With a flat lap you may use pumice next but the final polish regardless of option is the felt wheel impregnated with cerium oxide. This is what gives you the extra fine polish. Watch the video with Justin for more information on this. We also now sell cerium oxide which you can purchase HERE.
What machines do I need?
There are no particular brands that you need to buy. I use an Australian brand called Gemmasta but there are many others out there just as good.
All the wheels can operate together without risk EXCEPT your final polishing wheel. The felt wheels must always be separate from the others to ensure that impurities are not carried through. If larger particles do get onto your felt wheel you will compromise the final polish and the likelihood of putting scratches in your stone will be high.
So there you have it – a guide to opal cutting wheels. I hope we’ve helped you out and as always, please leave us any comments, optioning or questions you might have below.
I love your smile. Thomas.
what kind of felt wheel to use gemstone ? medium or hard
and how much the price for felt wheel 6″ in your country, because in my country so hard to find it
Justin, can I use my #220 “turbo” wheel for preforming opal or would it be a bit too aggressive? It’s a metal-bonded cabbing wheel with diagonal channels running across the face. It grinds harder things like agate fairly quickly.
Cheers
Hi Lefty You can but I would only use it for taking excess rough you don’t need off a piece. When you are getting close to the color, stop and use a finer wheel. Also make sure you are using water with it.
I also see you use soft-backed wheels. My Cabking came with hard-backed resin bonded wheels from #280 up to #3000. I’ve always thought I would get more perfect shaping with a softer back since cabbing and faceting have opposite requirements – with one you want a hard abrasive surface to get as flat a face as possible but with cabbing you want a smoothly rounded surface and that isn’t as easy and is more time-consuming to achieve when the wheel is hard, or so it seems to me anyway.
The hard bonded wheels will def be more difficult to get a cabochon on the stone compared to the nova soft diamond wheels. It is a great expense to buy a set of soft nova but all you really need for opal is 600 grit and 1200grit then use the cerium oxide on a felt wheel after that.
Thanks Justin.
I didn’t originally realize that you could get soft wheels since the hard ones came standard with my machine when I bought it and my club only uses hard ones. I think they would be better for cabbing pretty much anything.
If I went to the expense, should I reserve them only for working opal? I’ve cabbed a lot of agate and petrified wood as well as other things significantly harder than opal – it seems likely to me that these stones would wear out expensive wheels faster than opal while not actually being worth anything.
Cheers
Hi Lefty
You are on the money their mate they will wear down much faster on agate and similar semi precious stones. If money isn’t an issue I would say use the soft ones on everything but they do cost in excess os $200 a wheel