Faceting speeds

Faceting speeds
Does anybody have a recommended list on the speeds for faceting ?
Like grinding versus pre- Polish versus polish.

Your grinding speeds will depend on how much material you are taking off, whether the material will take shock if you are using a coarse lap, and how much you will need to cut and look. Obviously you cannot go too fast when approaching an end point. On my machine, with a hundredth of a degree indicator, I can gauge how fast the cutting is going and come right up to the end point without looking. I just have to be able to see the digits progress and set the speed based on that. If you are doing a cut and look sequence, you’ll just have to do a trial and error to see how fast the material is coming off. You can count the seconds off mentally and figure out how long your cut is likely to take and stop in time to look. I would say you could use 100 to 300 rpm in general, maybe faster if you are hogging off rough, at first. However, I would recommend sawing ratheer than hogging off a great deal of material, as the coarse lap will probably lead to more subsurface damage than a saw blade. Pre-polish would be much slower, as you are taking off very little material in most cases. 25 to 100 rpm, maybe? Depends on whether you are taking off much material and whether you are using 3K or 8K diamond. Polishing speeds depend on what works. Some types of polish work at high speeds and others at quite low speeds or even sweeping the lap while stationary. It is all an alchemy of pressure, polish type, lap type, lap wetness/dryness and speed. Obviously another issue is how big the facet is, which is why star facets are often brought in on a stationary (or nearly so) lap. Sometimes you can move facets a bit while polishing…

I hope this is of some help. Experience is the best teacher. In cutting, use the fastest speed that will let you get the accuracy you need without overcutting. This is where the very accurate machines like the XS3, Mark V and UltraTec help, letting you cut faster without looking until the very last. Of course, all bets are off with very finicky material or cleavages that are prone to open.

It will all good information thank you very much !

Well said Roy. For me its feed vs speed . Feed being your sweep speed and how heavy or light your hand is. Cooling can all so be an issue slow and heavy hand can cause heat damage to some stones. Too fast and water and or polishing compound ( mostly water born oxides) can be slung off the wheel too fast.That is some of the stupid stuff i did anyway.Only things you truly own in life are your mistakes every thing else you had help with, not too many people will say they helped you make a mistake :relaxed:

With everybody’s help I’ll try to avoid my mistakes !
Mark :medal_military: