Thread: Index wheel/gear for facet machine

You may want to see if you can buy some index wheels of a similar diameter from a manufacturer and drill/sleeve to size for your machine. Failing that you could buy some brass gears with the right tooth count off the shelf. Having been involved with making them, I can tell you that the even spacing is crucial and filing them out might look okay but it's going to traumatise the first person to use them when they can't work out why none of the facets line up.

Another approach would be to borrow a dividing head from somewhere and locate the 3 corner file with Vee grooves or use an angle grinder with the wheel dressed to a V shape clamped to two strips of plywood that are hinged together to allow the grinder to take a V cut (seen chainsaws sharpened this way) as it swings up and down.

If you had to have just one index wheel, I'd get a 96 wheel as it does the most common faceting recipes and it will also do everything a 64 index wheel can do. Most common index wheels used are 64, 80 and 96

Edit: There is a guy currently making 64, 80 and 96 aluminium wheels that are 60mm diameter with a 5/8" mounting hole. He sells them with a machine he makes but may be willing to sell them separately but I don't know how much they sell for either. They are batch made on a milling machine using a dividing head just like a gear is but with a V notch instead of a gear profile.

Yes there is such a thing. I'm sure I came across it... somewhere. If you googled something like gear software I bet you'd find it. Of course you could always draw it in your CAD package of choice, print 1:1 on sticky paper and go to town. But maybe heed the voice of experience above.

Hi,
You can produce evenly spaced pies here CGTK - Divider Wheel Generator. Thats at least a start if your happy to file them, maybe with another gear to get the tooth shape...but really to do it super accurately you need a dividing head or rotary table.

Ewan

Pete, can you post a few pictures of this machine? I'm not sure I've ever seen one (at least something called a facet machine).
I did something similar to Bryan's suggestion, only if you use a glue stick and apply it to the blank and then carefully place the paper on, it won't stretch. No sticky paper required.
If you don't have a cad package I could do something in autocad for you I'm pretty sure.
What tooth count wheels are you wanting to make up?

Michael

Additional question - what do you regard as the far reaches of SA?

When cutting facets on a gemstone it's important to have the facets "meet" properly i.e. the corners of the kite and triangle shaped facets just barely touch each other. If the index wheel teeth aren't precisely cut and there are tiny errors, then the facet will be displaced around the stone by a small angle from where it should be. The results in a facet that doesn't meet on one corner (undercut) and goes past meeting on the opposite side (overcut). A skilful facetor can spot this before the final polishing stage and "cheat" the angle by rotating the index wheel with the cheater screw (assuming the machine has one). This is an acceptable state of affairs for one facet that is a little bit out for some reason but when you multiply it by 57 facets for a standard brilliant cut stone that are all subtly out by some small angle error and you have a recipe for going nuts.

Commercial stones from the jewellers as a general rule have rough facets like two ship passing in the night as they are cut by hand in overseas sweatshops.

If this is the original posters first faceting machine, the experience may be enough to turn him off the hobby for good. I think Gemmasta machines are made in his neck of the woods (Adelaide) , it might be worth ringing them for a price on an index wheel. They aren't like change gears on a lathe, most users leave the 96 wheel on their machine and never change it for another.

Have you tried Shelly's lapidary supplies they may may have the index wheels in stock

Hi fxst,

Is this what you are looking for? Gear template generator

Change the pressure angle to 45 degrees to get a more triangular tooth profile.

Regards
Ray

Hi Gaz thanks for your input but I have had the machine for about 10 years and nope don't like the gemaster at all. I have been faceting for sinc about 1980 but haven't done much in the last 10 years. As to filing well as a locksmith I had to do that quite a lot so am accurate enough.
Its all a good trial method and until I can get a dividing head I will try any method if it works and I have a large supply of glass to practice on before I touch my good stuff with home made index wheels.
Thanks Ray just the thing I was looking for As usual the forum comes through
Pete