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Questions about sphere making

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jakesrocks
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« Reply #15 on: March 19, 2015, 06:57:27 pm »

Great links and great replies.  I think that the only question I have at this point is how big the cutter cups should be relative to desired sphere size.  As the number of cutter cups is added, I understand that fewer will fit on the sphere.  I'm guessing that cups should be larger rather than smaller, and small enough so that they don't touch each other.  Is this right?  Thanks.


I don't know if it has ever been narrowed down to an exact science, But I'd use 2/3 to 3/4 the diameter of the sphere you want to make. You want your rough sphere to sit deep enough into your cups to prevent it from popping out of them. As you go through the different grit stages, your sphere will get  a little smaller, and will sit deeper into the cup. Too large of a cup and you run the chance of the sphere sticking inside of one of them.
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« Reply #16 on: March 19, 2015, 07:24:00 pm »

thanks
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« Reply #17 on: April 16, 2015, 10:56:21 am »

Any reason you can't charge the iron or brass cups with diamond powder?

The Chinese are offering it for peanuts these days, and the old-school faceters charge their own laps, surprised I haven't heard about it.

Diamond brazing rods seem like a nifty solution too, if you've got the welding equipment.
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« Reply #18 on: April 16, 2015, 01:29:57 pm »

Any reason you can't charge the iron or brass cups with diamond powder?

The Chinese are offering it for peanuts these days, and the old-school faceters charge their own laps, surprised I haven't heard about it.

Diamond brazing rods seem like a nifty solution too, if you've got the welding equipment.


Iron & brass cups would probably be too hard to take a charge & hold it. If a person had lathe skills, and access to a metal lathe, cups could probably be turned out of copper or tin which would both hold a charge. But you'd need a set of cups for each grit stage. with iron or brass cups, you just clean them & go straight into the next grit.
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« Reply #19 on: May 24, 2015, 09:10:57 am »

Heh, heh, heh.

A good tip, thanks for it. I just happen to know a master machinist with a metal lathe and time to kill.

Now, copper cups, hrm.

Maybe I should finish my metal casting furnace and cast them myself... or can you buy copper cups?
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« Reply #20 on: May 24, 2015, 10:54:26 am »

I've never seen copper cups offered for sale. If you have the casting equipment, you could certainly cast your own in several sizes, and get your machinist friend to true them up & put a finish on them. He could also cut the internal threads for your shaft adapters. Just remember that you're going to need a set of cups for each diamond grit size, plus a set of polishing cups.
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