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 Post subject: Possibly doing some diamond cutting in the future...
PostPosted: Fri Feb 28, 2020 11:41 pm 
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It looks like this particular forum has been slow for a while, so I'll post a new topic and see if anyone familiar with diamond cutting is still here!

I've been faceting colored stones for quite a few years now. At the time when I built the base for my faceting machine I made it with the possibility to be used in the future for diamonds(more power and higher RPM than a typical faceting machine).

After all these years, I still haven't tried to cut a diamond yet... but I do have some questions as I consider doing so in the future.

I've seen many people mention that it CAN be done on a standard faceting machine(slowly). I may consider starting with this option to see if I think it's worth investing in more equipment. Obviously, the long term solution would be to get/build a proper diamond cutting tang that can mechanically hold the stone, but in absence of that, what type of adhesive should be used for dopping? I've seen black "diamond cutters wax" before, but I've only ever heard of people using it for faceting colored stones... and it sounds like it still melts pretty easily with as quickly as diamonds heat up. I've seen diamonds soldered to metal holders for industrial applications, would that be an option?

I've also seen conflicting information on the abrasive used for diamond cutting too. I've seen where some people go through the same steps as a colored stones, with a rough lap, a pre-polish lap, and a polish lap... but I also seem to remember reading an older book on diamond cutting where it said the grit size is not important. It sounded like a "mix" of sizes is used across the entire scaife, and the only difference is that the stone is cut in some areas(running band?), and polished in other areas (polishing band?). The book made it sound like the only difference between cutting and polishing was the location on the scaife, the way the stone is moved, and the amount of pressure applied. Was this perhaps an attempt to describe a scaife that was charged with different size diamond powder in different areas(ex: coarse on outer edge, pre-polish in the middle, and polishing on the inner edge)?

Another thing that has alluded me so far is a good source for the correct cast iron lap/scaife. My machine is primarily set up as an 8" machine, but I do have room to go up to 12" if necessary. I'd like to stick with 8" for simplicity initially. I've read that there are certain grain structures that are required for these laps. That makes sense to me, but I wonder if it would be possible to make a lap from something else already made from cast iron I thought about making a steel lap for strength/safety, and cutting out some of the middle to add a cast iron section for the actual cutting surface.

I'm not afraid to design / machine / build new equipment / components as needed here if necessary, so anything is a possibility!

I hope some of the forum diamond cutting experts are still around to answer some of these questions!


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 Post subject: Re: Possibly doing some diamond cutting in the future...
PostPosted: Sat Feb 29, 2020 2:29 pm 
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Tom? Hello? Is there anybody out there?


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 Post subject: Re: Possibly doing some diamond cutting in the future...
PostPosted: Thu Mar 19, 2020 6:28 pm 
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It's not practical to facet diamonds on a colored stone faceting machine. To achieve any kind of productivity, you require faster wheel speeds, heavier wheels, and special holding fixtures.

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 Post subject: Re: Possibly doing some diamond cutting in the future...
PostPosted: Thu Mar 19, 2020 11:23 pm 
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I realize it's not practical for full production, but I wouldnt mind it for a few stones(or re-cuts) to see if it's something I'd want to invest more in to get the "right" equipment.

My current machine is capable of a 12" wheel running at 3500 RPM without any special modifications. I could probably even larger diameter too, or bump up the speed if needed to get the surface speed higher. I don't remember what most commercially available colored stone machines run at, but I seem to recall that I built my machine significantly faster than many of the commercially available options I considered.

My questions are more about making a reasonable attempt and making a couple nice stones than practical production cutting.


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 Post subject: Re: Possibly doing some diamond cutting in the future...
PostPosted: Fri Mar 20, 2020 7:39 pm 
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I mentioned that the faceting fixtures are entirely different than those used for colored stones.
I have cut colored stones since 1980 and diamonds since 1981. I would not waste my time attempting to cut diamonds on a colored stone faceting unit. I can think of many more constructive things to experiment with.

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 Post subject: Re: Possibly doing some diamond cutting in the future...
PostPosted: Fri Mar 20, 2020 8:55 pm 
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I am 100% with Tom on this issue. The faceting head is not up to it, too much heat, no way to maintain orientation for the proper (softer) cutting direction, the laps are not up to it, the platen is not up to it. Even if you somehow managed to get through it, it would not be very enjoyable.


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 Post subject: Re: Possibly doing some diamond cutting in the future...
PostPosted: Fri Mar 20, 2020 9:56 pm 
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So If I were to buy/build something specifically for diamond cutting, what would you recommend I start with?

I understand why the fixtures are entirely different, but I've seen several variations and I don't know which(if any) are the better option, or how many variations may be required.


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 Post subject: Re: Possibly doing some diamond cutting in the future...
PostPosted: Sat Mar 21, 2020 5:12 pm 
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Mike1187 wrote:
So If I were to buy/build something specifically for diamond cutting, what would you recommend I start with?
Having attempted 38 years ago what you seem to want to do, I advise you to not bother. I put considerable time and resources into that project. I learned that I wasted my time and money.

Mike1187 wrote:
I understand why the fixtures are entirely different, but I've seen several variations and I don't know which(if any) are the better option, or how many variations may be required.
The table requires one type of dop, the crown requires another type of dop, the pavilion requires another type of dop, and the girdle requires a special dop. Each dop requires some special skills.

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 Post subject: Re: Possibly doing some diamond cutting in the future...
PostPosted: Sat Mar 21, 2020 8:50 pm 
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This is perhaps one of the most interesting things about diamond cutting.... Whenever asking a diamond cutter about learning how to cut diamonds, their response is almost always "don't do it."

Its like the first rule of diamond cutting is "Don't talk about diamond cutting" [-X LOL

This is completely opposite of what I see from a lot of colored stone faceters. Many of them are proud to share what they know and to help others learn, but it does not seem to be the same for diamonds. What little accurate knowledge I have on diamond cutting is either from books that are fairly old, or from a few diamond cutters I talked to years ago who were willing to share some personal experience. This was at a time when i was not really considering diamond cutting, so I didn't ask all the right questions.


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