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 Post subject: Re: Rubies
PostPosted: Thu Mar 18, 2021 6:42 pm 
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You would need to retrofit for water feed, it is more for the metal shop. That is not really applicable for lapidary purposes. If this is something your serious about for the long term then Diamond Pacific, Cab King, Covington, Lortone, Highland Park are some of the US manufacturers, there are others just do some research and there are many youtube videos on how to cab, once you get a little experience, you will acquire your own preferences. I would suggest a Diamond Pacific Pixie unit, self contained, desktop for needed space, good for small cabs say 15-16mm nominal sizing and smaller.[/quote]

Alright I'll have to wait then. I am serious about doing this long term, I really enjoy it. I'm just not sure where to cut corners and whats worth spending the money on. Right now I would rather upgrade the graves machine head, or for that much, the whole thing if it's worth it. I can't really say that it's been bad, the machine is consistent but not precise.


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 Post subject: Re: Rubies
PostPosted: Fri Mar 19, 2021 12:39 am 
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1bwana1 wrote:
j.mcgee_1985 wrote:
1bwana1 wrote:
You should probably clarity enhance the emerald. It is a standard and accepted treatment for Emerald and will likely make the stone much more attractive.


Which type of treatment do you recommend?



Crack filling under vacuum, pressure and heat with either Opticon polymer, or natural Cedar oil.


I was just watching a youtube video about this then I look down and in the comments is a very detailed description on how the process works, written by you of course :) small world. It won't be real soon but I want to try this with opticon. I think the acid you mentioned would work well for these also. I'll save them until I can get a little vacuum chamber.


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 Post subject: Re: Rubies
PostPosted: Fri Mar 19, 2021 2:14 am 
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The least expensive way to make small corundum cabs with a faceting machine is to get someone to turn up a hard-wood lap for you, with three round-bottomed concentric grooves about 1/2 inch wide. Load the outer groove with 600 mesh diamond, the middle groove with 1200 mesh, and the inner groove with 14000 mesh. Use a light oil as lubricant. Preform the dopped cab on a flat 600 mesh faceting lap, getting it as smooth as you can, spinning the dop with your fingers. Then smooth off the remaining ridges in the outer groove of the wooden lap, and proceed step-wise to polish, cleaning the stone and dop well before each successive step. Make sure to remove all the 600 scratches with the 1200 mesh before polishing. If you want to use more diamond steps, get two laps made.

If you can find or have made a fitting with copper cups and retaining ring, that is even more convenient. It is a threaded cylinder that screws onto the spindle thread, with interchangeable copper cups that you load with diamond paste. Mine came second-hand without sufficient cups but I had some made by a silversmith.
Attachment:
Cab fitting for faceting machine.JPG
Cab fitting for faceting machine.JPG [ 194.3 KiB | Viewed 1194 times ]


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 Post subject: Re: Rubies
PostPosted: Fri Mar 19, 2021 10:11 am 
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Great idea Duncan, thanks for sharing. Seems like a wood lap would work really well minus water. I had a polycarbonate lap I used for polishing and for me it worked better than the copper until it became contaminated. I scratched it up trying to clean it off and ruined it though. Could you get a slightly larger bowl and drill an arbor hole and just fix it straight to the machine? I don't really understand why its in the copper cup.


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 Post subject: Re: Rubies
PostPosted: Fri Mar 19, 2021 11:02 am 
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The blue fitting screws onto the spindle thread of the faceting machine. There are several interchangeable copper cups to take different diamond grits. The brass-colored ring screws onto the thread at the top of the blue fitting, to hold a copper cup in place. If you know someone with a machine shop they may be able to turn up a suitable fitting for you. Then you have to find someone who can work 1 mm thick copper sheet into hemispherical cups with a small lip to be held down by the brass ring. You need a different cup for each grade of diamond paste. The cup enables you to rotate and swivel the stone on the dop to get an even dome to the stone. The cups are only 4 cm in diameter.
The grooved hardwood lap option is simpler, especially if you are making small cabs. If possible, get it turned end-grain on, like a horizontal slice through a tree stem. It needs to be well-cured wood, so that it doesn't split. The lap can be quite thick, as long as you can hold it down with the spindle nut. Again, you need to rotate and swivel the stone in each groove to get an even dome.


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 Post subject: Re: Rubies
PostPosted: Fri Mar 19, 2021 12:25 pm 
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Graves used to sell star cups, made of copper. But if you can have them made all the better.

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 Post subject: Re: Rubies
PostPosted: Fri Mar 19, 2021 2:05 pm 
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I think I understand, let me see what I can come up with. Thanks for the ideas!


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 Post subject: Re: Rubies
PostPosted: Fri Mar 19, 2021 2:39 pm 
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Here is a pic of some cups I made for a job we had awhile back for small star rubies needed for the GIA education program. Follows what Duncan is suggesting as alternate tools on a budget. There made of maple, fit in a drill chuck clamped into a vise. Variable speed drill worked the best as well as reversible.

Attachment:
20210319_110602.jpg
20210319_110602.jpg [ 292.49 KiB | Viewed 1165 times ]

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 Post subject: Re: Rubies
PostPosted: Fri Mar 19, 2021 9:51 pm 
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That's cool! I like that you guys make your own tools.
I like both ideas, I'll try and find someone who can make a wood lap, and I'm going to see about getting some small pieces that would fit in a drill.
Putting grooves in a flat polycarbonate lap would be pretty simple also.
Seems like a fun little project :)
Thanks guys!


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 Post subject: Re: Rubies
PostPosted: Sat Mar 20, 2021 2:24 am 
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j.mcgee_1985 wrote:
Putting grooves in a flat polycarbonate lap would be pretty simple also.

Wood should hold the diamond grit better. I would also consider grooves cut into a cast iron lap...


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 Post subject: Re: Rubies
PostPosted: Sat Mar 20, 2021 1:35 pm 
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Ok, I'll try and find a wood lap.


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