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November 22, 2009, 11:04:27 am
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Assembled Cabochon Tutorial

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Bluesssman
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« on: January 07, 2009, 10:09:04 pm »

I am getting ready to try glueing some pieces (I am sure there is a name for what I am doing) together to be cabbed. Would using aluminum foil as a surface to do the glueing work, or would a different surface be better?
« Last Edit: January 09, 2009, 02:03:22 pm by Taogem » Report Spam   Logged

bobby1
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« Reply #1 on: January 07, 2009, 10:19:38 pm »

Wax paper works, too.
Bob
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Bluesssman
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« Reply #2 on: January 07, 2009, 10:32:03 pm »

Bob, being the lazy kind, which would you recommend?
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Taogem
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« Reply #3 on: January 07, 2009, 10:49:33 pm »

Are you getting ready to try some of the intarsia domed type cabs a try? Like the ones theImageOne and Lavenderfish have shared?



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Bluesssman
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« Reply #4 on: January 07, 2009, 10:54:07 pm »

Yes. Tomorrow I shall attempt to do the glueing. It will be a little different from the others. I will post how the experiment does!
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bobby1
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« Reply #5 on: January 08, 2009, 09:29:57 am »

Any generic wax paper from the grocery store will work.
Some people that do intarsia use super glue, but for gluing rocks together I have always preferred Epoxy 330 because I can rely upon the clarity of the adhesive not to have bubbles or discoloration.
I do quite a lot of what I call "assembled" cabs or stones including doublets and triplets with differing materials on the front or back.
Here is a large "Cab" (4" across) that I completed with a clear Quartz backing. After my dad died I was going through his lapidary and jewelry stuff and I came across this in pieces. When he was working on this it kept coming apart because there wasn't enough surface contact area between the edge of the stones and the metal strips. I backed it with a large piece of synthetic quartz about 1/8" thick. This allowed me to finish the piece because it didn't keep  failing at the joints. I always display this one in my show case in honor of my dad.

He is an edge view showing the Quartz on the back.

Bob
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Bluesssman
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« Reply #6 on: January 08, 2009, 10:35:13 am »

Thank you, Bob. What a nice thing to do honoring your father in the way you do!!
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Taogem
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« Reply #7 on: January 08, 2009, 02:13:35 pm »

Man..... I have got soooo much to learn.

Absolutely beautiful assembled cab Bob. The look of the metal strips is really something too.

theImage1 sent me several pieces of very thin pieces of black agate and also a very nice piece of quartz along with some others. All sent with the intent to be used for the purpose of backing like this.

When I get set up with a flat lap type set up for the purpose of making similar cabs, I know these will come in handy for backing.

It's always about the funds... But looking forward very much to trying some assembled or intarsia type cabs.

Thanks for sharing your Dads assembled cab. It's beautiful ! Smiley

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« Reply #8 on: January 08, 2009, 07:11:41 pm »

I don't have a flat lap. I do all of the surfacing on sheets of window glass using tumbling grit. Flat laps are too slow.
If you want I can describe my process and show more examples.
Bob
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Taogem
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« Reply #9 on: January 08, 2009, 07:55:39 pm »

I don't have a flat lap. I do all of the surfacing on sheets of window glass using tumbling grit. Flat laps are too slow.
If you want I can describe my process and show more examples.
Bob

I think I can speak for everyone when I say........ You bet !  Smiley

It sounds really interesting.
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bobby1
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« Reply #10 on: January 08, 2009, 09:53:36 pm »

I'll start with a photo of a triplet (three layer) assembled cab.

This is a piece of Woodward Ranch black plume. Often this material has fantastic plumes but it is so dense and black that the plumes don't show up unless you cut it real thin. If it is thin enough to show the plumes then it is too thin to stand alone as a cab. I started by slabbing is at about 1/16" thick. I then flattened  a slab of  translucent light grey agate. Next I flattened the Plume Agate and glued it to the translucent Agate. After the glue set I then ground it on the grinding wheel until it was maybe 1/32" thick. I then hand lapped it on a piece of flat glass using 220 grit tumbling grit and water. I kept going until I got the plumes that I wanted to show up. I then glued it to a flattened slab of clear Synthetic Quartz. This is what the "sandwich" looks like from the side. The translucent Agate is on the left, the Plume in the middle and the clear Quartz on the right.

Here is a look at the "sandwich" through the translucent Agate.

Here is a look from the clear Quartz side.

At this point I cabbed the "sandwich" , polishing both the front and back.
And now the detail:
1. Use a fairly new piece of flat glass. After you have ground a few slabs on it the center will become dished. I use a piece about 6" square. Put a pinch of 220 grit abrasive on the glass, wet it slightly and start moving your slab around in figure 8 circles. Keep grinding while adding additional pinches of grit and water as the grit wears down. Stop once in a while, rinse the slab off and dry it. If you have an even frosty appearance with no evidence of saw or grinding marks you are ready to go to the next grit. On a 2" diameter slab this coarse grind should take about 15 minutes.
2. Rinse the glass thoroughly. Go to the 400 grit step and repeat the grinding activity of moving in a figure 8 pattern until the 220 grit pits are looking much smaller.
3. Repeat the above step with 600 grit.
4. Clean everything up (it gets a bit messy). Set this slab aside and repeat the above steps with the slab that you are going to glue the first one to.
5. Wash the slabs in hot soapy water, rinse them in hot clean water and Don't touch the surfaces to be glued with your fingers. Using a clean paper towel, wipe both pieces with Denatured Alcohol.
6. Place both pieces on a small paper plate under your "gooseneck" lamp with a 100 watt bulb. Let them heat for about 10 minutes. On a small piece of WHITE paper, mix the two parts of the Epoxy 330 by swirling it together with a tooth pick. Don't "whip" it together because it will introduce bubbles. From here on bubbles are your enemy! Mix it until you can't see any swirl patterns in the Epoxy. Mix for one minute more. Slide the piece of paper under the lamp and heat it for about 3 or 4 minutes until the Epoxy mixture becomes rather liquid. The bubbles should have dissipated by this time.
6. This is an important step! Pick up one of the slabs by the edges and scoop some of the adhesive onto  it. Spread the Epoxy slowly and carefully trying not to introduce bubbles. Lay it aside and do the same to the other slab. Make sure you are spreading the Epoxy on the prepared sides of the slabs!
7. The most important step! Lay the two slabs together by touching the edges in a "V" and move them together as you squish the Epoxy to the side away from the "V". This way you are not trapping a big bubble between the slabs. Grip the two slabs betwen the fingers on one hand and slowly apply pressure as you move the pieces a slight amount against each other. Your objective is to squeeze the excess Epoxy and any possibly entrapped bubbles out from between the slabs. When you feel the slabs dragging slightly against each other stop moving them and hold the newly asembled "sandwich" at a steep angle to the bulb in the lamp and look for any entrapped bubbles. If you see any go back to squeezing and moving the sabs to get the bubble worked out to the side.
8. Place the "sandwich" back under the lamp and continue heating for about 30 minutes. Turn the lamp off and go to bed. You've worked hard so far and you need a good nights rest!
9. Wake up refreshed and grind or sand the prepared color (plume or whatever) layer down to the desired pattern. Go through the three grits and set this "sandwich" aside. Prepare the final slab surface by going through the above three grinding steps.
10. Glue the two slabs together as above. When the Epoxy is set up hard cab as usual.
A warning! Don't use 5 minute Epoxy! You don't have enough working time before it starts to set up!
Some more pictures:
A very thin slice of Dendritic Agate with a clear backing.

A side view.

An Australian Opal Triplet (clear Quartz top, a thin layer of Opal and a Basanite back).

A Spencer Opal Triplet.

Another Spencer Opal triplet.

Have fun making assembled cabs!
Bob

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« Reply #11 on: January 08, 2009, 10:43:28 pm »

Bob, that was fantastic. Proves you don't always have to have expensive equipment to do really nice work. Thanks for sharing!!
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« Reply #12 on: January 09, 2009, 02:49:07 pm »

That is the greatest !

I guess it's safe to say that we need to replace with new glass after a few times due to the resulting concave.

I wish I had these powdered abrasives in the varieties needed. The one and only abrasive powder I have is an oxide for polishing.

Will have to order all the different abrasives.

I have not searched yet, but guessing these are a silicon carbide type powders?



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« Reply #13 on: January 09, 2009, 03:11:58 pm »

I just use scrap pieces of glass. Sometimes you can talk your local hardware store into giving you their scraps. If not they will sell them cheaply. A piece of glass will do 8 to 10 cabs before it gets dished in too much. You flip it over and use the other side before discarding it.
The silicon Carbide grits are those that come with rock tumblers. They come in 1lb quantities. 1 lb of 220, 400 and 600 is more than adequate to do many stones.
Bob
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