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Post by rockjunquie on Jul 21, 2012 18:10:06 GMT -5
I feel kinda bad. I got this slab on eBay from a really good seller. It is high quality stuff- very primo. I paid good for it. I got it and instead of the 5mm it was 3.5-4mm. I emailed about it and he told me to keep it and refunded me my money, including shipping, before I could protest. I would have sent it back or something. I feel bad for his loss. He's a really good seller and I think he made an honest mistake. Anyway.... my point is... I now have this incredible slab that is really thin. I have never done it before, but I guess I can back it. But, I don't have a flat lap. I think it is too thin too cab. Or, is it? I don't want to waste the material trying. Any and all opinions and ideas welcome.
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Post by Bikerrandy on Jul 21, 2012 18:12:56 GMT -5
Depends on the slab, what is it?
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Post by rockjunquie on Jul 21, 2012 18:17:42 GMT -5
Dude, it's this really sweet agatized Indonesian bird's eye palmroot- you know the kind with the black flames going into tan swirls? I bought one other slab from him with no problem and wanted another.
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Post by Bikerrandy on Jul 21, 2012 18:20:28 GMT -5
If it's agatized, it should hold together just fine. You'll have to go light on putting a dome on it.
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Post by rockjunquie on Jul 21, 2012 18:26:08 GMT -5
See that's what I was wondering. Won't it just be one big flat spot on the top? I'm not so sure I can dome something that thin- but I did do one today that was pretty thin, come to think of it- maybe I can do it. ;D I'll have to try. I hope I can, it's so beautiful.
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Post by Bikerrandy on Jul 21, 2012 18:53:34 GMT -5
If you get the flat spot, just keep rocking the center of the cab on the first wheel (lightly) until the flat spot is gone. This will be good practice for ya ;D
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pporky
fully equipped rock polisher
Member since May 2007
Posts: 1,932
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Post by pporky on Jul 21, 2012 19:11:41 GMT -5
Sounds a nice slab, without a flatlap if you want to lap it by hand all you need is a flat piece of glass and some grit 100 grit first and then 220 from memory make a paste and move the stone in a figure 8 then you can back it and make a doublet . Bill
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itsandbits
freely admits to licking rocks
Member since March 2012
Posts: 825
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Post by itsandbits on Jul 21, 2012 22:10:33 GMT -5
cut it in half and epoxy it back to back. didn't the seller put the dimensions in the post?
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Deleted
Deleted Member
Member since January 1970
Posts: 0
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Post by Deleted on Jul 21, 2012 22:47:10 GMT -5
I make flat top cabs all the time. Even thick ones. Tougher to get the scratches out of the center but it is possible. Jim
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Post by rockjunquie on Jul 22, 2012 0:11:17 GMT -5
Thanks Yes, the seller listed a size but it was wrong. I heard of doubling the thickness before, but I was hoping to use the whole slab. It's too nice not to. I was thinking of flat tops, too, Jim. I did porno cab that way and found out what you mean about the scratches. What do you do? Round off the corners and polish? With porno cab, I did a bevel around the edge and polished because I didn't want to get into the image. But, I'd rather not do that on this.
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jason12x12
freely admits to licking rocks
Member since October 2011
Posts: 798
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Post by jason12x12 on Jul 22, 2012 2:06:10 GMT -5
the diameter needs to relate to the thickness of the cab to put a dome on a thin material. back with another material quartz or whatever... 3.5 to 4 mm is plenty thick when backed.
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Deleted
Deleted Member
Member since January 1970
Posts: 0
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Post by Deleted on Jul 22, 2012 7:43:19 GMT -5
You did it exactly the way I do it. Just round off the edges then polish. I do it because I want the thick edge so I can do a groove wrap. Jim
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Post by gingerkid on Jul 22, 2012 8:21:04 GMT -5
Hi, rockjunquie, maybe you could give the slab a nice polish and frame it? I have a few slabs (well, to be honest, a lot picture jaspers and agates with inclusions :blush: ) that I can't bring myself to cab because of their beauty. Here's 2 framed Owyhee Jasper slabs that were made by rocks2dust. I also have a beautiful framed piece of 'Bama petrified wood with citrine and smoky quartz xtls on it that he made. Sorry about my lacking photography skills. :blush: Attachments:
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Post by rockpickerforever on Jul 22, 2012 8:52:29 GMT -5
Tela, instead of backing the thin stone, how about a thick clear quartz cap on the front? Then you can cab it as usual, and not worry about the thin stone crumbling. Just a thought... Jean
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Post by phil on Jul 22, 2012 10:29:32 GMT -5
Thanks What do you do? Round off the corners and polish? With porno cab, I did a bevel around the edge and polished because I didn't want to get into the image. But, I'd rather not do that on this. Porno cab??? Please explain.
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Post by rockjunquie on Jul 22, 2012 11:47:59 GMT -5
Great suggestions It is beautiful enough to frame, but would make better cabs. I was hoping to avoid backing it. I'm going to try a cab and see how it goes- either flat or low domed. It should prove to be very hard and stable. I hadn't thought about quartz.... I'll see if I can cab it first. It does make sense that I would need a smaller cab to make a decent dome on a thin stone- thanks. Porno cab-- forum.rocktumblinghobby.com/index.cgi?board=ccabs&action=display&thread=53686
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Post by helens on Jul 23, 2012 20:03:06 GMT -5
What an interesting question! It really made me think.
My first favorite rocks were picture rocks... that's what actually got me started with the rock OBSESSION, vs just interested. Well, I don't like picture rocks all rounded, they should be flat... like a picture, so from that point on, I made all my cabs flat and not rounded.
The only time I rounded the top was if there's some kind of inner fire going on that requires a convex lens (like obsidian).... besides that, I just made everything either flat on top, or faced with an angle, so I could see any interesting side feature flat.
So this question actually gave me pause... because I never thought about it! The other reason in the back of my mind, to make a cab flat was if I wanted to either glue or embed something else in the stone, it would give me a lot of surfaces to work with later if I needed it. But rounded cabs are really more 'normal' aren't they? I can't believe that it never struck me how unusually I was shaping my cabs before, despite seeing so many rounded cabs here on display!!
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Post by Tonyterner on Jul 24, 2012 8:21:09 GMT -5
There is no reason to flat lap it unless the back is very uneven. I make doublets all the time and even on clear material I've never had to flat lap. Pick out a thinner slab to back it with and just glue together using epoxy. 3.5mm is still thick enough to make a nice dome, just be careful around the girdle that you don't dip down into the backing material. On the stinkingwater plume doublets I make the top layer of agate can get down to 1mm in thickness. Cut off a cab sized piece of that slab and go for it.
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zarguy
fully equipped rock polisher
Cedar City, Utah - rockhound heaven!
Member since December 2005
Posts: 1,791
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Post by zarguy on Jul 25, 2012 17:02:53 GMT -5
That thickness will be a challenge, but not impossible. You can do it without a backing or quartz cap. You don't have to make a flat top cab either. I often do double sided cabs from a 1/4" (6mm) slab. That's 3mm per side!
If you aren't already, I'd use a dopstick to get more control of the cab as you work up the dome.
Lynn
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Post by rockjunquie on Jul 25, 2012 18:33:58 GMT -5
I had Gene out today. I found a slab that was real thin and did some practice with it. I took awhile, but I did it-- I got a very lowdome cab. ;D This is a mystery material from Susan. I think it is an agate jasper.
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