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Post by rockjunquie on Apr 19, 2019 16:15:47 GMT -5
OK I'll chime in. I have cut literally thousands of cabs and my first one was good enough to sell (I regret selling it to this day). Mind you it was not a good cab by my standards now but it had a decent polish. That said, most of the time the rough dictates the thickness and shape. However, I am of the opinion a cab that is about 5mm thick is ideal. Yet if I have thin tough material Thinner is possible. I have cut Brazilian agate to 2.5mm thick because the material was nice. I have been cutting since 1972 and see no reason to polish the back on most stones unless there is a need. I consider it a waste of my time for something that will never be seen (of course with wire wrap that is different now). For stones like Rutilated Quartz you need to somewhat polish the back to let the light do its best with the Rutile. I polish the backs of all Opals, Tourmaline and anything that is transparent. For material that is thicker and has a great pattern I cut double cabs. Domed on both the front and back and come to a sharp edge at the girdle. What I call a buff top cab has a low dome and angled sides. I have never measured the angle. For many years I did not angle the bottom because the mounts I was cutting for did not require it. Now all stones get either a chamfer (more or less 45 deg) or round with a 325grit diamond wheel. This reduces the stress on the cab while it is being set (reducing chipping). For buff top cabs I also round or chamfer the sharp edge where the dome transitions to the girdle. This keeps the top from chipping. As for flat spots MsAli we all get them and for me it is due to being too impatient. I also found a cab I "finished" I have to redop to take out some lines I did not notice while it was wet. When I started cutting there were only domed cabs none of this straight sides or angled girdle and low dome tops. This technique came about because of diamond wheels which allow a cutter to cut low angles and get good doming all the way across the stone. Not that these buff tops were not done with SiC wheels but they were much harder to do. Also a dome from with a nice curve from back to the top of the stone removes more material than the low dome buff top cabs so diamond has allowed cutters to speed up cutting and be more creative. For the last 40+ years I have cut mostly replacement stones for local jewelers (unfortunately most is Black Onyx). Thank you for your post! Very thoughtful. I didn't see it when I posted above and I notice we agreed on a few things. I didn't know about the change in cabbing with the advent of the genie type machines. Interesting. |
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Post by rockjunquie on Apr 19, 2019 16:18:06 GMT -5
I know everyone who cabs is way ahead of me but I did have a question. How do you know when to give up on a stone? I've been working on this one for a couple of hours and I really like it. It looks way better in person but there's soft spots, pits and cracks. How do you know if it's worth going deeper or do you just take your chances? Plus, throw in the fact that I have probably 100's of other stones I could work on with just as much or more potential. Anyway, here's what it looks like right now. Thanks.  Mike, I think if you like it, then it is worth your time. BUT, if I was selling it, I would quit at the point where I am losing money. I have put a lot of time into cabs that should have been tossed, but sometimes, I just like the challenge and I want to see what it looks like finished. For you, I would also say it is a learning experience. |
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Post by miket on Apr 19, 2019 16:40:20 GMT -5
I know everyone who cabs is way ahead of me but I did have a question. How do you know when to give up on a stone? I've been working on this one for a couple of hours and I really like it. It looks way better in person but there's soft spots, pits and cracks. How do you know if it's worth going deeper or do you just take your chances? Plus, throw in the fact that I have probably 100's of other stones I could work on with just as much or more potential. Anyway, here's what it looks like right now. Thanks. Mike, I think if you like it, then it is worth your time. BUT, if I was selling it, I would quit at the point where I am losing money. I have put a lot of time into cabs that should have been tossed, but sometimes, I just like the challenge and I want to see what it looks like finished. For you, I would also say it is a learning experience.  To everything you said. I like the challenge, I like the stone and it is indeed a learning experience. Maybe IF I ever get to the point of selling then I'll change my views but for now this is just a hobby that I'm really enjoying. Probably a little too much...  Thank you. |
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Post by Rockindad on Apr 19, 2019 16:41:41 GMT -5
Okay, here is a question I have wondered about. Please no one take offense by how this is worded. Are there any "real" cab makers (as in actually using a cabbing machine) who finish their cabs in a vibratory tumbler to have polished backs? Yes I am aware that some people shape the stones via other methods and use a vibe to finish, so just responses to the above please. Thanks, Al This is not the first time I have heard that a vibratory tumbler could be used to polish the backs, Al. I think it sounds pretty obvious actually. Spend 5-10 minutes using any one of the aforementioned techniques above to get the back to around 500 Then toss it in the Vibe with a ton (50%-70%) of your favorite ceramic media to Polish. It could work. To be honest I do not think it is all that obvious. The tumbler is a much rougher and indiscriminate machine than a cabbing machine. With the work I see being done by many on here I am not sure how many would be willing to throw them in a tumbler after spending so much effort on the face/dome, girdle, etc. Even though it would be a polish stage the whole cab will be subject to the action in the tumbler, not just the back. Al |
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Post by rockjunquie on Apr 19, 2019 16:49:30 GMT -5
This is not the first time I have heard that a vibratory tumbler could be used to polish the backs, Al. I think it sounds pretty obvious actually. Spend 5-10 minutes using any one of the aforementioned techniques above to get the back to around 500 Then toss it in the Vibe with a ton (50%-70%) of your favorite ceramic media to Polish. It could work. To be honest I do not think it is all that obvious. The tumbler is a much rougher and indiscriminate machine than a cabbing machine. With the work I see being done by many on here I am not sure how many would be willing to throw them in a tumbler after spending so much effort on the face/dome, girdle, etc. Even though it would be a polish stage the whole cab will be subject to the action in the tumbler, not just the back. Al Maybe we can get someone to do an experiment. I have never tumbled, but my understanding is that doing a polish with the vibe will not round the edges. Is that true? |
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Post by Rockindad on Apr 19, 2019 16:56:00 GMT -5
To be honest I do not think it is all that obvious. The tumbler is a much rougher and indiscriminate machine than a cabbing machine. With the work I see being done by many on here I am not sure how many would be willing to throw them in a tumbler after spending so much effort on the face/dome, girdle, etc. Even though it would be a polish stage the whole cab will be subject to the action in the tumbler, not just the back. Al Maybe we can get someone to do an experiment. I have never tumbled, but my understanding is that doing a polish with the vibe will not round the edges. Is that true? Depends at what grit/polish you put them in. At 220 you will definitely lose material. 500 maybe. 1000 or higher no, but you will probably be going backwards depending on how far you worked it on the cabbing machine. Al |
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Post by rockjunquie on Apr 19, 2019 16:58:01 GMT -5
Maybe we can get someone to do an experiment. I have never tumbled, but my understanding is that doing a polish with the vibe will not round the edges. Is that true? Depends at what grit/polish you put them in. At 220 you will definitely lose material. 500 maybe. 1000 or higher no, but you will probably be going backwards depending on how far you worked it on the cabbing machine. Al Oh yeah, duh. I hadn't thought about that. If I polish a cab to 50 or 100k, it wouldn't do any good to throw it in the tumbler. |
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Post by Rockindad on Apr 19, 2019 17:03:38 GMT -5
Depends at what grit/polish you put them in. At 220 you will definitely lose material. 500 maybe. 1000 or higher no, but you will probably be going backwards depending on how far you worked it on the cabbing machine. Al Oh yeah, duh. I hadn't thought about that. If I polish a cab to 50 or 100k, it wouldn't do any good to throw it in the tumbler. Yeah that's what I'm getting at- how many are willing to throw their cabs with the faces finished in a vibe just to get the back. Maybe take the cab so far on the machine, go to the vibe for the backs and then finish the face on the machine? I think this might make sense for volume work or people that sell a certain amount. Probably not for those that just do a few here and there. Al |
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NevadaBill
fully equipped rock polisher
Member since January 2019
Posts: 1,332
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Post by NevadaBill on Apr 19, 2019 17:17:06 GMT -5
To be honest I do not think it is all that obvious. The tumbler is a much rougher and indiscriminate machine than a cabbing machine. With the work I see being done by many on here I am not sure how many would be willing to throw them in a tumbler after spending so much effort on the face/dome, girdle, etc. Even though it would be a polish stage the whole cab will be subject to the action in the tumbler, not just the back. Al Maybe we can get someone to do an experiment. I have never tumbled, but my understanding is that doing a polish with the vibe will not round the edges. Is that true? Tumbling, my biggest worry would be rounding the sides. I wouldn't want to alter the diameter much. In my limited experience with tumbling, I have not found the Rock Shed polish (14,400 grit for reference) to remove any material at all really. But I haven't really used a micrometer to measure (before / after), so I can't actually back this statement up. Then again, I am using very little (like 1/2 a TSP polish, mixed with Borax), with a +/- 3 lb. load of rocks + media. I can't say for something coarse such as 1200 AO. I just don't have enough experience with it. Once I get in to cabbing, this will be tested and some day maybe I'll do a write up. |
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romo
starting to spend too much on rocks
Member since September 2018
Posts: 104
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Post by romo on Apr 19, 2019 21:32:23 GMT -5
You can rotary tumble a cab but the edges will round out leaving more of a palm stone (to me) than a cab. Did this one in my QT66.   |
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Post by miket on Apr 19, 2019 22:13:26 GMT -5
I see what you mean.
I still think I'm going to try, I don't really have a choice quite yet.
When I do have a cabber I may have to go back to them and fix them.
But at least it should go fast!
😀
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romo
starting to spend too much on rocks
Member since September 2018
Posts: 104
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Post by romo on Apr 19, 2019 23:41:41 GMT -5
I see what you mean. I still think I'm going to try, I don't really have a choice quite yet. When I do have a cabber I may have to go back to them and fix them. But at least it should go fast! 😀 You should definitely keep at it! |
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Post by hummingbirdstones on Apr 19, 2019 23:50:47 GMT -5
Depends at what grit/polish you put them in. At 220 you will definitely lose material. 500 maybe. 1000 or higher no, but you will probably be going backwards depending on how far you worked it on the cabbing machine. Al Oh yeah, duh. I hadn't thought about that. If I polish a cab to 50 or 100k, it wouldn't do any good to throw it in the tumbler. I'm going to 'fess up to putting my cabs in a vibe tumbler with 50K Vibra Dry in it sometimes. I had a cab that just wouldn't polish to the extent I wanted (I'm really picky with my polish), so I threw it in the Vibe (it's just a reloader vibe I bought for jewelry) and I'll be damned if it didn't polish up as pretty as you please. Everything I've put in there since has come out better than when I put it in. Even some hard porcelain jaspers or agates look better somehow when I take them out. I don't know why. I've put some in just for giggles to see if it made a difference and it always looks like it does. Just an hour or so and then I take them out. Doesn't round the stone or take material off.
I don't think I'd put them in a rotary tumbler or vibe with ceramics or whatever you would use. I'm not that brave.
The only time I ever tumbled a stone from start to finish was when I was a kid and my mom got me one of those toy tumblers for Christmas one year.
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Post by rockjunquie on Apr 20, 2019 7:23:50 GMT -5
Oh yeah, duh. I hadn't thought about that. If I polish a cab to 50 or 100k, it wouldn't do any good to throw it in the tumbler. I'm going to 'fess up to putting my cabs in a vibe tumbler with 50K Vibra Dry in it sometimes. I had a cab that just wouldn't polish to the extent I wanted (I'm really picky with my polish), so I threw it in the Vibe (it's just a reloader vibe I bought for jewelry) and I'll be damned if it didn't polish up as pretty as you please. Everything I've put in there since has come out better than when I put it in. Even some hard porcelain jaspers or agates look better somehow when I take them out. I don't know why. I've put some in just for giggles to see if it made a difference and it always looks like it does. Just an hour or so and then I take them out. Doesn't round the stone or take material off.
I don't think I'd put them in a rotary tumbler or vibe with ceramics or whatever you would use. I'm not that brave.
The only time I ever tumbled a stone from start to finish was when I was a kid and my mom got me one of those toy tumblers for Christmas one year.
Good to know! Is this what you have? www.brownells.com/reloading/case-cleaning/case-tumblers-accessories/thumler-s-ultra-vibe-vibratory-tumblers-prod54712.aspx What is vibra dry? |
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Post by hummingbirdstones on Apr 20, 2019 10:45:38 GMT -5
I was using it for metal. Does a great job taking tarnish off of silver jewelry. I use the 50K grit.
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Tommy
Administrator 
Member since January 2013
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Post by Tommy on Apr 20, 2019 11:13:49 GMT -5
I tumble mostly flats for giveaways and have found that finishing by tumbler can be very problematic with variable hardness materials which describes most of what I work with for selling, not because of rounding corners but undercutting. The problem is the same as when creating a cab on wheels - the higher grits 600/1000/polish are not removing any hard material but can still remove the softer areas. In other words, I have observed that the worst undercutting occurs at the higher grits - and thus probably 90% of anything I would cab for sales is automatically eliminated from being able to finish in the tumbler.
The only type of stone I would even attempt to finish to "hand made cabochon" quality in a tumbler would be solid (clear) agate with no imperfections that reach the surface - Montana agate comes to mind.
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Post by stardiamond on Apr 20, 2019 11:31:29 GMT -5
I picked up two lots of tumbled Owyhee cabs some years ago at a very low price. About 10 pieces were thick enough, large enough and had nice scenes to recut as cabs. The rest I put in the box pictured. I had these briefly in the trade forum, but my wife wanted to keep them. I assume that the person cut up some slabs with a trim saw and tumbled them. What I noticed was that they had a very nice polish. Most became very thin with heavily rounded corners and edges.  |
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Post by rmf on Apr 21, 2019 10:24:35 GMT -5
rockjunquie When to give up on a stone. That is a good question. After so many years cabbing I still don't know a good answer to that question. What I tend to do is cut till frustrated then set it aside and cut something else. Some times you run up on a new idea to help your self. some times it is a flat spot in the center you just can't get out. Sometimes I just set it aside leave it on the dop then come back (yes even up to a year later) and the "mood" will hit me and for what ever reason I have new inspiration and it just suddenly works. I had a piece of Bots that I had up stairs by where I sit when I watch TV. It had two sides one slightly better than the other and some nicks and chips. I fondled that slabette and fumbled it and looked at it for 9 months and I know my wife was glad when I finally took it downstairs and cut it. When it came out it was perfect. Sometimes you just have to be in the right mood to finish a stone especially a difficult stone. I hate redoping so I tend to leave them on the dop until I am ready to try again. I do have a jeweler friend that said all stones are not meant to be cut and I try to keep that in mind. We always cut more mediocre stones than spectacular ones. I still hate to work on something and it be a total waste of time. That is partly why I hate working Jade. It is so variable. Some pieces polish great and some will never polish to my liking even with diamond.
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Post by rockjunquie on Apr 21, 2019 10:31:55 GMT -5
rockjunquie When to give up on a stone. That is a good question. After so many years cabbing I still don't know a good answer to that question. What I tend to do is cut till frustrated then set it aside and cut something else. Some times you run up on a new idea to help your self. some times it is a flat spot in the center you just can't get out. Sometimes I just set it aside leave it on the dop then come back (yes even up to a year later) and the "mood" will hit me and for what ever reason I have new inspiration and it just suddenly works. I had a piece of Bots that I had up stairs by where I sit when I watch TV. It had two sides one slightly better than the other and some nicks and chips. I fondled that slabette and fumbled it and looked at it for 9 months and I know my wife was glad when I finally took it downstairs and cut it. When it came out it was perfect. Sometimes you just have to be in the right mood to finish a stone especially a difficult stone. I hate redoping so I tend to leave them on the dop until I am ready to try again. I do have a jeweler friend that said all stones are not meant to be cut and I try to keep that in mind. We always cut more mediocre stones than spectacular ones. I still hate to work on something and it be a total waste of time. That is partly why I hate working Jade. It is so variable. Some pieces polish great and some will never polish to my liking even with diamond. I completely understand. I could have written that myself. I just did a blog on a slab I put away for 6 years! I didn't want to get it wrong. After it shattered, I wanted to give up, but I didn't. |
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NevadaBill
fully equipped rock polisher
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Post by NevadaBill on Apr 23, 2019 18:51:18 GMT -5
This is turning into a great topic. I am already learning a lot. Thank you rockjunquie for starting it. New to cabbing (again), I am going to be returning to this thread often for tips and tricks. I hope that others who drop by less frequently will see it also, and contribute what they can. |
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To everything you said. I like the challenge, I like the stone and it is indeed a learning experience.
