richardh
spending too much on rocks
Member since June 2016
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Post by richardh on Sept 7, 2016 22:54:57 GMT -5
I was making a fuss a few weeks ago about some photos here of some Mexican Crazy Lace Agate and a friend surprised me with two pounds of it from Kingsley North. I assume the quality of the rough is good as Kingsley North seems to have quite a good reputation here.
I started out using the tile saw to cut the pieces of stone to shapes I thought would tumble well then I started running them with large ceramic media and 46-70 grit SiC in my HF rotary tumbler. After a week I checked the material and noticed that pretty much all of the pieces had started undercutting.
I was a little concerned but I figured one week wasn't much tumble time so I started them again, this time with some 30 grit SiC also purchased by my friend from Kingsley North.
It has been running for two more weeks with two clean outs with the SiC 30. I have noticed that the SiC 30 has pretty well broken down after a week so it looks like I am getting good efficiency in the tumbler. The problem is that the undercutting is getting worse and worse with time, not better.
Is undercutting just a normal challenge with Mexican Crazy Lace?
Any help is appreciated.
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Post by Garage Rocker on Sept 8, 2016 7:55:55 GMT -5
I find Crazy Lace and Ocean Jasper a little frustrating to tumble. I like to see a nice flawless rock move on to stage two, but I don't really get that with those materials. I've had some pieces come out without fractures and/or pits, but more often I just get tired of tumbling them and pass them along and hope for the best. There is some of each in this batch, if you want to see what my results looked like. forum.rocktumblinghobby.com/thread/75454/june-tumbles-pic-heavy?page=1Post a pic of what you're seeing at your next clean out.
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Post by roy on Sept 8, 2016 10:32:41 GMT -5
no expert on tumbling but i would think that you would want to start with 180 grit these rocks have lots of soft areas
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Post by Garage Rocker on Sept 8, 2016 10:40:08 GMT -5
no expert on tumbling but i would think that you would want to start with 180 grit these rocks have lots of soft areas That makes sense, I usually start crazy lace in 60/90 and tumble in the small barrel with media. Takes a while to round them out that way.
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jamesp
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Post by jamesp on Sept 8, 2016 11:52:33 GMT -5
If a stone is under cutting it about has to have soft areas in it. That would be gaurenteed if the under cutting happens on a particular band/stipe/spot or other anomaly.
I received a brick sized chunk of crazy lace and removed well silicified portions of it for tumbling. Sections of that block were more attractive but had crusty or ill formed bands in those areas. Even after tumbling what looked like the most solid material some of the bands had a poor polish suggesting different hardnesses.
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Post by orrum on Sept 8, 2016 12:18:21 GMT -5
My personal luck tumbling had me abandon the use of 46/70 grit and go back to 60/90. Just seemed like I got betterm results. Not as fast but better. Remember I tumble everything together of mixed Mohs so maybe that's it. Good luck, I love crazy lace!
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richardh
spending too much on rocks
Member since June 2016
Posts: 391
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Post by richardh on Sept 8, 2016 12:24:54 GMT -5
Thanks for the feedback. Yes the undercutting is happening in specific bands. I thought I was done purchasing grit for a while but maybe I do need to get some 60-90 and give it a try.
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Post by Garage Rocker on Sept 8, 2016 12:45:40 GMT -5
I use 60/90 in my small barrels. 4 tablespoons each, changed out every 7-10 days. 5 lbs. of 60/90 will last me a while. But yes, an assortment of grit sizes.
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Sabre52
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Post by Sabre52 on Sept 8, 2016 12:47:30 GMT -5
I may not be remembering this right, but I believe crazy lace agate originates as veins in a limestone deposit. This may account for the calcite/aragonite crystals sometimes seen in it, along with quartz crystals and the differences in the amounts of silica/hardness in the different layers which can result in undercutting.....Mel
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jamesp
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Post by jamesp on Sept 9, 2016 12:34:48 GMT -5
I may not be remembering this right, but I believe crazy lace agate originates as veins in a limestone deposit. This may account for the calcite/aragonite crystals sometimes seen in it, along with quartz crystals and the differences in the amounts of silica/hardness in the different layers which can result in undercutting.....Mel This must be what happens.
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jamesp
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Post by jamesp on Sept 9, 2016 12:38:31 GMT -5
I looked back on my crazy lace procedure. I brutalized it with SiC 30, ran last 30 grit add for two weeks to get complete breakdown.. Then straight to vibe w/AO 500 to a polish. Nary a bit of undercutting BUT this was some darn hard crazy lace. rockpickerforever thanks
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Post by rockpickerforever on Sept 9, 2016 15:48:39 GMT -5
I already said it, but you are welcome You don't have to keep on thanking me for eternity, lol.
I'm glad you were able to put such a fine shine on them!
Jean
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jamesp
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Post by jamesp on Sept 9, 2016 19:44:43 GMT -5
I already said it, but you are welcome You don't have to keep on thanking me for eternity, lol.
I'm glad you were able to put such a fine shine on them!
Jean Reminds me of crazy lace in tumbled when I was 13 years old. Crazy lace was popular in 1970. Maybe a psychedelic thing.
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jamesp
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Post by jamesp on Sept 9, 2016 20:01:17 GMT -5
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richardh
spending too much on rocks
Member since June 2016
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Post by richardh on Sept 10, 2016 17:06:11 GMT -5
Wow those came out great. When it's time for my next clean out I will take a couple of photos to share.
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jamesp
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Post by jamesp on Sept 10, 2016 17:46:52 GMT -5
Wow those came out great. When it's time for my next clean out I will take a couple of photos to share. By all means. Crazy lace are eye candy.
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Post by krazydiamond on Sept 10, 2016 19:14:23 GMT -5
There are variations in the quality of some material called "Crazy Lace". I've seen some really good material and some with a lot of the soft stuff you seem to have. Even Kingsley North can ship some pretty mediocre stuff on occasion. Having said that, i also use 60/90 as my first coarse run, and sometime run that for a month to achieve to acceptable shape.
KD
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jamesp
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Post by jamesp on Sept 11, 2016 4:10:15 GMT -5
There are variations in the quality of some material called "Crazy Lace". I've seen some really good material and some with a lot of the soft stuff you seem to have. Even Kingsley North can ship some pretty mediocre stuff on occasion. Having said that, i also use 60/90 as my first coarse run, and sometime run that for a month to achieve to acceptable shape. KD Difficult to break crazy lace with a hammer. Too many fractures along the crazy seam lines. I gave up and saw and pre-shape.
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metalsmith
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Post by metalsmith on Sept 11, 2016 5:17:08 GMT -5
Reminds me of crazy lace in tumbled when I was 13 years old. Crazy lace was popular in 1970. Maybe a psychedelic thing. It must be speaking to me subliminally ... I love it! Great work on that.
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jamesp
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Post by jamesp on Sept 11, 2016 6:57:33 GMT -5
Reminds me of crazy lace in tumbled when I was 13 years old. Crazy lace was popular in 1970. Maybe a psychedelic thing. It must be speaking to me subliminally ... I love it! Great work on that. Crazy lace is like no other metalsmith.
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