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Post by 1dave on Jan 4, 2019 8:07:24 GMT -5
Hello, my almost-neighbor! Yes, people here are very helpful. I haven't even been a member for a week and I already learned so much! Okay then, I shall attack the stones with steel! This is a good advice for a total newbie like me. But just out of curiosity: is there also a way to polish softer stones?
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Post by fernwood on Jan 4, 2019 8:36:06 GMT -5
Steel does not break down. I have polished some softer stones, which are prone to cutting of the softer spots.
Best results were received using SIC 60/80, then 120/220 SIC and ceramics and pre-polished pea gravel (stage specific) for first 2 stages. Then more stage specific pea gravel and plastic tumbling pellets, also stage specific.
All soft rocks were combined with other soft ones. Did a 24 to 48 hour Borax cleaning between stages to remove all grit/polish from previous stages.
I do a 5 step tumbling process for soft stones. Include an AO 1200 pre-polish before the final polish.
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Kai
spending too much on rocks
Member since December 2018
Posts: 331
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Post by Kai on Jan 4, 2019 11:34:32 GMT -5
Wow, thanks 1dave ! What an honour, a thread created just for me! Thanks for the instructions fernwood . Could you please tell me a bit more about what is "pre-polished pea gravel"? Sorry, I saw your thread but I'm a total newbie and haven't yet had time to read through the forum thoroughly.
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Post by grumpybill on Jan 4, 2019 13:25:24 GMT -5
...what is "pre-polished pea gravel"? Pea gravel is the common name for small pebbles, roughly the size of a pea...give or take. Pre-polished means they've been run through all cycles of a tumbler.
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Post by rmf on Jan 4, 2019 15:40:54 GMT -5
@kia pea gravel is sold here in the US for decorative purposes and the quartz variety polishes. Also when you tumble anything less that 1/2inch (12.5mm) makes nice rounded pebbles. These can also be used as filler in the finer grinds and in polishing as they tend to cushion the larger stones.
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Kai
spending too much on rocks
Member since December 2018
Posts: 331
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Post by Kai on Jan 5, 2019 7:45:59 GMT -5
Riiight... I just found the FAQ thread where this very question is already mentioned. *feels ashamed* Can't help it, there are lots of posts on this forum and I've only been here a week... However... I may be stupid (or even more stupid than I already believe I am) but I can't see the answer in that thread? *feels even more ashamed*Is it somewhere in Tutorials where I overlooked it?
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,154
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Post by jamesp on Jan 5, 2019 9:33:06 GMT -5
If you are planning on using a tumbler to polish soft stones you might want to start with obsidian. Stones softer than obsidian are a serious challenge to polish in a tumbler. It would help to which soft stones you have in mind to tumble polish. You might get a tumble polish on basalt or rhyolite if they have a high silica content. Matte polish yes, wet shine not so easy. I have never seen anyone on this forum tumble polish calcite. I once got a tumble polish on fluorite, but it was only two stones out of about 40 pieces and have no idea why they polished: I regularly polish soft soda lime glass but had to modify a vibratory tumbler extensively to make it work. A Lot-O tumbler is a good tumbler to use for some soft stones including obsidian and glass. This is some soda lime glass with what is considered a wet polish. It was shaped first in a rotary with SiC 60, then a long run of SiC 500. Both run with colloidal clay slurry. Then polished with aluminum oxide 220 and 14,000 using the specially modified vibratory tumbler. Using sugar for a slurry thickener and a minimum of 30% by volume(afore mentioned) tumbled quartz pea gravel as media. But bear in mind I can not polish this glass without a specialized machine. Maybe some calcite or fluorite should be tossed in with the glass to see if it will polish. I just never tried.
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,154
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Post by jamesp on Jan 5, 2019 10:12:22 GMT -5
This is an early run of glass in the modified vibe using a high percentage quartz pea gravel. The right side hopper is slightly bruising the glass because it is vibrating a bit too violently. Problem was solved by reducing right side counterbalance off-balance. Coating on rocks is sugar syrup similar in consistency to warm pancake syrup. abrasive is alum ox
This run is 50 to 60% pea gravel media to break down the alum ox quickly.(100% glass will not break down alum ox in a timely fashion). Eventually 25 to 30% pea gravel/70% glass was optimum in time-to-finish and volume of targeted glass. The higher percentage of quartz pea gravel to glass the faster the alum ox breaks down and the quicker you get a polish. The role of the quartz pea gravel is to break down the alum ox. It is not needed for padding in this case. How do I know this ? Because I ran a load of polished glass pendants without media and no bruises or frosting occurred. In many cases media does protect soft materials from bruising and frosting. But not in my case because the glass was held below 25 gram pieces. Above 30 grams per unit and bruising does occur. Size matters.
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,154
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Post by jamesp on Jan 5, 2019 10:19:12 GMT -5
Conclusion
Soft materials are challenging to tumble polish.
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Post by 1dave on Jan 5, 2019 10:23:18 GMT -5
Riiight... I just found the FAQ thread where this very question is already mentioned. *feels ashamed* Can't help it, there are lots of posts on this forum and I've only been here a week... However... I may be stupid (or even more stupid than I already believe I am) but I can't see the answer in that thread? *feels even more ashamed*Is it somewhere in Tutorials where I overlooked it? I have seven daughters and have answered billions of "WHY?'s." The only stupid questions are those not asked. A warning:
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,154
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Post by jamesp on Jan 5, 2019 10:52:29 GMT -5
I just had a couple of steel prototype vibratory tumblers hauled off recently 1dave. All failures he he. Each failure got closer and closer to success. Direction established and am up and running. Might make another good motto "Each failure takes you closer to success". Maybe, not necessarily true all the time. Depends on persistence.... And trashed a bunch of PVC tumbler barrels that did a great job with siC 30-46 but wore out too fast when using SiC 4-8-16. The HPDE barrels are now the barrel of choice when high speed coarse grinding with these aggressive abrasives. HDPE famous for pumping abrasive mine slurries. Tough barrels. You can even park a car on top of one of them. Making HDPE barrels out of SDR 11 or SDR 17 pipe fittings: www.flickr.com/photos/67205364@N06/sets/72157673297787998
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Kai
spending too much on rocks
Member since December 2018
Posts: 331
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Post by Kai on Jan 5, 2019 13:22:31 GMT -5
jamesp : wow, thanks! That was detailed! Maybe this is still one step too far, i'm not quite up for such complexity yet. Okay, I guess I'll stay just with harder stones for a while... But thanks anyway for your effort, I'll definitely remember this and will come back here to look for the instructions when I need them. 1dave : whoops, okay! Warning acknowledged! (probably won't be heeded in the future, though...) :-P
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,154
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Post by jamesp on Jan 5, 2019 21:49:55 GMT -5
jamesp : wow, thanks! That was detailed! Maybe this is still one step too far, i'm not quite up for such complexity yet. Okay, I guess I'll stay just with harder stones for a while... But thanks anyway for your effort, I'll definitely remember this and will come back here to look for the instructions when I need them. 1dave : whoops, okay! Warning acknowledged! (probably won't be heeded in the future, though...) :-P You might enjoy starting out with easier stones. Highly recommended. They are a challenge in themselves.
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Bucknutty
starting to spend too much on rocks
Member since November 2017
Posts: 171
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Post by Bucknutty on Jan 7, 2019 23:08:07 GMT -5
I've had decent luck with marble. These have been sitting in a jar for over a year with some harder rocks, so they've lost some of the shine, but they came out of the tumbler pretty nice. Skipped the coarse and did 2 days each 220/600/polish. You loose a LOT of material with the 220, so you have to fill in with something before the next stage, but it's solid, so there are hardly any cracks or pits, which is more than I can say for any of the harder stuff I've tried. I've got another batch in right now (ran out of coarse grit, so I needed to kill a few days on something that didn't need it until the grit arrives)
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