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Post by nowyo on Feb 19, 2018 2:00:14 GMT -5
Great batch, and some interesting info in the thread.
Russ
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,179
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Post by jamesp on Feb 19, 2018 6:58:34 GMT -5
Love those bots. You got some really interesting ones in there. I was really frustrated with the impact marks on mine too but they really don't show up nearly as bad to the human eye. I assumed they were caused in stage one rotary because I still got them when running stage 2-5 in the lot-o with a very gentle 50% ceramic filled load. If the lot-o is not damaging obsidian at 50% ceramic it should not be damaging agates right? Were these bots from the rock shed or the gem shop? Chuck Those half moons are sure nuff impact marks. Wrestled with them many times learning to tumble big rocks. #1 solution was to tumble big rock with 100% smaller rocks in a smaller barrel with 85% fill; yes the clay helps but it is risky depending on the clay slurry to protect you rocks. Maybe Chuck can shed some light on this trick. Chuck, did you mention running your rocks in the rotary with water covering the rocks ? I recently started running high water in big 8 inch/25 pound harder poly barrels with glass at a whopping 63 RPM. That is a very fast speed for such a big barrel. With out clay and with 85% or higher barrel fill. The sound - the rattling went away. It now makes a low grumble and no chattering or rattling sounds because the glass is underwater. It may slow the grind time, but not by much. (Glass unlike agate does grind fast so a non-issue). I now have thin glass shards surviving 25 pounds of glass at 63 RPM. If the water in the barrel was lower and it was rattling these would have been broken. The problem is Botswana agate. Those Bots must be the most delicate agate on Mother Earth. Don't you run 3 and 6 pound barrels Rob ? Small rocks in the 1 to 2 inch category ? Long thin glass less than 1/16" thick. 29 carats/6 grams
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,179
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Post by jamesp on Feb 19, 2018 7:08:32 GMT -5
You can use a couple of microscope glass slides for a tester. Put a couple in the rotary and keep it in the barrel throughout the rotary runs. If it does not break then you are likely running a gentle enough tumble to avoid impact bruises.
Never seen an agate bruise that easy. Totally freaky. No big deal, bet you can't see them w/naked eye.
Rob, you could take that bruised one and tap on it with say the end of a screw driver to see how easy it is to make impact marks.
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Post by Jugglerguy on Feb 19, 2018 7:12:15 GMT -5
Yes, in this case the rocks were run in a 6 lb. barrel. I do sometimes run larger rocks, but I don't think there would have been anything larger than a two inch rock in with these.
I like your idea of running in a smaller, overfilled barrel with extra water.
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,179
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Post by jamesp on Feb 19, 2018 8:28:39 GMT -5
Yes, in this case the rocks were run in a 6 lb. barrel. I do sometimes run larger rocks, but I don't think there would have been anything larger than a two inch rock in with these. I like your idea of running in a smaller, overfilled barrel with extra water. I am not certain but it seemed Chuck recently mentioned the high water thing.
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Post by aDave on Feb 19, 2018 14:02:42 GMT -5
Nice stuff Rob Jugglerguy . Too many to pick a fave, as there are alot to choose from. Seeing your work tells me I have to break down and run some more. I think I have about 3-4 pounds left. FWIW, I've had good luck with Bots from rocktumbler.com. They were out for a while, but they've gotten more.
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Post by Jugglerguy on Feb 19, 2018 16:33:14 GMT -5
Nice stuff Rob Jugglerguy . Too many to pick a fave, as there are alot to choose from. Seeing your work tells me I have to break down and run some more. I think I have about 3-4 pounds left. FWIW, I've had good luck with Bots from rocktumbler.com. They were out for a while, but they've gotten more. Actually, that's where I bought them. Drummond Island Rocks, I bought from rocktumbler.com, not The Gem Shop. I'm glad you said something, Dave.
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Post by txrockhunter on Feb 20, 2018 23:34:16 GMT -5
Great batch, Rob! Gotta say 7, 24, & 30 are the favorites. Don't have much experience with bots, but I've had similar impact marks when tumbling some of the Marfa agates. Never thought about agate being soft.
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ingawh
starting to spend too much on rocks
The rock wants to shine, I just help it get there
Member since February 2011
Posts: 194
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Post by ingawh on Feb 21, 2018 1:37:59 GMT -5
I get those crescent fractures when i turmble larger stones without enough smalls to act as filler. Echoing Rodeodan's thought... Filler stones to cushion. (I use small, 7-mohs stones that I've already polished, but you can also get ceramic media.) Gorgeous stones - thanks for the great photos!
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illusionist
starting to spend too much on rocks
Member since August 2017
Posts: 137
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Post by illusionist on Feb 21, 2018 11:07:03 GMT -5
Beautiful stones!
Bots are always worth the long stage one time!
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tkvancil
fully equipped rock polisher
Member since September 2011
Posts: 1,546
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Post by tkvancil on Feb 26, 2018 11:46:03 GMT -5
I would normally agree about them coming from rolling in the river but I got them on a bunch of my cut faces on the ones I did. All of my tumbles were nodules I cut in half so I would not expect river impacts in the middle of 2"-3" nodules. I chalked them up to the abuse of 3-4 months of rising and falling in stage one. I never use any fillers in stage one but I think that it would have helped with my bots. I could tell by the sound that by the end of each week they were taking a beating. A full batch of mohs 7 agates does not create a very good slurry. After 6 years tumbling still keeps me on my toes. Chuck That’s pretty good evidence for the tumbler causing the damage. Maybe some of Jame’s clay would be useful with Bots. Has anyone seen these crescent shaped marks on other types of rocks? I think I’ve only seen them on Botswana agates. I have seen these in almost any agate that is semi-translucent to translucent. I'm about as sure as I can be that they occur in the rotary and get "highlighted" once a shine is on. They are hard to spot before then. Often they can only be seen from one aspect. Rotate the rock and they go from seen to unseen. Add the rougher finish from coarse grind and they can go unnoticed quite easily. I have a tumbled slab of Montana that has a ton of crescents on one face but few on the other. Still can't figure that one out. I have been able to see some of these crescents in a few pieces of crushed rough. So hard to see when the surface is rough though. At least as far as I can tell the larger the rock the more likely they are to occur. The batch of Montanas had crescents in most of the larger rocks. The one inch and less were much less affected. At this point I'm accepting them begrudgingly as "part of the process" until a solid answer comes along.
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