jamesp
Cave Dweller 
Member since October 2012
Posts: 36,607
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Post by jamesp on Dec 15, 2014 10:17:15 GMT -5
James I'm sure you'll get a great shine on obsidian but it's sometimes good to walk away from something that's frustrating and do something you know will come out great! connrock Many work 9 to 5, a tumbler's work is never done  You bet there is obsidian rolling as we speak. Not going to take a whipping that easy. Tumbling too slow a process, I'm getting old, don't want the grand kids having to figure it out. Here's where it stands: 6 days AO 46 6 days AO 220 3 days into AO 500, probably 2 days more And all looks good. I took your advise about not using sugar and upping the amount of filler percentage. This time the edges are smoothing first like a normal tumble, and the flat areas last, opposite of the overly full barrel. I like your 50% filler method. It is about the only way to prevent bruising and allow the grit to break down in a rotary. Thick sugar was not letting the grit break down well either. So back to a conventional tumble. Except using glass for the filler. Funny thing about the glass filler. You can not let the barrel sit long in 46 or 220 after 3-4 days or a concretion will occur. The glass filler and the obsidian are grinding away and a lot of silt forms. That silt sets up in a hurry. No problem in 500 and finer, as there is little silt. A good reason for using ceramic, since it does not wear and add silt. Nor does it shrink and allow your rocks to get bruised. Which is how I bruised these the first time. This time glass was added to maintain filler percentage during 46 and 220 when it was shrinking so fast. I just took a sample out of the obsidian barrel this morning after typing the above. Found a dozen large obsidians piled up with no filler at the top of the barrel beating each other. The home made barrel is 6 inches X 24 inches, so a long skinny barrel. The 2 to the right were pulled yesterday, they look great. The bruised one is from this morning on left. One thing after another w/this obsidian. Long barrels not so good for rocks that require filler due to poor mixing. Getting smarter slowly.  |
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Post by connrock on Dec 16, 2014 9:15:37 GMT -5
James I'm sure you'll get a great shine on obsidian but it's sometimes good to walk away from something that's frustrating and do something you know will come out great! connrock Many work 9 to 5, a tumbler's work is never done You bet there is obsidian rolling as we speak. Not going to take a whipping that easy. Tumbling too slow a process, I'm getting old, don't want the grand kids having to figure it out. Here's where it stands: 6 days AO 46 6 days AO 220 3 days into AO 500, probably 2 days more And all looks good. I took your advise about not using sugar and upping the amount of filler percentage. This time the edges are smoothing first like a normal tumble, and the flat areas last, opposite of the overly full barrel. I like your 50% filler method. It is about the only way to prevent bruising and allow the grit to break down in a rotary. Thick sugar was not letting the grit break down well either. So back to a conventional tumble. Except using glass for the filler. Funny thing about the glass filler. You can not let the barrel sit long in 46 or 220 after 3-4 days or a concretion will occur. The glass filler and the obsidian are grinding away and a lot of silt forms. That silt sets up in a hurry. No problem in 500 and finer, as there is little silt. A good reason for using ceramic, since it does not wear and add silt. Nor does it shrink and allow your rocks to get bruised. Which is how I bruised these the first time. This time glass was added to maintain filler percentage during 46 and 220 when it was shrinking so fast. I just took a sample out of the obsidian barrel this morning after typing the above. Found a dozen large obsidians piled up with no filler at the top of the barrel beating each other. The home made barrel is 6 inches X 24 inches, so a long skinny barrel. The 2 to the right were pulled yesterday, they look great. The bruised one is from this morning on left. One thing after another w/this obsidian. Long barrels not so good for rocks that require filler due to poor mixing. Getting smarter slowly. I've never had the rocks/filler separate so you may be right about the long narrow barrels! The 2 on the right look perfect though! I hope some of the newbies are following your threads/posts cuz they can see what "patience" really means and is,,,,especially with captbob chewin at your butt! LOL Good luck,,, connrock |
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Post by captbob on Dec 16, 2014 10:30:53 GMT -5
No sugar ?!?  The sugar prices will plummet! The jobs that will be lost! My US Sugar stock wi.... < running to check >  My portfolio! RUINED!! Good thing I also invested in Gold & Silver! They what? They did? How much?? ooooooh.............. *sob* I've always had a problem with the idea of PVC barrels, but they seem to work quite well for you - for the most part. I'm sure that the pre-grinding helps. How long would it take for an agate or jasper (anything harder) to round in the PVC without a stint on the grinder? The above run of: 6 days AO 46 6 days AO 220 3 days into AO 500, probably 2 days more Was that from rough or using already tumbled rocks? If already tumbled, was the 6 days in 46 grit for removing bruises? I did an obsidian cleanout yesterday. Culled more to put in the 120/220 pile and set the barrel for another 60/90 run. The 60/90 group is close, but I started from very rough material, so there are still some crevices and previously deeper cracks that need to be perfected before moving on. Started late September, and should be ready by the end of the month to move on to 120/220. Could probably go straight from 60/90 to 500, but why rush things. Have had foamy barrels / grit very broken down on each cleanout. My question is, where are the bruises? I went back through your threads James to see what you were talking about, and know what I am looking for... but no bruises. I wonder if others running obsidian get bruises? Most folks probably don't tumble rocks this big, so that would probably lessen "bruises". I'm running the 60/90 with ceramic filler as I have no smalls in the load. Ceramic filler does wear down BTW. No plastic pellets. Will add them for grits past 60/90. Three months seems like a long coarse grit run for a "soft" stone, but I didn't do any preshaping like I normally do. And, this is a batch of pretty large rocks for a 15 pound barrel. I'll say again that rock tumbling is a poor choice of hobbies for a perfectionist! Good thing I don't give a rat's butt about how long it takes. I just want my barrels freed up for more interesting rocks. The obsidian I am tumbling is boring as heck!! Been buying a ton of Stone Canyon jasper on eBay. Looking forward to that tumble! Color!! whooo hoooo! (will pre-shape) Do have two 15 pound barrels of Dallasite from bcrockhound running. That stuff is turning out quite nicely. Not a colorful rock, but I love the brecciated patterns and I'm excited to see it finished. Will post a Dallasite thread when appropriate. Everyone should get a box of this stuff to work on! Gotta go feed the lizard - |
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,607
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Post by jamesp on Dec 16, 2014 11:14:59 GMT -5
I finally figured out where the bruises are coming from. The long barrels separating the obsidian from the filler and beating themselves.
I run the coarse at 32 RPM. Apparently getting good mixing. But when I go to 500 grit I run them at 12 RPM. And get separation from filler.
As soon as I walked in the tumbling area I could hear heavy rattling in the 12 RPM obsidian tumbling barrel.
The shafts sit at a slant to keep them against the side roller on the downhill end. The bare obsidians were in the up hill side of the barrel with no filler.
So in one day at the 12 RPM move I bruised about the whole load.
The rhyolite and unakite are about impossible to bruise, no kid glove treatment required. like agates.
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,607
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Post by jamesp on Dec 16, 2014 12:19:19 GMT -5
captbob If sugar starts getting used again you may want to get leveraged heavily and purchase sugar commodities now that you have insider info.... Captbob, I pre-ground those obsidians long ago. They had about perfect shape after 7 days in SiC 30/60 long ago. I even pre-ground about all of the surface fractures out. Lots of waste. But lost most of the fractures. Great starting condition for coarse grind. I keep re-running them to remove bruises. I figured out where the bruises are coming from. (post above) So that problem has to be solved(shorter barrel for better mixing). A lot of opinions on jumping from 30/60 to AO 220. Which I have done 5 times. I still feel that the 220 is totally removing the 30/60 scars. And some. I have a fine Lortone 12 pound shorter barrel. I will start over using it on the obsidian. I have seen fine obsidian done in 3 pound barrels. Smaller may be gentler. Will also say with out a doubt, the bigger obsidians reap havoc in getting bruised. The 2-6 ounce chunks are a problem. They represent about all the bruises. And they hit the smaller pieces too. Your point about bigger is bang on. I used smaller stones w/out bruises for past photos, figuring the big ones are going to have bruises any way, like collateral damage. Price of doing business so to speak. Darn bruises really show in 500 grit stage, so early detection issues are a problem too. I was curious how your run was doing. The coarse would take a month or two if not pre-shaped in my barrels. So your run time sounds normal for not being shaped. I have to say, by selective pre-shaping a lot of material is saved. It is usually 1 or 2 sides that need a lot of removal. Instead of the tumbler removing material off all 5-6 sides, it is non-selective. Dallasite, rhyolite, all agates including stone canyon, unakite, are probably no brainers compared to obsidian. snowmom is sending me some breccias that resemble dallasite, so going to give that a try first. Then see if I can swindle bc out of dallasite. And I have some crazy basalt and devil's toenails I collected in Texas to tumble. Will see if it will take a polish. Check em out 
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,607
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Post by jamesp on Dec 17, 2014 12:49:35 GMT -5
captbob I just restarted some bruised obsidian in a short rubber Lortone barrel. Am surprised how quiet it is, have not used it in years. Starting over with AO 46. Slow 12 RPM. 7/8 full barrel. 50% glass filler.
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,607
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Post by jamesp on Dec 18, 2014 13:24:18 GMT -5
Heated samples(2) rhyolites not taking an easy polish like the green unakite, matte only. Could be the heat treatment softened them. They may do better in a pure rhyolite load, instead of being mixed with all agate. Will start a load of pure rhyolite in the vibe today in 1000, coming out of 500 in rotary. Dialed the Viking down to way slower. It makes a revolution in about 40 seconds instead of 10 seconds, much gentler. Just finished a load of larger coral. Noticed a little of the glass filler had chips, probably too many bigs in the batch. Not good for the rhyolite. bsky4463, the heat may have softened the rhyolite. Or my procedure was bad. Had a piece of fluorite in the rotary w/the rhyolite. It bruises/frosts like obsidian. No surprise. |
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Post by 1dave on Apr 6, 2022 15:17:13 GMT -5
 This Image is from jamesp Dec 7, 2014 at 8:40am Oh yea, this is the 16 pounds before chipping, sawing, grinding and heating  can be surrounded by agate forming spectacular patterns.  Lavic 4. Highly siliceous Ash Flow Tuff racing along at 300-400 mph can produce amazing Moss, Plume, and Flame patterns.  5. Metamorphic volcanic rocks such as rhyolite can also provide desirable colors and pasterns.  Indian Blanket - posted by beefjello [/quote] Imagine the material and patterns available with a little search - - -  The bottom layer is like a D-8 track. foot after foot sticks to the ground, then tries to get picked up again, but is jamed up, partially stuck to the layer above and below Spherulites  |
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,607
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Post by jamesp on Apr 7, 2022 4:57:09 GMT -5
Great memories 1dave. Rhyolites rock, some of the finest colors and patterns found on earth. Higher silica level has a lot to do getting a high tumble polish. |
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