jamesp
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Post by jamesp on Oct 20, 2014 6:16:17 GMT -5
This obsidian is so sensitive to abrasion and frosting. Still running barrel slow at 12 RPM. Larger 1.5-2.3 inch ave. pieces. Only 15% glass filler ave. 1/2 inch. So off balance due to shortage of middle sized stones. A full 15 pounds of 'big' roundish obsidians loaded first to 90% barrel fill. Only enough filler added to fill gaps to maintain 90% barrel fill of large pieces. And not much filler at 15% by volume to fill gaps. Had to spin the barrel couple of times to get the filler mixed. Slurry thickened with sugar, only like milk, but slick, mostly for lubrication. Running AO 220 step, today is 3rd day. However, barrel over 90% full. Even at +90% the 220 finish is happening. There is no way impact damage could occur. Too gentle. Overly full barrel and this stuff is still grinding quickly. And losing rock volume. Will top off to +90% with filler today to make up for lost volume. No doubt, losing mass. Still early in the 220 step, but am getting a 220 finish. Grind is slower than 80% barrel. But still fast compared to agate. A good 220 grind needed to remove the deep scars from the faster 30/60 coarse grind that also had light frost damage on the edges. This time whiteout marks 3/8" apart used as a reference in photos. After 2 weeks in 30/60: After 2 days in AO 220: After 3 days in AO 220 Full stone above
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Post by snowmom on Oct 20, 2014 7:36:41 GMT -5
watching with interest
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jamesp
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Post by jamesp on Oct 20, 2014 7:50:46 GMT -5
Thanks snowmom. Trying to get the biggest bang for the dollar.
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Post by captbob on Oct 20, 2014 8:33:06 GMT -5
At 12 RPM and using a barrel with a round interior, at 90% full do the rocks even tumble? Or do they slide?
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jamesp
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Post by jamesp on Oct 20, 2014 8:44:40 GMT -5
At 12 RPM and using a barrel with a round interior, at 90% full do the rocks even tumble? Or do they slide? There is a light series of tapping sounds captbob. not sure about the movement, I think the hard abrasive is cutting the obsidian like hot butter. I know from the last run at 7/8 full the volume dropped a lot in the 220 stage. Stones obviously smaller. Mohs 9.1 vs Mohs 5.5.
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jamesp
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Post by jamesp on Oct 20, 2014 10:19:51 GMT -5
At 12 RPM and using a barrel with a round interior, at 90% full do the rocks even tumble? Or do they slide? Just added 2 cups of small glass filler. I took the other loud barrels off and listened carefully. The PVC transmits the noise well. It is all sanding noise. Slow sanding. Very light taps too, but the sanding sound is prevalent. Pulled a stone and washed the sugar off in hot water and let it dry. It looks to have a fine satin finish over the entire stone. Very gentle action. But getting great abrasion results. This stuff is of course black and shows defects well. I now know that obsidian is really sensitive to wear, way more than I imagined.
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Post by captbob on Oct 20, 2014 10:36:42 GMT -5
SEEMS to me that the sanding would take place between the rocks and the PVC by the grit between the two.
I'm just wondering that if there is not tumbling (just sliding) taking place, is there enough chaos inside the tumbler to result in the entirety of all the rocks to evenly experience (benefit from) the abrasion. Or, are the rocks too stationary (sliding) so that maybe the side against the PVC tube is receiving more abrasion/smoothing (your sanding noise) than the parts of the rock not in contact with the PVC.
Maybe this would show best on large rocks which may slide more and tumble less?
I guess I am wondering if the RPM is too low?? You're on site, so you can make such calls, whereas I'm just speculating. I would just want to know the rocks were tumbling. Maybe by higher RPM but using more cushioning.
I'm sure they will turn out fine and this is all just an exercise in over thinking - on my part! Prolly sumtin' more important I should be doin'
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jamesp
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Post by jamesp on Oct 20, 2014 11:42:01 GMT -5
SEEMS to me that the sanding would take place between the rocks and the PVC by the grit between the two. I'm just wondering that if there is not tumbling (just sliding) taking place, is there enough chaos inside the tumbler to result in the entirety of all the rocks to evenly experience (benefit from) the abrasion. Or, are the rocks too stationary (sliding) so that maybe the side against the PVC tube is receiving more abrasion/smoothing (your sanding noise) than the parts of the rock not in contact with the PVC. Maybe this would show best on large rocks which may slide more and tumble less? I guess I am wondering if the RPM is too low?? You're on site, so you can make such calls, whereas I'm just speculating. I would just want to know the rocks were tumbling. Maybe by higher RPM but using more cushioning. I'm sure they will turn out fine and this is all just an exercise in over thinking - on my part! Prolly sumtin' more important I should be doin' Seems like a sweet 220 finish. A heck of a lot better than the 30/60 three days ago. Not sure about the devices within. Visual tells a lot on the coarse grits. The finer ones are a different story. I am suspicious that the polish should be done very gently too. I ran into this fast grind when tumbling the batch on that monster thread. I thought I had a 220 finish after 24 hours on that batch. So as a test I filled the barrel to the max on this run. And feel comfortable judging the change w/the coarse grit.
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jamesp
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Post by jamesp on Oct 21, 2014 7:21:53 GMT -5
Looking at the fullness and speed of a barrel and the effects. Relating it to sensitive obsidian. Worst case scenario, fast rotating large tire tumbler, beat hard agatized coral to pieces: Out side of tumble from the tire crusher: Inside of same rock chipped away: More damaged rocks from this violent tumbler, same material as above It is obvious that those rocks were tumbling way to hard. Guessing that tumbler manufacturers find a sweet balance in speed for their tumblers. Some rocks can take fast, some must go slow, so the manufacturer find a happy balance. Probably designed for quartz type gems. most popular... Pretty sure they were not designed for obsidian. Unless filler, padding, thickeners and all that other stuff is used. Agates don't need fillers or padding in factory machines. So experimenting with 90% full barrel and slow 12 RPM plenty of grinding and shaping is taking place with ease. Perhaps a lubricant is needed to assist movement in such a full barrel. Quartz and obsidian a world apart, no comparison. Seems the standard 25-35 RPM octagonal barrel is just to much. Especially at the finer grits. Wondering if the problem of getting a great polish on obsidian is very mild impact. The finer the grit the more the damage shows. This sensitivity issue is very similar to tumbling large rocks together. Same damn thing. The slow full barrel has been the ticket to doing large tumbles together. When two 10 ounce rocks are rolling hard against each other impact is way higher of a force than two 1 ounce rocks. I think the formula is mass X velocity. That is the minimum, anyway. Probably the square of the velocity, but it is constant with fixed speed barrel. Factory units always specify a range of rocks, and warn you about big ones, or let you find out on from experience. So filling the barrel to it's fullest is the easiest way to soften a tumble w/out additives other than a possible needed lubricant. The tire tumbler is basically a 1/3 full barrel with a long rough avalanche within. worst case scenario.
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Post by connrock on Oct 21, 2014 7:26:33 GMT -5
I think captbob is right about the obsidian just sliding and not tumbling much. One reason is the RPM'S and the other is that (in my opinion) if a barrel is 90% full there's no room for an actual tumbling action inside the barrel. I think the rocks are more or less like a honey comb in the barrel and mostly just rubbing against each other as the barrel rotates and the obsidian slides down the side? Although you are getting a good bit of wear on the obsidian I don't think this is the most efficient/fastest was to "tumble" the obsidian??? I think you would get more wear if the obsidian actually did tumble?? connrock
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jamesp
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Post by jamesp on Oct 21, 2014 7:43:09 GMT -5
I think captbob is right about the obsidian just sliding and not tumbling much. One reason is the RPM'S and the other is that (in my opinion) if a barrel is 90% full there's no room for an actual tumbling action inside the barrel. I think the rocks are more or less like a honey comb in the barrel and mostly just rubbing against each other as the barrel rotates and the obsidian slides down the side? Although you are getting a good bit of wear on the obsidian I don't think this is the most efficient/fastest was to "tumble" the obsidian??? I think you would get more wear if the obsidian actually did tumble?? connrock We have good timing this morning, brilliant minds think alike ?? My opinion is stated in the above post a minute ago. Am pretty darn sure material removal is not a problem. Losing volume rapidly in 220 grit. 2-3 cups in 3 days. No doubt that it is grinding material away. Having to add filler. This time only 15% broken glass filler by volume. After 3 days in 220, way smoother than the 30/60 finish:
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jamesp
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Post by jamesp on Oct 21, 2014 11:39:50 GMT -5
I think captbob is right about the obsidian just sliding and not tumbling much. One reason is the RPM'S and the other is that (in my opinion) if a barrel is 90% full there's no room for an actual tumbling action inside the barrel. I think the rocks are more or less like a honey comb in the barrel and mostly just rubbing against each other as the barrel rotates and the obsidian slides down the side? Although you are getting a good bit of wear on the obsidian I don't think this is the most efficient/fastest was to "tumble" the obsidian??? I think you would get more wear if the obsidian actually did tumble?? connrock I think you are gonna think I am a nut case Mr. conrock. Moving to AO 500 grit. Removing all filler. 16 pounds of pure obsidian. All business. 6 cups sugar, 90% full, 12 RPM. Going to do pure obsidian all the way thru polish. Check out the load, adding some poorly polished obsidian to replace the filler. This should be interesting. Feeling confident with the slow speed, sugar and 90% barrel fill. The large pan was the AO 220 load:
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jamesp
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Post by jamesp on Oct 21, 2014 19:13:04 GMT -5
Polished ones losing their polish to 500 grit in 6 hours. More so on flat areas, edges slower. Barrel close to 95% full. 100% full of water. Testing wear pattern by removing polish. Just taking it to the extreme by doing 95%. Will probably remove stones back to 90%, water to 90%. Looks like this will work. May reduce sugar and add pulped newspaper on 1000 and polish stages. 2-10 micron mix arriving next week from Lortone. Effects of AO 500 on polished stone after 6 hours. Flat center area completely frosted, slight glare circle, edges slower but loosing polish Starting polish before AO 500, same light, 2 angles, one showing sheen, one not Stones from AO 220 will be compared to polished stones as AO 500 grinds. From a technical article about glass, the effect of speed on dragging a diamond point across it: "On glass with increasing speed one observes successively chipping plus irregular median cracking, lateral cracking plus irregular median and sub-surface cracking and only smooth median and subsurface cracking." So, maybe slow is a good thing, not sure what all that means except speed seems to cause more damage.
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Post by connrock on Oct 22, 2014 8:09:20 GMT -5
I'm gettin scared here cuz usually when someone calls me Mr. they want something??? LOL Also,,,you spelled my last name wrong(conrock).It's CoNNrock! The only one in my family who changed his last name is my cousin Zeke who is (3 times removed).He changed his last name to Cornrock! LOL
I think with the wear showing on the flats of the "prepolished" obsidian proves that the rocks are not "tumbling" but rather rubbing against them selves?Normally it's the outer edges of the rocks that wear down first.
Why did you fill the barrel to 100% with water? connrock
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Post by captbob on Oct 22, 2014 9:06:13 GMT -5
No filler this time, right? Looks like ya need the smalls to get to all areas.
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jamesp
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Post by jamesp on Oct 22, 2014 10:05:08 GMT -5
I'm gettin scared here cuz usually when someone calls me Mr. they want something??? LOL Also,,,you spelled my last name wrong(conrock).It's CoNNrock! The only one in my family who changed his last name is my cousin Zeke who is (3 times removed).He changed his last name to Cornrock! LOL I think with the wear showing on the flats of the "prepolished" obsidian proves that the rocks are not "tumbling" but rather rubbing against them selves?Normally it's the outer edges of the rocks that wear down first. Why did you fill the barrel to 100% with water? connrock The computer spell checks your name and it got corrected by a human. haha. Will avoid that error and please forgive. Connrock better than Cornrock. Ah, computer put red lines under both. Is their an illiterate computer on the market ?? Yep, you have it exactly. Rubbing and not tumbling. Edges do wear first when they tumble. I will pull a polished one today and see if the 500 frost has worked it's way over the whole stone. The flat area is totally frosted, and the edges are getting frosted, just slower. Removing the polish is probably easier than grinding off the 220 finish. Don't you think? The other obsidian batch seemed to do the opposite. They were tumbling. The edges did wear faster but also got more bruises. So was going backward watching what happens if they 'rub'. So polish finish and 220 finish is being removed in the same barrel. This time comparisons can be made. Still got 5 pounds of polished ones to experiment with. They had a crappy polish on them anyway. And some 220 finished ones were set aside to experiment with too. The 100% water was to slow the rolling impact. They were still tapping on the top of the load. Apparently the 500 grit is suspended in the slurry since they are grinding. Coarse grit and 220 would certainly wash off. Conclusion of all this is to slow everything down and try w/out filler. The filler in the last load had a mirror polish. Not the obsidian... And tried several glass fillers. They were all shinier than the obsidian. So trying 100% obsidian rubbing on obsidian.
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jamesp
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Post by jamesp on Oct 22, 2014 10:38:17 GMT -5
No filler this time, right? Looks like ya need the smalls to get to all areas. It is a very boring tumble captbob. Slow and quiet. More of a 'rubble' than a tumble. The various glass fillers used on the last tumble had all the shine. As you know the hardest material usually gets the polish in a rotary. So the glass filler ain't going in for the polish stage this time. So trying to slap a 500 finish on these w/out filler. If a good 500 finish happens w/out filler, then there is a chance polish will happen w/out filler. Have always tumbled w/out filler. But ran similar materials- agate w/agate, or rose quartz w/rose quartz, or granite with granite. That worked. And trying to get this done w/out filler dang it. I hate filler. It takes up valuable tumbling space and it has to be managed/segregated. Gotta be a way w/out filler.
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Post by captbob on Oct 22, 2014 11:14:35 GMT -5
I had a long post written out which I prefaced with "I probably shouldn't post this"
so I didn't
we simply disagree.
I am sure you will prevail and your load will be awesome. Whether you chose the best path to awesome will always be debatable; best being relative.
I will watch your progress with interest.
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jamesp
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Post by jamesp on Oct 22, 2014 13:44:58 GMT -5
I had a long post written out which I prefaced with "I probably shouldn't post this" so I didn't we simply disagree. I am sure you will prevail and your load will be awesome. Whether you chose the best path to awesome will always be debatable; best being relative. I will watch your progress with interest. It is just an experiment captbob, keeps my mind occupied. However....THE EXPERIMENT IS KICKING BUTT. Pulled 20 and washed that dang sugar off and let em dry. They are at 24 hours. Observed them in the bold sun at a 90 degree angle. A 220 finish CAN glitter in strong sun light, a 500 finish will give off a spectral haze, it CANNOT glitter. If it does ya got 220 marks left in it. Yes, a few glitters from a defect or gas bubbles is going to stay. Still have a slight glitter on the slow grinding edges. Time will get those. I could tell the 220 finished one that was set aside for comparison from 5 feet away. The polished ones have completely lost their shine. No doubt in my mind that i am 24-48 hours away from a 500 finish. The rubbing is getting it done. It would never work on coarse, but does well on 500. Hoping for it to work on 1000 and polish. Water kept at 100% full. To cushion falling rocks on top. They still roll. Barrel still at 95%... This batch different, I have others to compare and add as needed. Intend to try fluorite w/same rubbing process. Other softies too. It is just a different mechanical process. Just not conventional.
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Fossilman
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Post by Fossilman on Oct 22, 2014 13:48:44 GMT -5
Looks like its coming along James...
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