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Post by Peruano on Feb 21, 2014 10:15:32 GMT -5
I'd like to promote a measured discussion of whether contamination (carrying of coarse grits forward in the tumbling cycle) is as valid a concern as most folks think. If grits are reduced in size each day as they grind away, having 100 grit carried into day 2 or 3 of a vibratory tumbler cycle should pose minimal problem because its more like 200 or 400. I do understand of course that if I have pitted rocks and if the grit hangs in the pits for 4 days and eventually is dislodged on day 5, I might loose some ground on my stones that have advanced beyond that grit stage (but how much of that happens or is likely to if I'm careful in screening rocks and doing a reasonable cleanup between major stages. I've heard that we all use too much grit (its helps keep suppliers in business)and by being 1. patient, and 2 minimizing our amounts of grit we can count on results just as good at less cost (i.e. an additional day with the same 200 grit may be just as good as washing out the grit after day 1 and moving to a second round of 200 or ??. Of course part of the basis for clean up is to get rid of sludge buildup, but that's mostly an issue with soft stones that are reducing their size rapidly. Maybe I'm biased by the mostly agate and agatized petrified woods that I tumble, but I suspect my trim saw fragments that I use in place of ceramic media, are just as important as the added grits. Are we throwing away grits that we should be leaving in place to continue the process? I, of course, realize the importance of eliminating grit from the polish phase, but thats days after my initial grinds and stages. Input is welcomed, but I'd be particularly interested in results instead of opinions based on lore. Am I a heretic or am I just challenging a system best left as is? Thanks for considerations. Tom
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Post by Jugglerguy on Feb 21, 2014 10:40:21 GMT -5
That's a great question, Tom. I've wondered the same thing. I use a Lot-O and my rocks look almost as good as they're going to look after three days in 500. The problem is, I've never run my 500 stage longer than three days. Actually, that's not true. I ran obsidian for four days according to TNTmom's excellent obsidian tutorial. Krystee's (TNTmom) pictures are the best evidence that I've seen that running 500 for a long time continues to improve results past a couple of days. The reason I haven't really experimented too much with the idea of running one grit longer and skipping stages is that I only use 1/2 teaspoon of 500, 1000, and polish. I'd only be skipping the 1000 stage, so it doesn't really save much money at all. If the 1000 stage is actually backing up a step (since the 500 should have turned to 4000 buy that time), then I would also be saving some electricity by not running the Lot-O so long.
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panamark
fully equipped rock polisher
Member since September 2012
Posts: 1,343
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Post by panamark on Feb 21, 2014 10:42:04 GMT -5
Hi Tom,
A very interesting topic for sure. I agree with most of your points. Up until the 500 or smaller stages, I don't think carry over is much of a problem (except for the big grit becoming lodged then released in voids as you mention). I am sure in the polish stage you have to be very careful, but I think a bigger concern for me is: 1) rocks chipping or fracturing during polish and the new rough edges ruin the others VERY quickly and 2)rocks of very different hardnesses which results in neither getting a good shine.
In my limited experience I don't think that you can get by with less grit and just substitute time. Of course at the extreme if you run agate for 6 months and no grit you can probably do some good. But I have found that if I skimp on the rough out stage grit or even the 220 grit stage, it takes much, much, much longer to get good results. To me it is not worth the time or the electricity. I agree that adding the saw fragments to my rough out tumble has helped significantly along with the ceramics. I usually take these fragments out for the polish as too often these thin smalls will break during polish and their rough edge hurts the polish.
Just me 2cents. Interesting and important topic. Thanks!
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SirRoxalot
freely admits to licking rocks
Member since October 2003
Posts: 790
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Post by SirRoxalot on Feb 24, 2014 9:43:39 GMT -5
I don't think you'll get an answer that's been proven by experimentation.
The neat thing about tumbling is that it's a relatively open and neglected field. I suspect that there's an individual out there, or maybe a big corporation that has studied stuff like this, but to the best of my knowledge they haven't published their findings.
Examples like this are ripe for experimentation. It would be nice to have a tumbling room lined with multi-barrel machines so testing could be done and we'd see how true these old chestnuts are.
Lots of possible things to try, like running dry, or using oil instead of water, or running with varying amounts of grit or no grit at all. Or trying to find a superior abrasive, or combining vibratory with rotary, or???
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daisyd681
starting to spend too much on rocks
Member since January 2011
Posts: 104
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Post by daisyd681 on Feb 24, 2014 11:24:54 GMT -5
You'd also have to have the same rocks in each tumbler for that experiment to work. The same sizes and shapes too.
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Post by johnjsgems on Feb 24, 2014 14:36:24 GMT -5
Talking only vibes I guess. The 220 (first step for me in vibe) is completely broken down after two days. I usually give bowl, ceramics, and rock a quick rinse and add new 220 (one teaspoon in my little Gy-Roc). After two days, another quick rinse and load with 500. Then a really good rinse or burnish before polish. Polish in separate bowl is the easiest way to save money as you can reuse the polish. Unless you want shiny rocks with fractures, pits and other flaws you should either grind away the flaws on a wheel or in a rotary. I tried just about every crazy variation for rotary tumbling and all seemed to work OK.
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Post by Peruano on Feb 24, 2014 14:51:45 GMT -5
Thanks everyone for the views. I just wanted to confirm the breakdown and its significance on how much I had wash or not. I just pulled out a bunch of agates and agatized wood polished with what I believe to be Linde A and was please with the shine (but not my photos). Now that warmer weather is here, its time to tumble, grind, and smile. Cheers everyone. Tom
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Post by johnjsgems on Feb 24, 2014 15:41:42 GMT -5
I for one think the people advocating surgically cleaning rocks between stages are either tumbling rocks not worth tumbling (major fractures, etc.)or a little obsessive/compulsive. A good burnish cleaning before/after polish works pretty well in both vibes and rotaries. A good rinsing between grit steps works for me.
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SirRoxalot
freely admits to licking rocks
Member since October 2003
Posts: 790
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Post by SirRoxalot on Feb 24, 2014 18:03:52 GMT -5
Ah, but you see, we've always been told that a flawless cleaning job betwixt stages is mandatory, as even a single stray grit will ruin everything!
I wonder if a few minutes in an ultrasonic would be a good idea, hrmmm.
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Post by radio on Feb 24, 2014 20:53:38 GMT -5
I have seen some nasty scratches on Obsidian that came from stray pieces of course grit that came out of a pit or dislodged from somewhere. A discussion of the exclamations made is not suitable for a family oriented forum
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,179
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Post by jamesp on Feb 25, 2014 5:18:26 GMT -5
This photo shows a contamination issue. This photo was taken in full sun so the shine is suppressed. It has a great polish. But it has scratches from the 30/60 grit. How the grit got in there is a mystery though. I ran them for 2 weeks in 220(rotary tumbler start to finish). That should have totally wiped out any scratches from the 30/60. I am pretty thorough about cleaning. I use a 3000 PSI pressure washer w/a 30 degree tip. Same material from same batch but a cloud rolled over during photo session and the shine is prevalent. Notice the vertical scratch in the dang center. In tumbling Savannah River agate i used 16 grit for coarse. Had hundreds of grit particles stuck in this porous material. But had an excellent polish and could not find a single scratch. You can see the grit particle is even ground level to the rock surface.
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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 25, 2014 10:38:27 GMT -5
Can't speak to vibes as I only have rotaries. Used to tumble wash between every step. These days I just do a good rinse between steps one two and three. Then when coming out of 600 (or 1000 if used) I do an extended tumble wash. 24 hours with a mix of ivory shavings and borax. Rinse out that barrel and go another 24 hours with borax. If the water pours out grey after the second wash I'll do another 24 hours with borax, but the third day is rare.
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Post by connrock on Feb 25, 2014 11:13:36 GMT -5
With a Lot-O-Tumbler,,,if the rocks are flawless and completely cleaned properly it is possible to get a good shine on hard rocks by only using a 1000 grit stage. I've posted this photo several times here to prove the point that grit does keep breaking down and if left to run it will produce a good shine on flawless rocks. If memory serves me right,,,the one on the left is Montana Agate and the one on the right is Brazillian Agate.They were part of a load I left in 1000 grit and Dreft powdered laundry soap for about 1 week. I doubt if there was any saving as far as money goes because of the cost of electricity to run that long and that I only use 1/2 teaspoon of polish per 4.5 lbs of rocks. connrock
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MrCoffee
has rocks in the head
Member since December 2005
Posts: 634
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Post by MrCoffee on Feb 25, 2014 21:55:34 GMT -5
I like to do pretty much what Connrock does, except I don't use any surfactants or detergents. I may hand wash with Dawn between stages, but that's about it. Anything that's not porous, shines very well. The real trick to this, is time. You want to run them long enough to break down the grit, and anything that might even remotely get stuck in a crevice will still be reduced to the size of the next stage anyway. I have even experimented with going directly from the 150/220 to polish, which would give a good polish. Yet, I prefer the 600 step, because it breaks down further. This makes the polish act more like a burnish, because the stones are shiny before they even go in.
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Post by pauls on Feb 25, 2014 23:21:38 GMT -5
I have acquaintances that tumble loads of Queensland agate and only use 45 grit, according to them the rocks are tumbled for up to a year before polishing. I have no idea how often they renew the grit and pick out the stones that are ready, but they were adamant that 45# was all they used. All their finished rocks were very round with a perfect polish so I believe that they do tumble for those sort of times.
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