jasperfanatic
spending too much on rocks
Member since January 2019
Posts: 456
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Post by jasperfanatic on Feb 14, 2019 16:27:51 GMT -5
To anyone actively tumbling obsidian in a vibe (more helpful if also a UV-18, if results vary by equipment), I'm hoping to get some clarification on how do deal with chips/bruising. I've searched the forum and there is a LOT of information there, but it seems like adding some amount of sugar helps to cut down on that? Is there a winning recipe out there? To get to where I'm at I kind of Franksteined some thing together starting with tntmoms recipe, some other things I've read and then a healthy dose of trial and error. Originally I was using AO 1000 from some grit kit purchase, but the shine sucked. I had some unused Loritone AO polish (not the AO pre-polish) and that produced an amazing shine (and I now have some of the AO polish from the Rock Shed just in case), but the problem is that damn near every piece had a chip/crack/bruise. Nothing big that couldn't be dealt with, but they have to be redone, and I want to figure out how to avoid that next time. I'm using small ceramic pellets with the bowl being loaded with 3/4 pellets to 1/4 obsidian of different sizes. I did have 3 or 4 pieces of jasper in there (I was testing the shine), and at first I thought that was the problem since jasper is so much harder, but seemed unlikely that was the biggest culprit since all but maybe 6 pieces were bruised.
I'll definitely make the next go at it obsidian only, but I'm thinking I need to make some other adjustments to defeat the bruising, and I'm hoping someone can help me focus on the best adjustment since there was so much information to parse through in the search.
Is sugar the answer? If so, is it just because it thickens the slurry?
The shine on this batch was amazing! So disappointing to find they'd all been dinged at least once.
Thanks in advance for any helpful hints!
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rodeodan
starting to spend too much on rocks
Member since January 2010
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Post by rodeodan on Feb 14, 2019 17:33:28 GMT -5
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jasperfanatic
spending too much on rocks
Member since January 2019
Posts: 456
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Post by jasperfanatic on Feb 14, 2019 18:13:08 GMT -5
That's the recipe I started from, but thank you! At this point, the only issue I'm having is with bruising during the polish stage. I've been forming in the rotary, hitting the occasional piece on the grinding wheel if it had some crevice that was going to take too long in the rotary, and then polish in the vibe. It's just that bruising/chipping I need to figure out now.
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gatorflash1
spending too much on rocks
Active in Delaware Mineralogical Society, Cabchon Grinding and Polishing, 2 Thumlers B's and a UV-18
Member since October 2018
Posts: 375
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Post by gatorflash1 on Feb 14, 2019 18:13:16 GMT -5
You might see if anyone is tumbling glass in a UV-18 and if so what recipe they use.
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Post by grumpybill on Feb 15, 2019 7:32:39 GMT -5
No experience with the UV line of vibes, but I've never gotten bruises on glass or obsidian in a Lot-O. I have had some glass slag break at the seams/layers, though.
Maybe try filling the UV bowl fuller? More weight = less forceful action.
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Post by HankRocks on Feb 15, 2019 9:18:53 GMT -5
I use a UV-18 for final polish. My suspicion is that it is a bit too violent with the vibrations. It polishes agate and wood very nicely. Quartz and Obsidian can get some bruising. Had to replace the center bolt twice no and each time while the machine was completely dis-assembled to do this considered replacing the counter weight to see if that softened the vibration. So far I haven't tried it. I did modify the center bolt to 1/4" from the 3/16" on the last replacement hoping it will last longer.
Do you have enough smalls in your tumble mix? Too many large rocks can be an issue. I use a good bit of smalls in my polish stage, both previously polished Pea Gravel and pre-form trimmings. They seem to help. That and I re-use the polish/borax so I end up with a lot more than the normal amount of polish slurry, another buffer. You need to watch so that the consistency of the Polish slurry as I call it is not too watery and not too thick, but stays nicely coated on the rocks and you get good rock movement. I estimate that I add about a cup or more of previously used and somewhat dried out polished slurry to a batch. If it's too watery I add a bit of Borax and polish until it thickens a bit.
Good luck
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Fossilman
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Post by Fossilman on Feb 15, 2019 10:22:28 GMT -5
More filling than material, is the key.....
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Post by gmitch067 on Feb 15, 2019 16:39:22 GMT -5
I have used my UV-18 to polish obsidian jasperfanatic . The following is my own personal recipe... First the rotary tumbler preps ( I try to keep the size of obsidian rough to around 1-1/4 to 1-1/2 inch pieces, and try to avoid larger stones - because I see more chips to other pieces when they are included): I use the QT-66 - 6 lb rotary(s) to give the initial shape using SiC 80-grit (not 60/90-grit like I usually use with jaspers), checking it every 4 days to see progress, and separate out those that are well shaped and chip free. I use a 50/50 blend of already fully polished quartz aquarium gravel (1/4 in. to 1/2 in.) and obsidian. I use a 1/4 cup of kitty litter per 6 lb. drum as a thickener. Some folks use sugar as a thickener but I have not tried it yet. This stage takes awhile as I am continually running new obsidian and removing the shaped ones until I have about 4-5 lbs. reserved for further processing. If the load needs to be split between two rotary tumblers I add more gravel as filler per tumbler. It is during this first 80-grit stage that I have sometimes noticed bulging of the tumbler's rear wall from gas build-up that needs to be "burped" before it can explode the lid off... not often... but... check a few times a day for a few days to make sure. This doesn't seem to be a danger after the 80-grit stages. Next comes more rotary tumbling using SiC 220 with 50/50 mix of polished aquarium gravel and obsidian... only this time I only run the loads for 7-10 days. NO kitty litter as a slurry thickener. At the end of this process I am usually left with about 4 lbs. of obsidian. If I find any that are chipped, they go back into another SiC-220-grit run. Shift to using the UV-18 - and use of Aluminum Oxide grits and polish (Amazon has the 220-grit Aluminium Oxide... If you don't have it... I got good results using SiC-220-grit also... maybe... so-so?): The ratio of polished aquarium gravel to obsidian now changes (I DO NOT use the same aquarium gravel as used during the rotary tumbling... I shift to NEW and fully polished gravel) ... The obsidian goes into the bowl (about 4 lbs.) followed by enough 1/4 to 1/2 in. fully polished gravel to reach up to the top of the cone (no higher). No thickeners are added to any of the vibe loads. From now on the vibe process goes as follows: 2 days AO-220 (or SiC-220 if you don't have AO) 2 days AO-500 1 day AO-1200 1-2 days AO-14,000 polish (usually only 1-day is necessary) The same aquarium gravel is used throughout the full vibe process. I have also used Tin Oxide and Cerium Oxide polish but can't tell which is best... they all did well. I have also done the UV-18 runs using only SiC-grits for 220, 600, and 1200 but the obsidian did not come out so lustrous as when just using the Aluminum Oxide grits. 'Hope this helps. Glenn
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jasperfanatic
spending too much on rocks
Member since January 2019
Posts: 456
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Post by jasperfanatic on Feb 15, 2019 18:14:59 GMT -5
Thanks for sharing that recipe, gmitch067. Do you get any bruising/chipping at all? I think Fossilman's ration suggestion makes some sense, and while I felt like it was definitely very heavy on the filler side of things, I may have had too much obsidian. I'm just curious if a flawless run is possible, or if it is just about maximizing how many come out successful knowing that every run will have 1 or 2 casualties that will need to be included in subsequent runs.
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Post by gmitch067 on Feb 15, 2019 22:14:26 GMT -5
When you are running a 4 lb. load in the UV-18 of glass or obsidian expect some breakage or bruising... can't escape that. I believe that using greater filler with smaller stones is the key for obsidian. Every time I have tried to process larger stones I have seen a lot of chips... and many times frosting. I recently tried to produce a good shine on 9 large blue glass stones (all about 2-3 in. - from The Rock Shed) using the above recipe and was met with failure due to frosting (one chipped). I repeated the UV-18 vibe steps AO-500, AO-1200, and AO-14000 polish one more time using aquarium gravel and another time using large/small ceramics.... still failed... very little breakage, but still frosted. I even tried the same fillers using the Lot-O and Mini-Sonic MT-4 with only one stone at a time... still frosted (grumble grumble grumble...) Sooo... once again ...in my opinion... using greater filler with smaller stones is the key for obsidian and glass when using the UV-18. Glenn P.S. to jamesp ... You are a VERY hard act to follow... Your DIY tumblers are MAGIC!
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jamesp
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Post by jamesp on Feb 16, 2019 10:11:34 GMT -5
I did find the secret to doing glass gmitch067. And probably many soft stones. I did over 30 - 6 pound loads of glass in 2018 because it only takes about 10-12 days from start to finish. Did not take many photos, but here is a 'shine' album of the average polish www.flickr.com/photos/67205364@N06/albums/72157704862373114Said it once, said it a hundred times. Factory vibes are better for agates and Mohs 7 stones w/exception Lot-O and apparently Mini Sonic. The Lot-O has limitations. No experience with the UV jasperfanatic. *****You need shorter vibrations and lots of power for thick slurry.***** The Vibrasonic is flexible and way powerful with a 1/3HP 3450 RPM motor. And the Vibrasonic has the power to make the glass move in a thick(preferably sugar) slurry. The Vibrasonic is the most flexible vibe built because it handles many different hopper sizes and shapes from 8 to 50 pounds that can be bolted down to the top deck of the machine. Makes experiments easy. Most factory vibes are not easy to modify or make such changes. They are fixed machines. Installed a low heavy hopper on the deck of the Vibrasonic that is close to the Vibrasonic vibration source it created the needed short gentle vibrations for glass. Install a tall hopper further from the vibration source creates long vibrations that will bruise the hell out of glass, but fine for agate. Simple as that. The Lot-O will do glass but it takes a long time and requires more steps and more media because it does not have enough power to handle thick slurry. My modified Vibrasonic will break down AO 220 in 4 days to about AO 5000 even in thick slurry using only 25% media. You can protect with lots of media and use up your valuable hopper space or you can accomplish the same effect with thick slurry and not waste hopper space with media. But if the vibe is too violent media will not fix the bruises. *****You need shorter vibrations and lots of power for thick slurry.***** PS Large pieces of glass(over 25 grams) are very difficult to polish with out bruising/frosting. Beyond my capabilities anyway.
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jasperfanatic
spending too much on rocks
Member since January 2019
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Post by jasperfanatic on Feb 16, 2019 11:46:29 GMT -5
Thanks, jamesp...my wallet has suddenly become very nervous.
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jamesp
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Post by jamesp on Feb 16, 2019 12:30:41 GMT -5
I too had a wallet issue. I just happened to find a Vibrasonic on Craig's list for $150 which left $/confidence in the budget to do modifications to it. In the end the only modification preformed was welding up a lower profile hopper out of scrap steel that was much heavier than the factory hopper to alter(numb) the vibration characteristics and bolting it to the top of the universal Vibrasonic base using the same fasteners as the factory hopper.
Glass/obsidian is easy to tumble in a rotary without causing bruises if you keep the barrel at 85% fill. Glass/obsidian is 'often' tumbled in a vibe with say AO 500 without experiencing bruises because AO 500 creates protective slurry. However AO 1000 and AO 1200 does not create much protective slurry and leaves the glass vulnerable to bruising, simple as that.
To further aggravate the bruising issue, the finer the finish the more susceptible glass is to 'micro' bruising and/or just plain ole bruising. Micro bruising is difficult to delineate from a poor polish or no polish at all because it is on a microscopic level.
The problem that trumps all problems though is the vibe being too violent. Thick slurry and/or any amount of media will not solve the problem. The UV is a bowl type vibe and those machines appear to be difficult to modify for numbing.
Anyway, those are my findings for what it is worth.
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jasperfanatic
spending too much on rocks
Member since January 2019
Posts: 456
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Post by jasperfanatic on Feb 16, 2019 12:38:10 GMT -5
Anyway, those are my findings for what it is worth. It's worth a lot! I really appreciate the wealth of knowledge shared! Other than seeing it mentioned, I hadn't actually "thought" about all that a more aggressive vibe could impact. I may try to see if there is some modification I can make to the UV that might achieve that, but that is going to lock up the one vibe I have for months of testing, so at the very least I'll need another vibe of some sort to keep working with the harder material
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Post by gmitch067 on Feb 16, 2019 12:52:50 GMT -5
Interesting nugget of information jamesp about the use of AO-1000 and AO-1200 as unable to produce a viable slurry and adding to the possibility (probability) of bruising. I will have to eliminate that step from my recipe and see how that goes. On using sugar as a thickener... would that allow the AO-1000 to work on softer stones using a vibe? If so, how much (or is that a matter of feel or "see what happens and adjust the amount")? Thank you again for the advice. Glenn
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jamesp
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Post by jamesp on Feb 16, 2019 13:24:05 GMT -5
Anyway, those are my findings for what it is worth. It's worth a lot! I really appreciate the wealth of knowledge shared! Other than seeing it mentioned, I hadn't actually "thought" about all that a more aggressive vibe could impact. I may try to see if there is some modification I can make to the UV that might achieve that, but that is going to lock up the one vibe I have for months of testing, so at the very least I'll need another vibe of some sort to keep working with the harder material I see your point. If at all possible get a used Vibrasonic on EBAY or Craig's list for reasons mentioned. In those tests I found a particularly narrow 'bandwidth' of vibration that was friendly with glass. Agate and other hard stones have a wide bandwidth making it easy to build a vibe meeting those needs. It sounds an oxymoron, more power for the thick slurry but shorter vibrations. Those are two different properties. Analogy - shaking a gallon of paint 3 inches left to right verses a pint of paint each 3 inches left to right say 3 times per second takes more power in your arms for the gallon. Make sense ? Adding weight to the hopper can create out-of-control issues unless the center-of-weight of the hopper is moved closer to the vibration generator which numbs sharp damaging reversals. Moving the hopper closer to the vibration source (like bouncing on the end of diving board verses middle of diving board) creates shorter travel. Easy to do on the Vibrasonic because of it's design, not so easy with a bowl hopper vibe with center axle vibration generator below hopper.
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jamesp
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Post by jamesp on Feb 16, 2019 13:45:02 GMT -5
Interesting nugget of information jamesp about the use of AO-1000 and AO-1200 as unable to produce a viable slurry and adding to the possibility (probability) of bruising. I will have to eliminate that step from my recipe and see how that goes. On using sugar as a thickener... would that allow the AO-1000 to work on softer stones using a vibe? If so, how much (or is that a matter of feel or "see what happens and adjust the amount")? Thank you again for the advice. Glenn 10 tablespoons of sugar for 8 pounds of rock. Add water till pancake syrup consistency happens. You must let it run 5 to 10 minutes between adding water till you get the right consistency. Once you know the ratio simply record and repeat on future batches. But the thicker slurry did not solve the bruising problem with factory set up and adjustments. Tried it all. Neither did adding all kinds of media, even with 80% media. So I do not have faith that you will solve the glass bruises w/media and slurry in factory machine. Maybe some people can... ***I had to modify the vibe.*** This was an unforgiving experience, it took a long time before figuring this out. It did not make sense but it did the trick. It is the violent action of most vibes that causes the problem of bruising glass. Simple as that. The modified vibe is user friendly and accepts a much wider variation in recipes for our sensitive glass and obsidian. Actually about idiot proof. I have successfully polished glass with a half a dozen recipes because the machine's vibration is tuned for glass(does agate well too). Successively polished glass using AO 80-220-500-1000-polish in various vibe recipes. Some with SiC grades in early vibe steps too. As little as 20% media, never required more than 30%. tumbler's delight
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Post by HankRocks on Feb 16, 2019 20:28:30 GMT -5
I too had a wallet issue. I just happened to find a Vibrasonic on Craig's list for $150 which left $/confidence in the budget to do modifications to it. In the end the only modification preformed was welding up a lower profile hopper out of scrap steel that was much heavier than the factory hopper to alter(numb) the vibration characteristics and bolting it to the top of the universal Vibrasonic base using the same fasteners as the factory hopper. Glass/obsidian is easy to tumble in a rotary without causing bruises if you keep the barrel at 85% fill. Glass/obsidian is 'often' tumbled in a vibe with say AO 500 without experiencing bruises because AO 500 creates protective slurry. However AO 1000 and AO 1200 does not create much protective slurry and leaves the glass vulnerable to bruising, simple as that. To further aggravate the bruising issue, the finer the finish the more susceptible glass is to 'micro' bruising and/or just plain ole bruising. Micro bruising is difficult to delineate from a poor polish or no polish at all because it is on a microscopic level. The problem that trumps all problems though is the vibe being too violent. Thick slurry and/or any amount of media will not solve the problem. The UV is a bowl type vibe and those machines appear to be difficult to modify for numbing. Anyway, those are my findings for what it is worth. I just occurred to me that one big difference between the UV-18 and the Lotto and the Multi-sonic is the composition of barrels. The UV-18 is hard plastic and I believe the Lotto and the Multi-sonic are both softer rubber(correct?) The hard plastic has to be adding to the vibration affect, and the hard walls insteadof softer rubber to collide with. That has to make a difference. I have my sights set on a multi-sonic triple barrel that should help me out, as long as it still runs!
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jamesp
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Post by jamesp on Feb 17, 2019 8:38:51 GMT -5
HankRocks. One hopper I use for glass is straight up steel with no liner, the other one is made of 2 Mini Sonic hoppers. For what it is worth they both perform equally. My Lot-O is softer(rubber) than the Mini Sonic's(plastisol). Don't laugh. Using the 9/16" wrench vibration analyzer to get this level of vibration on the dominate vibration direction seems to be the requirement for glass. Crude but effective. Wrench bouncing on steel, not plastic.. The wrench bounced much more before the mod. Pretty sure this gentle vibration is the answer. If your glass is bouncing and rattling across the top of the batch in the hopper expect probable frosting. Just started AO 220. 8 pounds including media. 10 tablespoons sugar. Just added fresh water so action is at maximum speed. Will be much slower in 24 hours for next 24 hour water addition. ***No bouncers on top. Basically a blob of glass and media stuck together and rubbing against each other in pancake syrup. The divider is there to prevent larger pieces accumulating to one side and banging without media. Steel hopper: Agate with Borax using dual Mini Sonic hopper. Faster action with the smaller Mini Sonics and thinner Borax slurry. *** No bouncers on top. This hopper does polish glass faster but has a smaller capacity than the steel hopper so in effect slower in total production.
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