The following is "raw material" from an older, less organized, text-only collection of tumbling information. I intend to merge it all into this new HTML file... ------------- Subject: Re: Tumble Polishing Obsidian To tumble-polish Obsidian, do not use Cerium Oxide or Tin Oxide; these, being acidic, react with the obsidian, which is alkaline, and the best you can usually expect is a soft matte finish. I can and have gotten good results with Tin Oxide using a very thick Tide (R) slurry, but that is because the Tide is SO alkaline, it overcomes the weak acidity of the Tin Oxide. Don't rely on it; it takes a long time. My best success has been with Raybrite (R), which is Aluminum Oxide, Octagon Process (R) liquid detergent, smashed walnut shells, screened thru 1/8" mesh, and only enough water so that the whole mass will move. (I use a teaspoon!) Put it on and forget it for a week. (Unless you're using vibratory tumbler, which I don't recommend because Obsidian spalls like crazy unless you're using so much carrier that there is no chance for obsidian to strike obsidian) Open it up and look. Here is the trick that very few people know. OBSIDIAN, ONCE POLISHED, UNPOLISHES READILY! So, once it has almost polished, look at it every hour or so until it has reached the shine you want. Turn it off at night. I know; that's a sin you're not supposed to commit, but if it's polished at hour 3, it would probably be unpolished by hour 8! It's mighty persnickety stuff, but the results are worth the extra care. Oh -- and pellets are a poor choice for carrier on obsidian; walnut shells or rice hulls work much better. Leather punchings are good, too. Ted Robles erobles24@hotmail.com ________ From: lapidary@mindspring.com Date: 20 May 1999 13:21:17 EDT Subject: LapDigest #210 To: LapDigest@mindspring.com Subject: RE: How to Polish Chalcedony Roses Polishing Chalcedony roses: this brings back a happy memory. My wife and I had collected a lot of small chalcedony roses from the foot of the Cady Mountains; They were wind-polished, but that was all; I thought I'd try an experiment. I put them into the 1/2 gallon tumbler, (Lortone), with tin oxide and very little water. I let them go for two weeks, picking the thing up occasionally and shaking it to see if the stones were still moving, thinking to add water if they stopped, but they never did. After two weeks of polishing without grinding, I took them out -- my test piece looked good, so I washed them all. After drying, they were the most incredibly beautiful Chalcedony Roses I had ever seen! I think the old-fashioned ways are sometimes the best, and the polish without grinding is the neatest trick I ever came up with! In Chalcedony Roses especially, Carborundum gets into the small seams, and you can't get it out! Try the stunt -- you might be amazed. Ted Robles <erobles24@hotmail.com> ________ From: Alan Silverstein <ajs@hpfcajs.fc.hp.com> Date: 1 Nov 1999 09:30:52 -0700 Subject: Re: Tumbling Questions To: les_gehman@hp.com Cc: ajs@hpfcajs.fc.hp.com > Plastic pellets > > When are they needed? Which types of rocks, and for which > stages in tumbling? Right now, she's tumbling quartz and using > pellets at all four stages in tumbling. Can the pellets be > re-used? And, if so, do we need to keep seperate the pellets > used with the different grades of grit? Ouch! Pellets with coarse => no more pellets. :-) My own experience is that I throw anything I want into coarse runs (with NO pellets). Only calcite, fluorite, azurite, and malachite, which don't tumble-polish well anyway, "evaporate" too much in one week... Now, "hard" and "soft" are in quotes because it's not literally Mohs hardness. Rather, agate, jasper, etc. are "hard", while quartz, tigereye, obsidian, etc. go in "soft" along with obviously softer stones like feldspar. Basically any stone that "frosts" rather than taking a high shine, which includes quartz because it has a different crystal structure than agate. You can learn this for yourself simply by trying to tumble quartz with agates and no pellets. I wouldn't mind always using pellets, but they're simply unnecessary for harder stones, take up capacity, and increase the hassles doing tumbler dumps. I keep one batch of pellets for fine runs and one batch (separate) for prepolish and polish (both types share same pellets). The first batch turns black, presumably from embedded grit, and the pellets are slowly being consumed. The second batch is just light gray, and seems to work fine. Yes you can reuse the pellets. Just dump the tumbler into a bowl and shake/flush that repeatedly into a strainer -- the pellets float off. I rinse and then shake the pellets in a strainer as dry as I can get them, then store them in an open container for a while until they evaporate dry, shaking every few days. The trick with prepolish/polish is to separate the pellets, polish slurry, and stones, while keeping the polish for reuse (!) Use minimum rinse water and capture the polish slurry. I used 1 gallon bottles, let settle, pour off clear water (or somewhat gray, but minimum mud goes down the drain), shake, and reuse. You lose a few pellets and a little polish slurry each time, oh well, add more polish compound as needed. > Polish step > > There appear to be a variety of different polish types. How do > we choose which type to use? Does it vary with type of rock? Yes, but I'm no expert and I don't worry about it. I buy whatever seems cheapest, still $7-15/lb for polish; prepolish is cheaper, $5/lb? Like "tripoli". Often it's simply a white powder labeled "polish compound" with no further designation. Might be tin oxide? Cerium is good stuff but is pink, and more expensive. Aluminum oxide is also good stuff, and white, but more expensive. I get good results regardless, moreso as I let the pre and polish runs go long, 8-9-10 days. ... 2. INFORMATION ABOUT TUMBLING EQUIPMENT Date: 14 Sep 1995 From: Alan Silverstein <ajs@hpfcajs.fc.hp.com> To: rocks-and-fossils@world.std.com Subject: tumblers! ...Many years ago, being cheap, I built a tumbler base out of spare parts and tried running it with beach sand as the grit. I got discouraged when the glass jar broke after a few days. What a mess. :-) I shelved the unit (literally) until about two years ago, when I discovered I could buy a real rubber tumbler barrel, 2 lb size, for about $16 from a catalog. So I did. I found some real grit by the ounce in a local rock shop, computed that the finished cost for grit added up to about $1 per pound of finished rock, and I was in business. (The number is higher now as I've gotten pickier, and tend to run longer and with more grit...) Well it worked for some months, anyway, until the home-made base gave out. It wasn't pretty. Now hooked, I ordered a real tumbler base, without a barrel, from a different company. Surprise, they sent me a base and TWO barrels, and billed accordingly, but I got that straightened out... So now I have a Lortone 2 lb single-barrel tumbler that has worked great for a year and a half; about $53 in the catalog (base + barrel :-) last time I looked. More recently I bought a VibraTek "tumbler" ($90) that holds about 3 lbs, intending to use it to do the coarse tumbling on a backlog of rocks, since that is the most time consuming step. (It took a while to figure out it could be loaded with 3 lb rather than 3 oz, that is, nearly to the top of the outer plastic bowl rather than nearly to the top of the inner rubber tub, but that's another, more embarrassing story. :-) Here's what I like and dislike about tumbling in general and these tumblers in particular. In general, I like that... * Material to tumble is easy to find, including petrified wood (in this part of the world). When sufficiently agatized, wood in particular can produce beautiful results. You can tumble stuff that has no other gem value due to its shape or size. * Tumbling usually improves most suitable rocks, making them more attractive. (Not always though.) * Running a tumbler is pretty mindless and low-overhead. * You get lots of nice rocks to give away, and they are more interesting, or at least more unusual, than the typical store-bought stuff (tigereye, citrine, hematite, you know the display). You can even do pieces big enough to become small paperweights. * Your friends and neighbors think you're a little weird and don't bother you much. :-) I dislike: * You have to be patient. Especially with coarse, hard material, it can take a month (four one-week cycles), or more, in the rotating tumbler to round it off enough to be really nice. * Some materials, even hard ones like quartz and quartzite, don't polish well, or unevenly (small chipping). Soft materials must be segregated and processed alone, too. * Tumblers are noisy, but in my house, down the basement, they're not a problem. I can hear them just well enough to know they are running OK. * I am comfortable letting them run when I'm not home, except overnight trips; then I have to go down and turn them off/on and keep track of the accumulated run time. * You can't dump the used slurry down the drain because it would clog it up. You have to dump, flush, dump... into a container that goes into the garage to settle, pour off the clear water, and dump the rest in a hole in the garden. I like about the Lortone unit: * So far it seems like it will run forever. There is very little sign of wear on the barrel or anything else in a year and a half, except maybe the O-ring between the motor and shaft (easy to replace). Oh, and some rust on the center screw on the barrel lid. * With some practice it's pretty easy to load it up properly, and to monitor it from the sound of it. * I can let it run for a week unattended. I might be able to cycle it sooner, but this way I'm sure all the grit is used up (well almost always) and that I've let it run long enough. * It takes 15 minutes or less a week to service (flush, dump, rinse, reload). More time on the rarer occasions when I sort the rocks and assemble a different load. I dislike... * It's a bit of a pain getting the lid open and resealed... But hey, it does NOT leak. :-) * Capacity is low once you do some serious collecting. Gotta be patient! Also, you can't process anything much bigger than a small plum. I like about the VibraTek... * As advertised, it is "aggressive" and fast, at least, faster than the rotating tumbler. And it holds more rock than the little Lortone. I dislike that... * The unit must be serviced about every 12 hours of operation, that is, twice a day. It only takes five minutes, but it's a drag. Dump it into a bucket, spray out and capture remaining grit, spray/roll/spray the rocks (coated with sticky gray slime), rinse rocks (don't lose the unused grit), drain well (don't lose that grit!), reload (add grit to make up a tablespoon again). * It's not THAT much faster than the rotating tumbler. It certainly takes more than the advertised 48 hours to coarse-grind rocks to an acceptable state, more like 1-2 weeks. The total labor involved is probably higher too... I'm still debating whether the money would have been better spent on a higher capacity rotating tumbler... * As documented, the plastic bucket is wearing out rapidly above the rubber insert, on coarse grit. The rubber insert looks like hell too, all scratched and abraded. * It is very sensitive to the amount of rock, water (can't use much), grit, and the vibration adjustment. Sometimes it does a lot more work in 12 hours than at other times. * The rocks don't seem to be, well, rounding? as well as they would in the barrel. Lots of facets even as they get smoother. ________ From: Alan Silverstein <ajs@hpfcajs.fc.hp.com> Date: 27 Aug 1996 19:25:56 -0600 Subject: Re: Tumblers To: rocks-and-fossils@world.std.com > Lot O' Tumbler by Calaway suits me... ... > Gemstone vibratory. I wouldn't even mess with a rotary... Since the subject has come up again, and I DO mess with rotaries and had a bad experience with the one vibratory I bought, I would appreciate elaboration from either or both of you. In particular, do these vibratories not suffer from the same problems as the Vibratek? Such as -- * Is it easy or difficult to get the right mix of rocks (and rock sizes), grit, and water to get good tumbling action? (With rotaries it's pretty easy, nearly mindless, with lots of margin for error.) * Can you let the unit run unattended for more than, say, 12 hours without getting all gummed up and then trashing the rocks? In other words: Are they demanding of attention? (With rotaries it's rarely harmful to the rocks to let them run for DAYS too long, just so you keep the rollers lubricated periodically; in fact it seems to give a better polish on the final stage if you don't get around to it for several more days after a week.) * How often must you attend to them? (Not necessarily bad if it's more frequent than weekly, like with rotaries, as long as it means you make proportionally fast progress, and no damage results if you don't get to it RIGHT NOW. With the Vibratek I found myself turning it off a lot because 12 hours had gone by, but I didn't want to mess with it twice in one day. With the rotaries I get more "continuous operation" with fewer hassles.) * How easy is it to clean the grit and slime off the rocks between loads? (With rotaries it's a bit of a mess catching the load in a collander over a bucket, but the slime rinses right off the rocks without a lot of work or water pressure. The Vibratek ran so dry that the slime was like semi-hardened concrete, a pain to clean off.) * Can you do big rocks in big vibratories? (My 12lb rotary can polish an apple-sized paperweight. Is the same true of a 12lb vibratory?) * How robust is the equipment? (The rotaries can go for years without wearing out. The Vibratek ate its bucket fast.) ________ From: Tim Fisher <tfish@teleport.com> Date: 28 Aug 1996 18:50:37 -0700 Subject: Re: Tumblers To: rocks-and-fossils@world.std.com ...I had a cheap tumbler like Vibratek. It vibrated itself apart in a year. > Is it easy or difficult to get the right mix of rocks... Never even messed with it. I just add rocks, grit, and water, and turn it on. I don't even measure the grit. ...I check it once a day. Even if it does get stuck, it has never affected the finish of the rocks. >> How easy is it to clean the grit and slime off the rocks... I don't know. I take them out back and hose them off. Just like the rotary I have (which breaks down about every other month). ...Don't let it run dry! If you do, add some Ivory Snow and water; turn it on and the coating comes off in a half hour. > How robust is the equipment? Depends on the brand. A cast iron vibratory from someone like Raytech will probably last a lifetime. Bowls on the Gemstone last over a year if you don't use coarser than the recommended 100/200 grit. Then again you can get the bowl coated with the stuff they spray on pickup beds and it will theoretically last a long time using grits as coarse as 60/90. ________ From: "John D. Utterback" <rbagate@lex.infi.net> Date: 28 Aug 1996 23:34:50 -0400 Subject: Re: Tumblers To: rocks-and-fossils@world.std.com I have been using Geosonic vibratory tumblers for over 15 years and have processed tumbled stones, cabochon preforms; and I have never worn a container out. This type of tumbler is easier to use, and also if you buy one, purchase one with a variable speed control. ________ From: Gary Brown <examine@xmn.com> Date: 28 Aug 96 07:19 CDT Subject: Re: Tumblers To: rocks-and-fossils@world.std.com I use a Mini-Sonic (tm) vibrating tumbler. It gives pretty good results, though I know it can do better. All I've got to do is figure out the right combination of times for each grade of grit. At first, I was doing to short a time (the recommended 2 days or so per grit), now that I've extended the time per grit, things are looking better. ________ From: Lapidry@aol.com Date: 2 Nov 1998 18:16:44 EST Subject: Re: Rock tumblers To: rocks-and-fossils@world.std.com ...I like the vibratory because you can finish in a week and a half what takes four weeks in a drum. I have 6 Vibratory and 3 drum (multiple barrel, really the same as 6). The drum are great for rounding, you'll run out of rock before you get a rounded stone in a vibratory. On the other hand, if I'm using it for castings or cabs, I don't want rounding and I do want the more gentle action of the vibratory. I've gotten in the habit, as another reply suggested, of specializing my tumblers. One, the biggest, gets used almost exclusively for coarse grinding, another (drum) for rounding/coarse grinding if I want that and yet another for the final polish, etc. By the time you let the drum do the rounding with coarse, the vibratory can take over for the finer steps - and save time. If I were to choose only one, it'd be a vibratory. That said, my personal choice is the Lot-O-Tumbler if you can find one -- I have three and love all three. Uncle Tom's (Tom Stockwell) -- 507-451-2254 in Owatonna, MN was the manufacturer the last I saw one. Don't see much other than Lortone Drum and Raytech Vibratory at the shows around here. I would suggest that, whatever you get, you get an extra drum/container for the polish stage and use it solely for that. Saves a lot of grief. ________ From: Roger Pabian <rpabian@unlinfo.unl.edu> Date: 1 May 1997 10:24:33 -0500 Subject: RE: Vibra-Tec To: <rocks-and-fossils@world.std.com> Both rotating and vibrating tumblers have their place in the lapidary shop. I've found that the vibrating tumblers (any brand) are often very temperamental. If the water to grit ratio is to high, all the grit sinks to the bottom, and if it's too low, the slurry cakes up like concrete. You don't want to add any detergent to the water in grinding phases either (in vibrating tumblers) as the surface tension is too low to keep the grit in suspension. Some of the rubber barrels for the vibrating tumblers are not the same hardness and the grinding action can be either slowed or speeded up because of this. Ideally, the grinding phase in vibrating tumblers is best accomplished with equal volumes of grit and water. The barrel needs to be capped to prevent loss through evaporation, and a couple of drops of water need to be added periodically to prevent the slurry from becoming pasty. For a 4 to 6 pound barrel, use about 2 tablespoons (about 20 cc) of 220 grit and 2 tablespoons of water. You can add about the same amount each day for up to about 3 days before the slurry becomes too muddy and needs to be changed. Also, the grit can cake up on the sides of the barrels in vibrating tumblers and form a gritty surface that is essentially cemented to the sides, so the barrels have to be cleaned by giving them a few solid thumps to break up this cake. If you are doing thin, flat pieces such as iris agate or things that might be fragile, the real advantages of the vibrating tumblers come into play. You can put this fragile stuff in with a load of small stones and none of it breaks, whereas the casualty rate is quite high in rotary tumblers. It is also nice to finish off stones in the vibrating tumblers. One of the best polishing compounds is a couple of tablespoons of manual dishwashing detergent (not dishwashing machine detergent) and nothing else -- in about 3 days, the stones will acquire outstanding polishes without the mess of tin or cerium oxide. ________ From: "Todd Roen" <treasure@dfn.com> Date: 5 Nov 1998 08:56:19 -0700 Subject: Rock tumblers (disregard my previous) To: <rocks-and-fossils@world.std.com> ...One advantage of a rotary tumbler is that you can upgrade cheaper. When I started out with a small Lortone unit, it did everything I needed it to do, and taught me some things about tumbling. Eventually, I decided that I needed a much larger capacity, and built a unit out of evaporative cooler parts and a used motor I picked up cheap. I bought 12 lb. Lortone drums which fit 2 across on my machine. I have 4 sets of shafts (one drive and one idler per set), and can turn 8 drums easily. The whole thing takes up little space, and cost about $50 to build (minus the drums which were about $42 each plus shipping as I recall). I only turn 3 drums presently, but can easily expand the unit economically. I like the Lortone drums, as they tend to wear well. Anyway, back to the rotational vs. vibratory, the best post I saw concerning this said to ultimately get one of each. The rotary can be used for the rough grind to get a rounded shape (if this is what you desire) and then the vibratory can be used to finish the load more quickly. The vibratory unit will not round your stones very much, but really does a nice job at polishing them largely in their original shape. When making your original purchase, consider the following: A. What size do I actually NEED? B. Do I plan on expanding if this works out well? C. What finished stone shape do I desire? D. What price range do I wish to stay within? E. Is time a significant factor when tumbling? Some final notes: The vibratory tumbler uses less grit and will save you a little there. The rotary tumblers are typically cheaper to purchase when considering two units that handle equal load sizes. ________ 9911123: Measured tumbler power consumption with a smart digital meter borrowed from Doug Baskins... PF is power factor (actual watts = V * I * PF); cost is at $0.065/KWH; actual readings shown, even though they don't add up. W-nom I-nom W-act I-act PF $$/mo VA VARS 3-pound 34 0.56 19 0.35 0.46 0.93 . . 12-pound . 0.86 47 0.76 0.50 2.17 . . both at once . 1.42 67 1.13 0.50 3.00 . . 50-pound . 4.5 256 5.10 0.41 11.90 614 560 This is with the tumblers full. Empty, the 50-pound tumbler took 210 W. For comparison: washing machine . . 412 7.84 0.43 . 933 839 canister vac . . 720 . . . . . upright vac . . 555 . . . . . For the washer this was during spin cycle. The washer used 0.299 KWH in 0.7 hours => 427 W average, with a peak of 981 W. 5. THE PHYSICS OF TUMBLING (From ajs:) Approximate inside dimensions of my Lortone 2.5lb and 12lb rotating tumbler barrels: 2.5lb: diameter 10.0cm, height 10.5cm => capacity 825cc. 12lb: diameter 17.9cm max, diameter 17.2cm min, height 19.2cm => capacity 4618cc. (The 12lb barrel has 10 faces, and I used 17.5 as the average diameter.) Actual capacity ratio: 5.60 (based on volume) Nominal capacity ratio: 4.80 (based on weight) Difference: 16.7% 2.5lb barrel, 3/4 full of water: 619g (1.36lb) 12lb barrel, 3/4 full of water: 3464g (7.64lb) Given a solid cylinder of rock of each volume, to weigh 2.5lb it would have to have a specific gravity of 1.8; for 12lb, 1.6. As you have less rock and more air/water/grit instead, the SG of the rock goes up to maintain the same "capacity" of the tumbler (at the maximum 3/4 full). I observed that when I loaded the big barrel the first time with rough rock about as full as I wanted it to be, it only held about 10lbs of rock. (14.5 lbs total, with a 4.5 lb barrel.) ________ From: Hale2@aol.com Date: 22 Nov 1995 17:57:40 -0500 Subject: Tumbler Speeds (edited, corrected) To: ajs@hpfcajs.fc.hp.com RPM(round) = 132.8 / sqrt (diameter in inches) RPM(hexagonal) = 79.7 / sqrt (diameter in inches) Or (original form): RPM(round) = 54.2 / sqrt (radius in feet) * 0.5 RPM(hexagonal) = 54.2 / sqrt (radius in feet) * 0.3 ...the name of the booklet is TUMBLER'S GUIDE, ...published about in 1960. (From ajs:) So my tumblers should run at 66.9 RPM and 30.4 RPM, respectively. Some observed numbers for barrel rotation speed: Lortone 2.5lb tumbler: 52 RPM (22% "low") Lortone 12lb tumbler: 28 RPM ( 8% "low") Thumler 12lb tumbler: 22 RPM (barrel about same size as Lortone 12lb) Based on the nominal and observed speeds and the analysis below, nominal theta for my round barrel is about 14.5 degrees, actual 8.7 degrees; and for my faceted barrel, 5.2 and 4.4 degrees. ________ From: ray@therad.rpslmc.edu (Raymond Rodebaugh) Date: 27 Nov 95 15:53:44 CST Subject: Re: tumbler dimensions, correction (edited) To: rocks-and-fossils@world.std.com There are three things relevant work here: normal force (points toward the center of the tumbler to the rock in question, it is applied by the tumbler wall), friction (points tangentially to the rim of the tumbler), and gravity (which points towards the center of the earth). The relative contributions of these three forces (primarily) determines what happens in the tumbler. In short, if the tumbler goes much too fast the rotation of the stones is dominated by the normal force and the stones stick to the tumbler walls. There is no movement of stone against stone, so no grinding is done. The normal force is always greater than gravity here. If the tumbler is somewhat slower, we now have competition between gravity and the normal force. The rocks are carried up the sides of the tumbler and dropped when the component of gravity along the radius (m*g*sin(theta)) equals the centripetal acceleration (m*v*v/r). Now if the tumbler speed is a little too fast, the rocks will be dropped when they reach the top of the tumbler. They will thus gain a significant amount of energy before they hit the rocks at the bottom, sometimes chipping. What you want is for the rocks to effectively roll/slide over those below them. If the tumbler is going too slow, the frictional force from the walls of the tumbler will be unable to overcome the force of gravity and they will stay in the bottom of the barrel. From drawing a picture to figure out the forces, I find for a round barrel: m*g*sin(theta) = m*v*v/r {or v = sqrt(g*sin(theta)*r)} where: m is the mass of the rock g is the acceleration of gravity theta is the angle between the radial line from the tumbler center of rotation to the rock and the horizontal v is the velocity of the rim of the tumbler r is the radius of the tumbler Note that the mass cancels out and that: f = v/(2*pi*r) where: f is the rotation rate of the tumbler Thus we get: f = (1/(2*pi))*sqrt(g*sin(theta)/r) Notice that for a particular theta, the rotation rate is proportional to sqrt(1/r). Plugging in the numbers, we get: f = 54*sqrt(sin(theta)/r) where r is the radius in feet. {Looks like he used g = 32 ft/sec^2 = 115200 ft/min^2.} ________ From: Hale2@aol.com Date: 28 Nov 1995 01:58:29 -0500 Subject: Re: tumbler dimensions, an addition To: ray@therad.rpslmc.edu The three forces you consider imply that the only rock being modeled is the rock at the top of the heap adjacent to the outside wall, and as such this is an idealized set-up ignoring the many interactions with other rocks. I am not suggesting you should try to set up a complicated model, but I think others on the mailing list who may not be as sophisticated in physical modeling as you apparently are should be made aware that this is a single rock simplified model of a much more complicated situation... ________ From: ray@therad.rpslmc.edu (Raymond Rodebaugh) Date: 28 Nov 95 09:35:40 CST Subject: Re: tumbler dimensions, an addition To: ray@therad.rpslmc.edu, Hale2@aol.com Cc: ajs@hpfcajs.fc.hp.com ...Yes, I did ignore the other rocks, since I think they are not too important for this problem (hence the word "primarily"). I do believe that they will only slightly increase the angle the tumbler turns before the top rock(s) roll down. They are important for holding the lower rocks in place. I also believe that I could solve the many body problem (with some simplifying assumptions on the shapes of the rocks) but would not expect a significantly different result. I also figured that, in addition to consuming at least 1/2 day of effort, the solution would be complicated enough that no one would want to read the solution. ...I am not clear where they got the 0.3 either. How does one measure the diameter of a hexagonal barrel. Is it the distance between the midpoints of opposite sides? opposite corners? or the diameter of the outer rim? 6. REALLY BIG TUMBLERS From: lapidary@mindspring.com Date: 25 Jun 99 08:33:34 EST Subject: LapDigest #215 To: LapDigest@mindspring.com ... <MSG8> Subject: RE: Large Scale Rock Tumbling I have a working knowledge of large tumblers and vibratory finishing equipment (tubs, barrels, and bowls, some of the larger stuff is well in excess of 100 cubic foot capacity). I also have experience on how to line and reline almost any type of finisher with polyurethane, and have done some work with neoprene, which would be the lining that often defines the final geometry and which lasts upwards of 10k to 30K ours of operation. One of my when "I-get-to-it projects" will be to make a mold to line the small polyethylene tubs that hobbyist use. Or even to replace the polyethylene bowl with an all urethane bowl. The basics of tumbling / mass finishing are as follows: There are several different situations. Media-on-part: Parts are finished in a moving media, which is often ceramic or plastic doped or impregnated with some type of abrasive: AlO3, SiC, silica, glass fiber, feldspar, etc. Some natural media products are also used, such as wooden shapes, walnut, coconut shell, or corncob. Media is available in many geometric shapes with various grades of cutting action. Media shapes include cones, stars, cylinders, tetrahedra, cubes, balls, trapezoidal, prismatic, free form, triangle, etc. If you can imagine a shape, it is probably available. Red Rouge is often used for the red metals, but is a royal pain because everything is sight becomes dyed red (you, your car and house, your neighbors house, your skin, etc.) Part-on-part: Often used for stampings or die cast parts, as the name implies the only things in the process would be the parts; this process uses the parts to burnish or debur each other during the process. Burnishing is typically done with hardened steel shot, die castings and the like. Think of it a peening of the surface. Different compounds can be used in the mix for cleaning, including various mixtures of surfactants, soaps, acids, alkalis, cleaners, and de-greasing agents. One of my first jobs, the owner of the company was so cheap that he used common toilet bowl cleaner for a compound. It worked, but burned like hell if you had any open cuts on your hands. And if you didn't have any, they soon developed. Compounds can and are used with all of the above. Or just plain water is often used. I consider tumbling rock to be a mix of part-on-part and part-on-media with abrasive added to speed up the action. The abrasive is kind of like a micro media. The lining materials used are typically two-part TDI polyurethane, and some of the newer technology is gearing to MDI polyurethane. Polyurethane and its application is the source of my income, if you really are interested in differences between TDI and MDI, or want to talk about an application, or need to talk about a re-line send me an e-mail. In rough terms the cost of a urethane reline can be up to $100 per gallon of urethane applied subject to mold cost if necessary. This includes sandblast and priming. Simple flat surface tumblers don't require a mold so figure a bit less. Some of the older stuff uses bonded and vulcanized neoprene, but without expensive tooling it is hard to get much more than a uniform covering for the steel below (neoprene is not my stick). Generally though urethane is superior to neoprene. In retrospect the abuse that the lining can take is truly amazing. If any one is really stuck on Neoprene I don't know of some applicators, which can do such work. I recently paid something like $100 ea. to do two small 1/2 cubic foot units, one of my quotes was $200ea for the same work, go figure. Cement mixers will work, and for the price that is not a bad way to go: $300 for the basic up to $1000 + for contractor series mixers. The user will probably want to cover the opening with visqueen and duct tape. If anyone is interested building their own large tumbler, say 10 cubic foot plus, drop me an e-mail and I can discuss the basic construction of such units. You will need access to 1/4" plate steel and means to cut it (torch or plasma) and a suitable welder (stick okay, but MIG preferred), along with the ability to work with bearings 1-1/2" dia, and shafts, possibly machined. I hope that this helps, or at least in informative. Jeff in Kalamazoo <jltford@net-link.net> +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+ <MSG9> Subject: RE: Large Scale Rock Tumbling Buy some earplugs. I don't use my 12 inch tumbler often, but when I do everyone in the house complains about the noise. It has a rubber lined steel barrel, but big rocks make big noise. I've seen tumblers made from 55 gallon drums. Two parallel shafts (about 4 inch pipe) on a 4x4 frame, one driven by a motor, and the drum rides on them (just like the little ones). Use a different barrel for each grit, and save the cost of the rubber lining by using the newer plastic barrels. It might be cheaper than converting a cement mixer as you can use salvage auto parts (drive shaft assembly) to get bearings of an appropriate size. I'm also from Michigan, and agree that we must collect gravel since the glaciers provided 20 feet or more of it over everything of interest in the area. Good luck with your project. Let us know how it came out. Kreigh Tomaszewski <Kreigh@Tomaszewski.net> +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+ <MSG10> Subject: Re: Large Scale Rock Tumbling On my last foray to Europe I met a chap in (I believe) Gelsenkirchen in Germany's Ruhr valley who tumbled stone in industrial quantities, many tons a year. The rough stage tumbler was of specially fabricated steel construction: a flattish barrel about six feet in diametre and 18" - 20" in width. It was not rubber lined, but rather lined with a special blend of concrete mixed up with silicon carbide grit in place of sand. I do not remember for certain whether he added additional coarse grit or not but think that probably he did. Medium and fine stages were tumbled in stainless steel beer barrels picked up as brewery discards and also not rubber lined. I'm not sure whether the polishing barrel was lined; I believe not. However I think he added crushed walnut shells. Cheers, Hans Durstling sinico@nbnet.nb.ca Moncton, Canada ________ From: TOM_PETTIT@HP-Corvallis-om2.om.hp.com Date: 2 Jul 1999 05:38:17 -0700 Subject: Re: FYI forward To: ajs@hpfcajs.fc.hp.com To be air tight, a split rim wheel needs an inner tube. Hah, and you thought getting rocks into a tire is hard. I'd just hang the tire on the turning shaft, tilt the whole works slightly back so it won't wander off the shaft, and let 'er rip. ________ From: lapidary@mindspring.com Date: 04 Oct 1999 09:22:07 -0700 Subject: LapDigest #236 To: LapDigest@mindspring.com <MSG5> Subject: Home-Built Tumbler I spent a little while doing your avoided search out of curiosity because I have made several tumblers and wanted to see what other's looked like. I gave up after a while and decided to answer your question myself... Our goal is to rotate a cylindrical container containing rocks, water, and grit/polish (working thru a series of grits/polishes with cleaning between) to bring the rocks to a high polish. Rubber lined containers are probably the best. Plastic can be used. With metal containers you probably need one for each grade of grit/polish to avoid grit/polish grade contamination. The classic tumbler rests the barrel on two revolving shafts, one driven, one free. The rotation of the driven shaft revolves the barrel, which then drives the free shaft. A motor is pulley/belt connected to the driven shaft. The power train -- motor RPM, motor pulley/shaft pulley ratio, shaft to barrel ratio -- causes the barrel to rotate at an appropriate speed; a four inch barrel rotates 50-100 RPM, bigger barrels more slowly. I suggest keeping towards the slower end of the range. Start by finding a barrel. The widest part of the outside needs to make a cylinder. Narrower in the middle (wider top and bottom) is ok if it is the same size cylinder at the ends. Get a motor, wire, plug, and switch so you can hook it up, plug it in, and start or stop the motor. Visit your hardware store and get four bearings that can be surface mounted and two matching shafts at least 4 inches longer than your barrel; 3/4 or 5/8 inch diameter shaft works. Get a couple of V-pulleys for the shafts -- 2 1/2 inch for one and 8 for the other is a good guess with a 1750 RPM motor, 5/8 shaft, and 10 inch barrel. Pick up a belt long enough to connect half the barrel diameter plus half the motor diameter. Pick up nails, screws, etc to put it together. Stop at your local lumber yard and get a couple 2x4s twice the diameter of your barrel. Pick up a couple sheets of plywood; one twice the diameter of your barrel X the length of your barrel cylinder plus about 4 inches, and one the diameter of your barrel X the length of your barrel cylinder plus about 4 inches. Lay down the big sheet of plywood, set the 2x4s along the sides, and lay the small sheet of plywood across one end of the top. The barrel should fit on the other half and just slide between the 2x4s. Fasten it together. Mount the motor on the top of the small plywood sheet with the shaft hanging off one side. Mount the two shafts about 3/4 barrel diameter apart on the other half of the top with bearings on the 2x4s; the drive shaft should extend past the edge the same length as the motor shaft and on the same side (and be the shaft closer to the motor). Big pulley on the drive shaft, small one on the motor, and the belt connecting them should be fairly tight. Connect both shafts together on the opposite sides with the same size pulleys and a belt if you want them both to drive. Hook up the motor, put on the barrel, and start tumbling. I'm leaving the description of another type of tumbler, the 45 degree single shaft tumbler, for next time. Kreigh Tomaszewski Mailto:Kreigh@Tomaszewski.net ________ From: lapidary@mindspring.com Date: 11 Oct 1999 13:21:35 -0600 Subject: LapDigest #238 To: LapDigest@mindspring.com <MSG8> Subject: RE: Home-Built Tumbler In my first post I covered the traditional tumbler that has the barrel rolling on its side supported on shafts that support and drive it. This posting will cover the more difficult 45 degree tumbler. With this tumbler you can use an open top barrel making it great for schoolrooms (add some Plexiglas guards over the moving parts for safety in a classroom). In this type of tumbler the shaft is attached to the bottom center of the barrel, and the barrel and shaft as a unit are tipped to a 45 degree angle, shaft down - open top of barrel up. The shaft is supported by a base block. The motor shaft has a small wheel on its end that rides on the bottom outside edge of the barrel to drive it. It can be made to spin faster by moving the drive wheel closer to the center of the barrel bottom or enlarging the size of the driving wheel. The barrel and shaft are really a single unit. For a small tumbler you could use a large plumber's helper (plunger) - the type that is shaped like a wine glass instead of a cereal bowl. For a big tumbler a steel shaft with a floor flange on one end, a circular plate attached to the floor flange, and the barrel base attached to the top of the plate. Fastening a holder (large bucket?) container that your bucket just fits into on the top of the plate is an easy solution and makes the barrel removable for cleaning. The plate will be used as the drive surface. For the plunger you need a washer shaped plate and a floor flange that you can slide down the handle and fasten on. It is important that the drive plate be at right angles to the drive shaft and be rigidly attached (and thick enough not to flex) - plywood works. Get a motor, wire, plug, and switch so you can hook it up, plug it in, and start or stop the motor. You need to be able to fasten a small wheel to the end of the shaft. Alternately, the wheel can be on one end of another shaft that is pulley/belt driven by the motor - and this actually helps since most motors you will find are probably a little fast unless your drive plate is larger than the barrel by a few inches. The drive wheel and the plate make a pulley system, so you can figure a reasonable speed ahead of time and make your drive plate large enough, or reduce the speed with pulleys by using drive from the second shaft. The end of the barrel shaft is going to support weight and needs a thrust bearing. The top end of the shaft can use a regular bearing. If you are making the plunger type you might be able to do without a bearing if you drop a large marble or ball bearing in the support hole before putting in the shaft (and lubricate the shaft with bar soap). Make sure the barrel shaft is long enough to support the barrel weight; its a lever and probably should be near the height of the barrel. We're going to need a large cube of wood. Your shaft will need to be about the length of the diagonal of a face. Stacked 4x4s with side bracing can be used in place of a block of wood. For something large, you might want to use a concrete base with a 4x4 imbedded where the shaft will go. This base block will be fastened to one half of a board twice as long as it is wide (and at least as wide as the support block). The barrel will hang over the part of the base not covered by the block, which is there to keep the whole thing from tipping over. With the base assembled, the shaft/barrel assembled, and a motor we're ready to put it together. One side of the cube rises up from the base at its center. At the top center of this edge we're going to drill a hole 45 degrees downwards to the center of the bottom edge that is at the outside of the base. Don't drill all the way thru if making a plunger tumbler and make sure the shaft just fits the hole; otherwise drill a hole large enough for the shaft, mount the bearings (thrust bearing at the bottom, regular bearing at the top), and line them up with the shaft. The drive plate should be a little ways above the block when the shaft is inserted. If you are not using bearings, make sure the hole is smooth and closely fits the shaft - drill a smaller pilot hole first. Mount the motor so that the wheel on the end of the drive shaft pushes up against the bottom of the drive plate at its edge. The axis of the drive shaft on the motor should point at the center of the barrel shaft. As the drive wheel turns, friction against the base plate makes it turn. Hook up the motor, put on the barrel, and start tumbling. Don't fill your barrel too full or it will splash out the top. If the barrel has a small neck, like a wide mouth mason jar, that is a good thing. Kreigh Tomaszewski Mailto:Kreigh@Tomaszewski.net ___________________ New material to merge: ADVICE ON GRITS (EDITED): From: John McLaughlin <jemstone@amug.org> Date: 22 Apr 2003 13:15:53 -0700 Subject: Re: [The Rockhounds List] Polishing compounds [edited] To: RockhoundsList@yahoogroups.com LINDE A AND B are trade names for CORUNDUM (sapphire/ruby powder). The A is 0.3 micron in size and the B is 0.05 micron. Alumina is often used as a name for ALUMINUM OXIDE. Aluminum Oxide is corundum. All the same. I have not used the 0.05 micron size, but I do use the 0.3 micron powder as an additive to CERIUM OXIDE. Also, a small amount of the 0.3 micron alumina in a tumbling polish mix will produce mirror like polishes on quartz family stones. I have polished ruby in zoisite (two separate minerals). The green zoisite will polish just fine with aluminum oxide. However, ruby is aluminum oxide. To really get a great polish on the ruby you have to use diamond. You can't hurry any of the steps and you can't make big jumps in the grades. Final polish of 100,000 diamond will produce a great looking piece, but the time involved is enormous. The best polish on ruby in zoisite I have seen was done by Thomas Harth Ames (winner of the AGTA Cutting Edge Award Best of Show for the year 2000 for an Oregon opal carving). When I asked him how he achieved a mirror polish on the ruby in zoisite, his response was animated, not entirely printable and carried the strong conviction that he would never undertake that kind of job again. The number of hours he put into the slow polishing process convinced me to wind up my ruby in zoisite piece with less than an ultra high shine. ... ______________ From: "evanchugg" <evansite@paradise.net.nz> Date: 24 Apr 2003 12:13:13 -0000 Subject: [The Rockhounds List] Re: Polishing compounds To: RockhoundsList@yahoogroups.com The LINDE A/B and ALUMINIUM OXIDE should be classed as CORUNDUM -- sapphire is gem-grade corundum, as is ruby. Your "off-white" pre-polish sounds rather like cerium oxide or a mix of cerium and another oxide, while the "white" polish sounds like tin oxide. TRIPOLI is IRON OXIDE (= rust, really!) and while it was used a lot in the past, it seems to have gone out of favour. I think it may be better used on a buff, rather than in a tumbler. I would suggest CERIUM OXIDE for pre-polish, TIN OXIDE for polish, in the tumbler. Most local people skip the pre-polish stage and go straight to tin oxide polish, with good results. A number of people on the late, lamented Rocknet board told how they run only coarse grit in the grinding stage, relying on the silicon carbide breaking down into finer and finer grit, rather than cleaning out and putting in new, finer grit. Not something I've tried myself, but they seem to be happy with their results. I know that several of our Club's top carvers of nephrite jade never use anything finer than 600 grit wet-and-dry paper - which they back with plastic parcel tape to reinforce the paper - but jealously guard their worn paper as the grit breaks down to give a finer and finer surface, and claim it works at least as well as 2000 grit paper. ______________ From: Jim <jsmall47@earthlink.net> Date: 24 Apr 2003 08:45:00 -0400 Subject: Re: [The Rockhounds List] Re: Polishing compounds To: RockhoundsList@yahoogroups.com TRIPOLI's main abrasive ingredient is silica. Some formulations have included iron oxide, but the primary work is done by fine-particle silica. JEWELERS ROUGE, in powder form, is pure iron oxide, and is used as a final polish, for tumbling or buffing. Tripoli is never a final polish, excepting for some ferrous metals, and then it is applied as a paste to buffs for polishing. I have used tripoli powder for a pre-polish for quartz gems, but I prefer 600 grit SiC. ______________ From: fossilnut@aol.com Date: 24 Apr 2003 15:41:46 -0400 Subject: Re: [The Rockhounds List] Re: Polishing compounds To: RockhoundsList@yahoogroups.com Another white powder final polish I've used is TITANIUM DIOXIDE. I forget what size range I had but I had about a gallon container of the material and it worked very well on most stuff. ______________ From: John McLaughlin <jemstone@amug.org> Date: 27 Apr 2003 21:59:02 -0700 Subject: Re: [The Rockhounds List] cheaper polish compound? To: RockhoundsList@yahoogroups.com ...I would suggest you get in touch with LOU IRONS of Lou Irons Lapidary http://www.lapidarysupplies.net/ Lou is over 80 now with a very long life time of experience in all phases of lapidary. He works from his home and does a few shows with a partner and has forgotten more about lapidary than most folks ever learn. He has fair prices for his materials, but more than that, he can help you problem solve your tumbling polish issue. I use a "SUPER CERIUM" oxide from Lou that is white, not pinkish. The color in cerium oxide is iron oxide and indicates problems with purity. I mix it with a small amount of Lou's generic "Linde A" corundum powder and get mirror results from tumbling. It does not take much of either and is very cost effective. ($22/lb super, $9/lb regular) ______________ From: "Brian Jackson ( Cyberrockhound)" <cyberrockhound@cableone.net> Date: 28 Apr 2003 08:23:27 -0500 Subject: polishing compound To: <ajs@frii.com> http://www.cyberrockhound.com/Lapidary_Polishing_Powders.htm Best buy on polishing compounds! (nope, $14/lb tin, $9.25/lb rapid) ______________ From: r2d2ooooo@aol.com Date: 28 Apr 2003 10:15:40 EDT Subject: Re: [The Rockhounds List] cheaper polish compound? To: RockhoundsList@yahoogroups.com I recently bought some (TIN OXIDE) from a supply place in Georgia for, I think it was 8 or 9 dollars a pound. This was my first time to buy it and I have not used it yet. I bought a couple grades of silicon carbide form them for less than any place that sold lapidary equipment. There are a lot of granite stone quarries in Georgia and these supply houses sell to that trade. Everybody check them out. I called the 1-800 number and they shipped to me. I can't remember all the prices but they beat everybody else and believe me I searched far and wide. If you have industrial suppliers of this type in your area you might get it and save on the shipping. "http://www.milessupply.com/">Welcome to Miles Supply's Web Site (Huge quantities, no prices, wrote to them, no reply.) ______________ From: "Brian Jackson ( Cyberrockhound)" <cyberrockhound@cableone.net> Date: 28 Apr 2003 11:33:53 -0500 Subject: RE: polishing compound To: "Alan Silverstein" <ajs@frii.com> ...RAPID POLISH -- WORKS EXCELLENT. Its a micro ALUMINA powder that is a platelet and not a crystal which is why it works so well especially on Jade, Petoskey stones, obsidian, Lapis. Doesn't work well on some soft stones like turquoise. From: Alan Silverstein Date: 10 Jan 2005 13:48:44 -0700 Subject: Re: big tumblers... To: quappelle@cox.net I don't think I told you about buying grit. The tire tumbler eats grit fast. As I wrote in my webpage, at least for coarse grinding the grit is "just" an accelerator. I've actually tried running the tire tumbler for the usual time, four days, with rocks and water but no grit. The rocks do grind a little, and a weak slurry is produced, but it's perhaps five times slower than using grit. You know you're serious about a hobby when you buy supplies a hundred pounds at a time and congratulate yourself on saving money. (grin) And, I literally do. More than once a year I order 100 lbs of 30-grade SiC grit, most recently from Eloxite in Wyoming, for about $1.49/lb delivered to my door. I decant it from bags-in-boxes to a covered bucket. When I load the tire tumbler, I add over a cup of grit, nearly 2 lbs. Two days later it's pretty much gone, if you feel the slurry, there's no coarseness to it. So I open and clean the door, add another cupful, and run two more days. After that the slurry gets thick enough that it's time to dump the load (that is, once every four days), and wash and sort the rocks. A typical rough agate takes 2-3 runs or 8-12 days to get nice and smooth for polishing. I figured out a while ago that at $149 for 100 pounds, I use up grit at about the rate of $1.25/day. Now, the motor on the tumbler eats about 250 watts, or about 6 KWH/day, or about $0.40 for electricity (just a guess). ------------------ From: Alan Silverstein Date: 10 Jan 2005 15:43:03 -0700 Subject: Re: big tumblers... To: quappelle@cox.net > I can also tell you some stuff (and even show some pictures if you > want) about the process of replacing the tire; what it looks like when > they leak (UGH); how fast they eat SiC grit; how fast they run (and > thus how many miles you get out of them); and why you can't actually > do this in your family truck -- which is a very common response, as > you wrote in your column. I think I've now covered most of this -- what leakage looks like (you saw the picture on the web, right?), eating grit, run speed and "distance", and family truck. OK, lemme tell you about replacing the tire. First you gotta score a new used tire. You don't care how much tread is left on it, but it's good if, unlike my second one, it lacks any cuts in the sidewalls or other punctures, otherwise you have to seal the holes somehow. (Epoxy seems to work.) Getting a replacement tire usually means begging one from the recycle pile behind your local favorite tire dealership. Unfortunately my main connection no longer lets me take away tires, even dead ones, "insurance reasons" they say. Other places have been more friendly, or even apathetic. Good thing, these big tires are so expensive, like $80-100 each, you wouldn't want to have to pay for new ones for this purpose. You gotta catch the tire dealership when their pile is accessible and when it contains a juicy-looking tire of the right size. When you are hunting for a 33x10.5x15 (which is what I built my base to handle), forget it, they're too rare. After I wore out the first one, I had to give up and downsize to 31x10.5x15. These are still big enough that they use English for all three units, not just the last one (wheel diameter), but they're easier to find. Ironically, my spare vehicle, a Toyota truck, wears 31x10.5x15 tires that are just begging to become tumbler barrels someday. However, at the rate I put miles on the truck, I'll never need to replace them... Next, when you're ready, I'll tell you about moving the door plates from the old tire to the new one, disposing of an old tire, and how doorstops and hockey pucks play an important role in the process. That reminds me, I can also describe my disastrous attempt to line a tire with used conveyor belt... ------------------ From: Alan Silverstein Date: 18 Jan 2005 22:25:36 -0700 To: ajs@frii.com ADVICE ON GRITS (EDITED): From: John McLaughlin Date: 22 Apr 2003 13:15:53 -0700 Subject: Re: [The Rockhounds List] Polishing compounds [edited] To: RockhoundsList@yahoogroups.com LINDE A AND B are trade names for CORUNDUM (sapphire/ruby powder). The A is 0.3 micron in size and the B is 0.05 micron. Alumina is often used as a name for ALUMINUM OXIDE. Aluminum Oxide is corundum. All the same. I have not used the 0.05 micron size, but I do use the 0.3 micron powder as an additive to CERIUM OXIDE. Also, a small amount of the 0.3 micron alumina in a tumbling polish mix will produce mirror like polishes on quartz family stones. I have polished ruby in zoisite (two separate minerals). The green zoisite will polish just fine with aluminum oxide. However, ruby is aluminum oxide. To really get a great polish on the ruby you have to use diamond. You can't hurry any of the steps and you can't make big jumps in the grades. Final polish of 100,000 diamond will produce a great looking piece, but the time involved is enormous. The best polish on ruby in zoisite I have seen was done by Thomas Harth Ames (winner of the AGTA Cutting Edge Award Best of Show for the year 2000 for an Oregon opal carving). When I asked him how he achieved a mirror polish on the ruby in zoisite, his response was animated, not entirely printable and carried the strong conviction that he would never undertake that kind of job again. The number of hours he put into the slow polishing process convinced me to wind up my ruby in zoisite piece with less than an ultra high shine. ... ______________ From: "evanchugg" Date: 24 Apr 2003 12:13:13 -0000 Subject: [The Rockhounds List] Re: Polishing compounds To: RockhoundsList@yahoogroups.com The LINDE A/B and ALUMINIUM OXIDE should be classed as CORUNDUM -- sapphire is gem-grade corundum, as is ruby. Your "off-white" pre-polish sounds rather like cerium oxide or a mix of cerium and another oxide, while the "white" polish sounds like tin oxide. TRIPOLI is IRON OXIDE (= rust, really!) and while it was used a lot in the past, it seems to have gone out of favour. I think it may be better used on a buff, rather than in a tumbler. I would suggest CERIUM OXIDE for pre-polish, TIN OXIDE for polish, in the tumbler. Most local people skip the pre-polish stage and go straight to tin oxide polish, with good results. A number of people on the late, lamented Rocknet board told how they run only coarse grit in the grinding stage, relying on the silicon carbide breaking down into finer and finer grit, rather than cleaning out and putting in new, finer grit. Not something I've tried myself, but they seem to be happy with their results. I know that several of our Club's top carvers of nephrite jade never use anything finer than 600 grit wet-and-dry paper - which they back with plastic parcel tape to reinforce the paper - but jealously guard their worn paper as the grit breaks down to give a finer and finer surface, and claim it works at least as well as 2000 grit paper. ______________ From: Jim Date: 24 Apr 2003 08:45:00 -0400 Subject: Re: [The Rockhounds List] Re: Polishing compounds To: RockhoundsList@yahoogroups.com TRIPOLI's main abrasive ingredient is silica. Some formulations have included iron oxide, but the primary work is done by fine-particle silica. JEWELERS ROUGE, in powder form, is pure iron oxide, and is used as a final polish, for tumbling or buffing. Tripoli is never a final polish, excepting for some ferrous metals, and then it is applied as a paste to buffs for polishing. I have used tripoli powder for a pre-polish for quartz gems, but I prefer 600 grit SiC. ______________ From: fossilnut@aol.com Date: 24 Apr 2003 15:41:46 -0400 Subject: Re: [The Rockhounds List] Re: Polishing compounds To: RockhoundsList@yahoogroups.com Another white powder final polish I've used is TITANIUM DIOXIDE. I forget what size range I had but I had about a gallon container of the material and it worked very well on most stuff. ______________ From: Dale Rhode Date: 27 Apr 2003 21:25:09 -0700 Subject: Re: [The Rockhounds List] cheaper polish compound? To: RockhoundsList@yahoogroups.com ...Eloxite has TIN OXIDE for $10.95 a lb and RAPID POLISH for $8.75 a pound. Here's their link, http://www.eloxite.net/ OR http://www.creditcardcastle.com/cgi-bin/template.cgi (yup!) ______________ From: John McLaughlin Date: 27 Apr 2003 21:59:02 -0700 Subject: Re: [The Rockhounds List] cheaper polish compound? To: RockhoundsList@yahoogroups.com ...I would suggest you get in touch with LOU IRONS of Lou Irons Lapidary http://www.lapidarysupplies.net/ Lou is over 80 now with a very long life time of experience in all phases of lapidary. He works from his home and does a few shows with a partner and has forgotten more about lapidary than most folks ever learn. He has fair prices for his materials, but more than that, he can help you problem solve your tumbling polish issue. I use a "SUPER CERIUM" oxide from Lou that is white, not pinkish. The color in cerium oxide is iron oxide and indicates problems with purity. I mix it with a small amount of Lou's generic "Linde A" corundum powder and get mirror results from tumbling. It does not take much of either and is very cost effective. ($22/lb super, $9/lb regular) ______________ From: "Brian Jackson ( Cyberrockhound)" Date: 28 Apr 2003 08:23:27 -0500 Subject: polishing compound To: http://www.cyberrockhound.com/Lapidary_Polishing_Powders.htm Best buy on polishing compounds! (nope, $14/lb tin, $9.25/lb rapid) ______________ From: r2d2ooooo@aol.com Date: 28 Apr 2003 10:15:40 EDT Subject: Re: [The Rockhounds List] cheaper polish compound? To: RockhoundsList@yahoogroups.com I recently bought some (TIN OXIDE) from a supply place in Georgia for, I think it was 8 or 9 dollars a pound. This was my first time to buy it and I have not used it yet. I bought a couple grades of silicon carbide form them for less than any place that sold lapidary equipment. There are a lot of granite stone quarries in Georgia and these supply houses sell to that trade. Everybody check them out. I called the 1-800 number and they shipped to me. I can't remember all the prices but they beat everybody else and believe me I searched far and wide. If you have industrial suppliers of this type in your area you might get it and save on the shipping. "http://www.milessupply.com/">Welcome to Miles Supply's Web Site (Huge quantities, no prices, wrote to them, no reply.) ______________ From: "Brian Jackson ( Cyberrockhound)" Date: 28 Apr 2003 11:33:53 -0500 Subject: RE: polishing compound To: "Alan Silverstein" ...RAPID POLISH -- WORKS EXCELLENT. Its a micro ALUMINA powder that is a platelet and not a crystal which is why it works so well especially on Jade, Petoskey stones, obsidian, Lapis. Doesn't work well on some soft stones like turquoise. ______________ From: "Jeff Salvador" Date: 28 Apr 2003 13:36:40 -0400 Subject: To: Alan, we retail the Vertex Tin Oxide for the following prices: $ 13.90 per lb. 1 - 25 lb. quantities $ 9.25 per lb. 26 - 99 lb. quantities $ 5.25 per lb. 1 100lb. drum + Our minimum quantity is 1 lb. (Declined, Eloxite is cheaper.) ------------------ From: Alan Silverstein Date: 18 Jan 2005 17:27:53 -0700 Subject: Re: big tumblers... To: quappelle@cox.net I wrote previously, ...I'll tell you about moving the door plates from the old tire to the new one, disposing of an old tire, and how doorstops and hockey pucks play an important role in the process. That reminds me, I can also describe my disastrous attempt to line a tire with used conveyor belt... Here goes on door plates... In the beginning, I had two big wooden disks, one for each side of the tire, with a long threaded rod through their centers to hold them together by force. Each door plate was really two concentric plywood disks, one a bit smaller than the other, glued and screwed together to make a stepped outer edge. The smaller disk was 15" across and went inside the bead, while the larger one rested against the bead. There was weather-stripping on the outer disk edge against the bead. The rear door tended to "glue" itself onto the backside of the tire, which was good. However, both doors tended to warp and leak from the edges over time. Eventually I gave up on this design. I filled the center hole in the rear door, and I made a new front door that's pictured in the photos you've seen. It's still two concentric disks, stepped on the outer edge, but also with concentric center holes, stepped the opposite way. A smaller disk (the real door) fits into the center hole. The new, smaller door disk is held in place against the outer plate at four points with big plastic wingnuts salvaged from old mower handles. The new inner door disk still has marine/RV weatherstripping on its outer edge, where it goes against the disks. I have to replace it every 3-4 months as it compresses to where it no longer seals. Now when a tire wears out on the inside, I have to remove the doors from it, clean them up, and put them back on a new tire. This takes 2-3 weeks. Why? I repaint the door plates if/as needed with marine enamel (boat-bottom) paint, put new weatherstripping on them, and screw them onto the new tire's bead with silicone caulk gushing out. Then I let the caulk dry thoroughly for at least a week. (It still fails sometimes.) Using deck screws to hold the doors to the tire is surprisingly difficult. In many cases they just don't want to bite into the steel belts inside the bead rubber. The next time I replace the tire, which will be soon, I'm considering replacing one or both doors with new parts made from a big scrap sheet of nylon I scavenged... It's about like cutting board material. We'll see. At least it would not need painting and would not warp. ------------------ From: Alan Silverstein Date: 16 Feb 2005 13:23:13 -0700 Subject: Re: big tumblers... To: quappelle@cox.net Hockey pucks are already dirt cheap. :-) They're about $1.25 at a local sporting goods store. I use them to make speed bumps inside the tire. I tried rubber doorstops first, but they are hollow and don't last that long. I use three deck screws per puck, through the outside of the tire, between the treads, into the puck, to hold it in place. The screws stick out into the center of the tire, but it doesn't matter, they wear off quickly. The pucks ensure that the rocks get stirred and don't just slide along. This helps the gentle but continuous grinding motion. A pair of pucks usually outlasts one tire. They get rounder and smaller... Sometimes they bust right off, but the screw heads remain and the holes seldom leak. Now, did I tell you about disposing of used tires? ------------------ From: Alan Silverstein Date: 18 Jun 2005 18:10:30 -0600 Subject: Re: Another rock tumbling question. To: hugh@wiredvideo.com Cc: ajs@frii.com Hugh, > Hi again! Found myself back on your pages checking to see if I'm > doing stuff right or not. (grin) > Just realized that my barrels need to be 1/2 to 3/4 full, not "up to > 1/2 full" as I thought I'd read, haha. Well, it might not hurt anything, or it might be more violent, but anyway it wastes capacity. > Anyway, have you ever heard of someone using just plain beach sand for > tumbling? Sure, I've tried it myself, and I get asked that question now and then. The main thing is that sand is just quartz (usually) and it's not as hard as SiC => wears out faster and doesn't do as much grinding. I wrote about how the grit is really just an accelerator, but a big one, but of course it costs more. It amazes me that even SiC is reduced to mud in 2-4 days in my tire tumbler. I suppose if you are patient enough and don't mind the extra run time on your equipment, beach sand or nothing at all is OK, and saves money and effort. > So far my process has been: > > 1. Tumble with just water to remove very rough edges/break rocks that are > going to break, anyway. And that works, right? But still, grit should be faster. > 2. Drill holes in the rocks that show some promise as a nice necklace. > 3. Put the drilled rocks back into tumble with coarse grit to further round > them a bit and remove any imperfections introduced by the drilling (such as > bad breaks on the opposite side of the drill bit). Yup, that should work. Of course one risk is getting tiny stones stuck in your drill holes. I'm always prying pebbles out of cracks, using a dental pick. > I haven't yet gotten to the point where I'm actually polishing rocks (which > will be my next step with one of my loads), but, I've been thinking about > beach sand. How "hard" is beach sand compared to, say, a coarse grit? Beach sand is just another kind of rock. Best you can hope for is it speeds up grinding just a little because it creates more contact area. Quartz is 6-7 I think, and SiC is 9? > Thanks again for the great site. Hoping I can contribute (particularly about > the possibilities of shining stones that have holes drilled in them, which > is looking like it should work -- we'll see after the actual polishing > steps). Sure, send me text I can edit into place, and lemme know if you want me to attribute to name + email, name only, or anonymous. I should add some of this reply to the site too. > Another thing I'm doing (you might cringe here) is taking a load of > rocks I've made by breaking larger stones... I've seen videos that show busting up rocks with hammers to make tumbling material. I only cringe at the idea in case it creates cracks that ruin the stone in some way. But sometimes I do pre-break or trim a stone first myself... Often using a sledge hammer and cold chisel, instead of a rock hammer, to control the force. > ...and using that black, crystalline stuff they use in outdoor > ashtrays for speedier breakdown/rounding. I bet that's just volcanic ash grit, probably as hard as beach sand. > I'll let you know what happens with that, too. Obviously, I'm not > just tumbling for the polish. :D The experimentation is fun, though. You bet! It takes time, so it's a tradeoff with "production runs", but enjoyable. How long does sand or ashtray filler last in the tumbler? Not as long as SiC I bet. ------------------ From: Alan Silverstein Date: 9 Nov 2005 22:33:01 -0700 Subject: Re: Stone size capacity (via rock tumbling webpage) To: waters@ihot.com > I have read the saga of your wonderful 50# tumbler and hope soon begin > building one of my own. Oh NO, what have I DONE? :-) Are you SURE you want to go there? Note, while originally using a 33" tire (hard to find now) I really did load the grinder with 50 lbs of rock (weighed it first). Now, using a 31" tire (I'm on my fifth tire), it's pretty full and heavy with about 2 gallons of rock (say 30 lbs?), 1 gallon of water, and 1 cup of coarse grit. However, the output from the grinder is still 2-3x the combined finishing capacity of my 12 lb + 3 lb Lortone barrels (at 3 weeks per batch, 1 week per grit). It's at the point where I'm sorting the rocks ready to polish into high priority, low priority, and "give them away" (unpolished!) I have 8+ buckets of 5 gallons each, presently full of "rocks ready to polish." > My objective is to build a tumbler that will polish volley ball size > stones. Good luck! It's a nice fantasy. I don't do anything bigger than about baseball size, mostly 'cause I'm limited by the 12 lb Lortone barrel I use for fine through polish runs. But, my experience even with that size (dunno if I wrote about it) is less-than-optimal because the coarse grinder is rough enough to leave some rough edges and crescent-shaped impact fractures in the stones, mainly in the bigger ones. I don't think I'm running it too fast, I think it's inherent in the size of the "barrel" (tire) and the drop-distance each rock experiences as the tire revolves. In other words, I don't think it scales up well. Bigger, heavier stones are harder to tumble-polish well. It might require careful loading, slower running (more time), and/or buffering of some kind, which I haven't been willing to do. (My tire runs at about 8 sec/revolution.) > Do you think your design would work? Beyond that, sure. Bigger tire, motor, -- Those should scale up. > With one, two or three large stones and a lot of smaller one for the > large ones to roll and grind on? In general I always use a mix of sizes in any load, yes. > What would you guess the largest stones would be that your design > could accommodate; volleyball, softball, hardball, smaller? Depends really on the polish barrel size. I can put rocks in the tire that are bigger than I can polish, but I don't. Also, big rocks beat the heck out of smaller ones, tending to bust them up, rough up the edges, etc. Oh, once I cleaned out the tire pretty well and tried using it for fine grinding. Then I polished these stones in the smaller Lortones (skipping fine grit, with prepolish and polish only, two weeks). I didn't get a very good result -- it was as if the tire just was too rough to smooth the rocks well even with fine grit. I gave up and resigned myself to using the tire as a grinding machine only. > I envision using a hand held grinder and disk sander to trim the high > spots in order to hasten the polishing process. In fact, I've already > been doing this and have even worked one to a fine polish using a > buffing wheel and jewelers rouge for the final operation. Sure, that part makes sense. Although I don't bother, I just run some rocks longer if I want them rounder -- where in the coarse grinder, longer might be 4-5 runs of 4 days each. Not really long. ------------------ From: Alan Silverstein Date: 10 Nov 2005 11:09:23 -0700 Subject: RE: Stone size capacity (via rock tumbling webpage) To: waters@ihot.com > "Is that any help?" Gawd I didn't expect you to write a book for me. (;>) I type fast and I'm an extrovert. :-) > Thank you, it is a tremendous help and probably has saved me a lot of > time and aggravation. Cool. The tire tumbler has been a real workhorse, but also as with any prototype it's required continuous tuning, tinkering, and repairing. And that's beyond simply replacing tires as they start to wear out on the inside and emit small, sharp metal (belt) strands. > I have always collected "pretty" rocks but only recently, the last > several years, have I been dreaming of tumbling some large stones. OK. Have you ever played with tumbling at all, smaller ones, to get an idea of the process, mess, etc? > I have a friend who bought about 100 acres of gold dredge tailings... > He's making money off of the property anyway as he discovered that > rainbow trout grow big and fast in the cold, food rich water. Yikes! Trout laden with heavy metals? I'm amazed they survive at all, much less do well, in mine tailings. But... Dredge means river gravel I guess... No residual heap-leach chemicals if they used mechanical separation methods? > He now digs holes (20 ft deep, multi-acre ponds) in the tailing to > create ponds for the trout to grow and fishermen to pay to catch. > They pay $150 a day to catch and release the monster rainbows Fly > fishing with barbless hooks only. That's amazing! Must be rich clientele. > Check'm out at www.sugarcreekranch.com to see the ponds and tailing. Quick look... Amusing. > Anyway, when I visit Sugar Creek I do a little fishing but spend a lot > more time rock hounding on the piles and piles of river rock. Nice! Assuming the gravel in this area contains interesting rocks, which it sounds like it does. > I have found several gem quality (translucent)volleyball size > specimens, so that's where my desire to polish the large stones comes > from. Gotcha. Are these agates? Biggest agate I ever found was about 10-12" across, near Hanksville, UT. Rough-rounded from some ancient river. Too big for ME to tumble, so it's in my rock garden. > Alan, what you said about the tumbler speed, the size of the tire and > the drop distance causing possibly unsolvable problems makes me wonder > if an outlandishly large circumference tire (or similar found object) > might resolve these problems. I gonna do some noodling on this and if > I can't come up with a solution I think I will forget the idea and > realize that it was, as you suggested, just a dream. OK, have fun. I suspect the answer involves a low circumference speed such that the rocks don't slide too far (building up damaging energy) when they break loose. But, picture an unstable hillside about to landslide -- you must get to a certain angle (sensitive to many factors involving the size and roughness and weight of the stones) before they let go. In a small tumbler they just can't go very far, and the action is nearly continuous. In a bigger tumbler the wall radius is necessarily lower => each landslide can fall farther. I can even HEAR this in my tire tumbler, sometimes it makes a kind of a "crash" sound and jerks visibly, in cases where apparently the rocks went up the wall more stable than usual until they finally broke loose. Maybe the answer is a whole different paradigm. Still avoiding hand-polishing (where the rock stands still and you move around it), but something that spins/rolls the stone in place. Sounds like a sphere-making machine, except you don't care if it's a perfect sphere. Do you know much about those? They have their biggest problems when the stones are rough-cut and just starting to get rounder... They don't want to rotate evenly, etc. Or I wonder if you could get good grinding and polishing in a big tire where the volleyball rock was the ONLY stone present, along with water and grit (and hockey pucks still screwed inside the tire as mixers); no impacts, just lots of rolling. I'm temporarily out of rocks to grind (less than a full load anyway), so maybe I should try this for a few days on my biggest, baddest rock that still fits in the tire. ------------------ From: "Criss Morgan" Date: 25 Jan 2006 18:18:12 -0600 Subject: [The Rockhounds List] Re: Vibrating Tumbler To: A vibrating tumbler will not round the rocks that you put in it. Instead it maintains the original shape with just a rounding of the edges instead of rounding the entire surface of a stone the way a rotating tumbler will. If you want to round the stones better you must use a rotating tumbler. Another reason your stones are taking so long to get rounder edges is that you should have started with a 60/90 grit or 80 grit, and once all the rough edges have been taken off, then you go to the 220 grit next, then a 400, then a 600, then to prepolish, then to polish stages. One of the most important considerations to keep in mind is the amount of water and grit you should use. In most vibrating tumblers you start with about one half to one tablespoon of grit and just a few spritz's of water from a spray bottle. Just a little to much or too little of either water or grit will dramatically slow down the tumbling action. If you have too much water, the grit will not be carried as well between the rocks. It takes a little experimenting to get it just right. Once you have a little experience, you can tell if the mix is right just by the sound it makes. You don't need to rinse the rocks off unless the tumbling action slows, and even then you can sometimes add just a few drops of water and the tumbling action will be restored. Once you get too much mud in the mix, no amount of water will increase the tumbling action, in fact it may even stop it. The mud that the tumbling creates helps distribute the grit throughout the entire load of rocks, so don't rinse it out until you have to. One important thing to remember, don't rinse the rocks in your sink or any other drain in your house. It can and will clog your drain like concrete. I used to rinse the rocks in a series of 5 gallon buckets that had fresh water in each, and then I'd pour off the water once it had settled out. Now I have a screen that I've built over a large sink that drains directly into a hole I have dug in my back yard and that hole in turn drains off into a ditch. Once the hole fills up with the mud/grit mixture, I cover it with a little dirt and move everything over to a fresh hole I have dug. If you live in town, you probably don't have this option, but I live out in the country and my property is surrounded by sugar cane fields, so I don't have any complaints from my neighbors, and the farmer says the minerals certainly don't hurt the cane. If you live in town, the bucket method will probably work best for you and once the bucket gets full of mud, just wait until it dries and throw it out with the trash. So don't get discouraged. You'll get the hang of it pretty soon and once you do you'll love the results. But remember that to get the well rounded look, you must use a rotating tumbler for at least the first rough grind, and then if you want to finish quicker, you can use the vibrating tumbler.