docharber
has rocks in the head
Member since October 2008
Posts: 716
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Post by docharber on Jan 11, 2009 14:12:55 GMT -5
I've read several posts about ceramic pellets for filler. It sounds like a great idea for hard to polish stones but I have noticed it ain't cheap. how long do the pelletss last?
Mark H.
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1Mark
noticing nice landscape pebbles
Member since November 2004
Posts: 91
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Post by 1Mark on Jan 11, 2009 14:32:31 GMT -5
Use 'em in the rough stages of either a vibe or a rotary and they'll be worn away pretty quickly. I use the larger angle-cut cylinders for filler in the 500 grit or finer stages in my vibe, and I sometimes use the 4mm spheres when polishing softer (5-6 mohs) stones. They seem to dampen the action of my Lot-O a bit due to the extra mass (you can cram more weight/mass into the barrel by filling out a load with these small spheres). I recently measured a random sampling of spheres that had been used in 2 loads in 500, 1000, tripoli pre-polish, and final polish stages and couldn't detect any shrinkage with my digital caliper.
Mark
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ejs
spending too much on rocks
Member since July 2008
Posts: 478
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Post by ejs on Jan 11, 2009 15:37:49 GMT -5
I use medium-sized slant-cut ceramic cylinders. I use them mostly in the 60/90 SC rough stage. I would guess that they last 8 rounds in rough before being ground completely down.
You could always use scrap rock or smashed up found rock as a cheaper filler.
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darrad
fully equipped rock polisher
Member since September 2006
Posts: 1,636
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Post by darrad on Jan 11, 2009 15:51:16 GMT -5
I use pellets in my rotarys. They seem to last next to forever which I have never been able to figure out since the're plastic.
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docharber
has rocks in the head
Member since October 2008
Posts: 716
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Post by docharber on Jan 12, 2009 20:31:36 GMT -5
Thanks, guys. I think just saving my little scraps as I've been doind is the best bet, but I thought maybe for some harder to polish material like sodalite (a real pain for me) or blue apatite, etc imight help. I've tried plastic pellets without success. I found a piece of mahogany obsidian I had left in the polish stage somehow with jaspers and agates and it came closer to polished than anything i'Ve achieved so far with this stuff. I've uused Ao and CO polishes with and wiwthout pellets and no pellets gives a better shine but is hard on the rocks. i thought the ceramic anfle cut stuff or shot would be helpful. It sounds pricey though for this purpose (or any other!). I'll try using little bits of polished agates, etc. instyead- they're sheap and plentiful. I just haven't understood whuy people use the ceramic media at such a dear price.
Mark H.
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ejs
spending too much on rocks
Member since July 2008
Posts: 478
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Post by ejs on Jan 13, 2009 10:09:12 GMT -5
I can see your point about the ceramic being a waste of money. After all, it gets ground down to nothing. But then again, so does the grit! I purchased a 5 lb. bag of pellets for $17.50 and have been using it for a long time (with 5 barrels dedicated to rough). I recharged a barrel of carnelian agate in coarse yesterday. It was going into its 8th round, and I noticed that the ceramic was just about worn away (very thin, some pieces had shattered). I don't use a lot, just a small handful (perhaps 20-25 pieces) in a 3 or 6 lbs. barrel to encourage good grinding/shaping.
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docharber
has rocks in the head
Member since October 2008
Posts: 716
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Post by docharber on Jan 17, 2009 0:18:58 GMT -5
I was under the imopression it cost a lot more and you needed a lot more. I may give it a try and see how things work out. I appreciate the input.
Mark H.
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Post by johnjsgems on Jan 17, 2009 0:56:26 GMT -5
A useful formula is to fill drum with rock to 2/3 full then add ceramic media to bring it up to 3/4 full.
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Post by catmandewe on Jan 17, 2009 1:23:20 GMT -5
You could also use broken auto glass, it will do the same thing as the media, and most body shops will give you as much as you want.
Tony
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earthdog
Cave Dweller 
Don't eat yellow snow
Member since June 2006
Posts: 2,731
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Post by earthdog on Jan 17, 2009 12:03:38 GMT -5
What is that? Never heard of it before... ;D
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docharber
has rocks in the head
Member since October 2008
Posts: 716
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Post by docharber on Jan 19, 2009 14:21:19 GMT -5
They're ceramic bits in specific shaopes used as filler and grit carriers. I asked because I was wondering wht the advantages of this stuff might be compared to other really sheap substitutes. I was under the impression initially that a lot more was needed and that uit cost way more than it does. Any lapidary supply carries the stuff and you can find pictures online. .
Mark H.
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Post by Hard Rock Cafe on Jan 20, 2009 8:47:03 GMT -5
Up until recently, I was a firm believer. I used to use ceramics in my vibe, on the advice of Val from Minnesota Lapidary Supply. I used the large angled cylinders and the smaller pellets. The idea is that you need a load with a wide range of sizes, especially smaller rocks to get into the nooks and crannies.
For a long time, I didn't see much degradation and I was getting good results. However, I've mostly been tumbling Lakers and for several rough grinds I noticed that the ceramics were getting smaller, I had a lot of mud, and the Lakers were not grinding much at all. Obvious conclusion: the ceramics were softer than the Lakers.
My current hypothesis is that the surface of the ceramics is harder than the interior. Once the surface is worn away, the interior erodes more quickly. It's just a guess.
At any rate, I didn't use them on this round; the Lakers ground nicely and they're polishing.
Hope that helps.
Chuck
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chassroc
Cave Dweller
Rocks are abundant when you have rocktumblinghobby pals
Member since January 2005
Posts: 3,586
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Post by chassroc on Jan 20, 2009 11:30:33 GMT -5
You should never, ever, ever use ceramic pellets or anything that costs money in the coarse stage of grinding. You do not need cushioning, you want as violent action as you can get. You want to maximize breakage early rather than later.
If you need filler because you do not have enough rocks to fill the barrel, use anything you can find, river rocks, pebbles, driveway rocks, etc. They will all do the job and do not cost anything.
csroc
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docharber
has rocks in the head
Member since October 2008
Posts: 716
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Post by docharber on Jan 20, 2009 13:21:55 GMT -5
I had been under the impression most folks use them for polishing. The satiny surface will be about right to hold particles of fine grits or polishes. Ceramnics are generally microcystalline silica containing materials, though softer silicates like sodium or potassium or calcium silicates that are in very fine particles held together with a vitrified silica (glassy) binder. The binder gives way first. I don't think there is much difference in the hardness from inside to outside, but as the pellets get smaller, their dimensions will appear yto shrink faster (proportionately). It is possible, though, that the surface is more vitrified/fused than the interior and maybe moire oxidized/reduced by the atmosphere in the kiln, and therefore harder or more homogenously hard. Interesting idea.
I don't know what sort of ceramic these are made of- "Ceramic "materials can be made of metallic oxides like microcrystalline CZ, for instance, used to make knife blades. I think this stuff is more of a stoneware material, though. They could also be porcelain. In any case, 6.5 is as hard tas they would get, and probably a lot less.
Mark H.
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Post by johnjsgems on Jan 20, 2009 20:49:20 GMT -5
csroc, other than filling a load, ceramics serve as tiny rocks in the load to speed up the process so are useful in coarse grind where no small stuff is available. You are right that gravel (pea size or smaller) would also work.
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chassroc
Cave Dweller
Rocks are abundant when you have rocktumblinghobby pals
Member since January 2005
Posts: 3,586
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Post by chassroc on Jan 21, 2009 10:03:54 GMT -5
John ...Congradulations on reaching a landmark post; you are correct about the ceramics
csroc
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Post by Hard Rock Cafe on Jan 21, 2009 19:38:30 GMT -5
I should also clarify: I do the bulk of my coarse grinding in a rotary and finish them off in the vibe. For most rocks I wouldn't need to do a coarse stage in the vibe, but the Lakers often have little imperfections that I can fix more quickly in the vibe once they are shaped.
I have a number of large-ish Lakers and sometimes need smaller filler material. Val's recommendation was 1/3 tiny (like pellets), 1/3 medium (like the angled cylinders), and 1/3 larger (up to 1.5" or so), with maybe 3 goose egg size stones in my UltraVibe 18.
Chuck
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rockdewd
has rocks in the head
Member since October 2007
Posts: 605
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Post by rockdewd on Jan 22, 2009 11:05:57 GMT -5
The rule around my shop is that anything large enough not to fall through the colander gets tumbled. I keep small bits and pieces in my rotaries for what I call "slave" pebbles to distribute the grit. Sometimes I get some pretty interesting stones for cabs that way. They grind away until they are small enough to fall through the colander when I'm washing out the barrels.
I use my barrels for rough stage (60/90) tumbling only. I do the successive stages and polish in vibe tumblers.
For vibe tumbling I use a combination of ceramic cylinders, triangles, glass marbles, broken pyrex pot lids, broken tempered glass, and broken regular glass. Caution: I tumble the broken glass first in a rotary tumbler with 60/90 to remove the sharp edges. I avoid vibe tumbling the small "slave" pebbles because I have small cabs in the vibe tumblers and it makes it a pain in the a$$ to sort them out. If I have more "slave" pebbles than I need I run them through the vibes and finish them. I the give or sell them to teachers for art projects.
Rick
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