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Rotary tumbler question

I’m wondering about rotary tumbler options for burnishing silver. I have a Lortone 3a base, which will run either a 3 lb or a 1.5 lb round drum. I’d like to be able to burnish a few rings, small pendants and chains in a run…I don’t make a lot of stuff at once, being a hobbyist. It seems I’ve read in Judy Hoch’s book that the tumbler should have straight sides, but the Lortone drums are circular. Could I use the Lortone 1.5 drum with 1 lb of stainless shot or the 3 lb drum with 2 lbs of stainless shot for burnishing, or do I need to completely change out to another system. I have looked for a straight sided drum, but don’t find any small rotary tumblers outfitted like this. Any feedback?
Thanks,
royjohn

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I have a Thumler’s Tumbler AR 12. It is fairly small. For even smaller loads I prop it up diagonally \

They seem to be not in business or perhaps temporarily closed. Kinglsey North, Contenti, and perhaps others may have one in stock.

Hope this helps.

Regards,
Neil

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I have the Lortone 3A and run it with 1lb steel shot most days. Does a great job, reasonably quiet and doesn’t get excessively hot (which was a thing a lot of people seemed concerned about, when I was researching before buying). I’m curious what difference the shape of the barrel is supposed to make. I know I’ve seen some from Rio that have hexagonal or octagonal clear plastic barrels, but that seemed to me like it would be a lot louder so I wrote them off my list pretty early.

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Hello Jen,
Thanks for your input…are you running a 1.5 lb barrel on the 3A or a 3 lb barrel?

Thinking about it, if the only added cost is $3 more for the bigger barrel and another $8 for a second pound of SS shot, I guess I’ll just go for the 3 lb barrel. I could run just one ring or ten in that, no?
Thx,
royjohn

While there are advantages to straight sided drum in production, I really think you are going to be fine with the batch size you describe.
Change out your soapy water on a regular basis. This will depend on use, as well as, time spent sitting idle. Fresh, soapy water makes for a brighter finish. Sometimes, if it has sat for a while between runs, I let it tumble for several minutes, then rinse throughly and add new soap and water. Then experiment with cycle time. Start around 12 minutes, observe, then go up or, next time go down. Fifteen minutes is my typical cycle with pre-vibed castings.
Barrel size, at the price you describe, I’d go larger. You can always grow into it. Plus, you may find the larger diameter give a bit more action to the media tumble.
Jeff Deegan

Hey Jeff,
Thanks for your help! If the tumbler sits for very long (and it might, as I work in fits and starts) I’ll drain it and leave the shot out to dry. I appreciate what you’re saying about building for the future, but I have a 3A base and can outfit that for about $70…$45 for the drum and $25 for the 2 lbs of shot. I do have a drum for a 45C (a five pounder), but I don’t have a base for it, so outfitting that way would more than double my costs, which I’d like to avoid for now. Might be able to rig an old photography color drum to run the 45R drum later…-royjohn

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I honestly don’t know which barrel it is- if there’s one considered “standard” that comes with the 3A, that’s the one (purchased direct from Lortone, basic kit). I can measure it later today if that would be helpful. And yeah I think you’re right, it matters what the overall weight in the barrel is but not how much of it is shot versus jewelry (unless you get into ridiculous proportions with jewelry outweighing shot, obviously).

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If you don’t mind, can you explain this a little? I’m really curious about the differences.

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If the inside of the barrel is round and smooth, the shot and jewelry charge will likely slip as the barrel turns rather than “tumble”. The flats molded into the rubber liner of the barrel pick up a small amount of the charge and flips it over on itself. This causes the shot to impinge on the jewelry and burnish it. There is a good discussion of how this works in Judy Hochs book Tumble Finishing for Handmade Jewelry. Kingsley North is a good source for tumblers and tumbling supplies. My SS tumbler is a QT6 Lortone model that works well for small runs. I use it mainly to tumble finish ear wires, smaller earrings and to clean up jewelry that has become a bit shop worn. It holds 5 - 6 pounds of shot. Rinse and change the burnishing solution often. I have three flow through vibratory tumblers to sand and prepolish new larger pieces. Each tumbler has a different type of media in it so that I don’t have to constantly change media and clean the barrel. Regardless of what I do, I always final polish bigger pieces on a wheel. Read Judy’s book, it will put all of this in perspective…Rob

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Sure, tumbler barrel interiors can be either be smooth walled cylinders or square walled [like a box] or multi walled [eg. octagonal]. Each iteration as it revolves tends to “pull” the work and the media “up” the interior lining wall until gravity causes the media mix to slide back on itself. This is the action that results in the media rubbing against the work pieces with the work pieces rolling around and in a quick split second the revolving drum repeats this cycle again and again.
Multiwall barrels do the same, the idea that the multiple interior staight sides make for a bit more agitation to the media and work. Sometimes this can result in visible planish marks on the work [work:media: volume can affect this]. The multi walled tubs I’ve more frequently encountered in larger industrial applications, like plating shops.
Almost all of my work is hand polished with the exception of some small parts and pieces designed with a more deliberate rustic finish. For this I’ve always used the smooth sided barrels and the results have been quite good. As I wrote earlier, experimentation will lead you to suss out the best combo of pre finish, tumble duration, water changes. Remember, even stainless shot will get a little gunked up if left in a wet tube for long periods of time. If so, drain, rinse, add water/soap, then run for 10 min or so to brighten up before you put work in.

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The Lortone 3A comes with a 3lb barrel that fits and fills the opening on the base, so that’s apparently the one that you have. The 33B comes with two 3lb drums, but can also be fitted with three 1.5lb drums and it comes stock this way as the 3-1.5B. The bases for all three of these models take the same diameter of drum, so I assume you can run the 1.5lb drum on any of them. The 1.5lb drum is 2 5/8" tall, the 3 lb drum is 4 3/4" tall, so apparently you could not run two 1.5lb drums on the 3A. -royjohn

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The old black rubber barrels are prone to creating black schmutz. It has to do with the barrel breaking down. Today I recommend the newer nylon or plastic barrels. Most have a cam lock system that is much easier to close and never leaks. The newer barrels all are hexagon shaped so the steel gets picked up and then returns burnishing the jewelry. You can accomplish the same thing by hand with a burnisher, it just takes a lot longer. The special compounds created for burnishing result in a far better shine. Just using soap seems pretty good until you find out how good it can really be. My burnishing runs are about 45 minutes. Anything longer starts to damage the surface of the metal. And for any of you trying to get a copy of my book, I’m deep into a new version and everybody is out of stock. I’ll tell you all here when it is available. Judy Hoch

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Thanks for the explanations on the barrel shape! Makes total sense.

Regarding the black schmutz, open a can of coke and let it sit out overnight, then dump it into your rubber barrel with steel shot and let it run for a half hour. Sounds goofy, totally works! I’ve had my tumbler a couple years, and I’ve done this maybe three times including when I first got it. It really helps. Come to think of it I probably ought to do it again.

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There is dilute phosphoric acid in Coke, this is the same thing that is in naval jelly…it is a rust remover. The black schmutz must be some form of oxide or rust and the phosphoric acid removes it. I’m guessing it is a black form of iron oxide rather than the typical red form we’re all familiar with as rust. But perhaps some other oxide. Yeah, make sure the Coke is flat or your tumbler might explode or bulge and leak. -royjohn

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Yup, exactly! Works great on chrome trim that’s starting to rust too, if you can manage to find a car made from actual metal anymore…

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I have one more rotary tumbler question, which I’ll ask here rather than start a new thread. Assuming I am fabricating silver and hand finishing with sandpaper and buffs, where would I put my burnishing-in-rotary step? It would brighten and harden my pieces, but would I do it after fine sanding (to 400 to 600 grit) of after buffing with tripoli, or after buffing with rouge? -royjohn

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Do a couple test pieces and see which works best with your particular processes and materials. Before I used to do fine sandpaper/radial disks, tumble, then Tripoli and rouge; when I switched to Luxi compounds I found I prefer to use the Luxi black first, then tumble, then use the blue and orange compounds.

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royjohn - if you think of using a manual burnisher, that is where you would use the tumbler burnisher step. After everything. - then set your stones. judy hoch

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I honestly get great burnishing results from a cheap, well-used dual tumbler from Harbor Freight. I initially got some rubber bits in there, but they’ve long since worked themselves out. I’ve got straight-sided here as well and get no better results. Also have a magnetic tumbler and a vibratory with a variety of grits. If I’m polishing to a smooth matte finish before a final polish, I might use one of those. But for burnishing/polishing work, the round-sided rotary works fine for me. I run it for 2 hours on a timer. Any longer, and I wind up having to do a thorough cleaning post as the burnishing compound tends to make a mess (if I’m using dish soap, I don’t have this issue).

The idea that smacking repeatedly against the side of the metal from a straight-sided tumbler is somehow better than rolling against it in a slow compression wave is something I’d have to see legitimate physics data to support. I can’t imagine how. It might be faster, but more effective? Does anyone have any testing data on hardness and metal compression to show that?

Thanks, Neil,
That is helpful info. Well, now I’m clear that I would use this burnishing step last, right before setting stones, if any. So now my question is, why do it at all, if I’m doing all my finishing steps right thru rouge? Is it just used for some hardening, or does it actually contribute to a brighter finish?
Thanks,
royjohn