entropy
having dreams about rocks
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Post by entropy on Jun 27, 2020 17:53:34 GMT -5
I'm tinkering with the idea of building a large rock tumbler using steel only. Is there any disadvantage that I'm missing? Is it possible to obtain a quality finish through all four stages of the process - or will the steel be too traumatic on the rock? I understand that a steel tumbler (without rubber liner) will be quite loud. Fortunately no one is within earshot of my shop (I live out in the woods). What is the best tumbler shape for a larger steel design? (round or hexagon)? My options are to use a large diameter steel pipe, or to fabricate a hexagon barrel using plate. My goal is to be able to tumble larger rocks - not necessarily tumbling larger volumes of smaller rock.
Please advise?
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EricD
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Post by EricD on Jun 27, 2020 18:09:49 GMT -5
I've always had thoughts about trying that. I would go with a round barrel to minimize unnecessary impacts.
I envy you! Living out in the woods! Don't forget your own sanity though, if there's any left!
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Post by HankRocks on Jun 27, 2020 18:18:12 GMT -5
If you are planning on a Rotary Tumbler, then the steel is probably going to be too "traumatic" on the rocks, especially in the Polish stage. You will need a lot of Pea Gravel and slurry to make this work.
Your other issue will be large rocks tend to fight and bruise each other pretty badly. If you put several large in a big barrel it's going to be a real slugfest. The physics of several moving masses works against you.
What size barrel are you thinking about?
Henry
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EricD
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Post by EricD on Jun 27, 2020 18:22:31 GMT -5
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entropy
having dreams about rocks
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Post by entropy on Jun 27, 2020 18:32:29 GMT -5
I have a 30" diameter section of pipe (3/4" wall) - about 5 feet long. It is rolled (spiral edge-wound - like a paper tube) and seam-welded. It is medium strength steel (51 ksi yield). Aside from the slight bulge of the weld-seam, the inside is completely smooth.
I'm worried that without some extra grip (strips/shapes welded inside the barrel) that rocks will not tumble - but rather that the barrel will simply slip around the rocks - without much tumbling going on.
I can get crushed basalt rock super cheap. I think it would make great fill. Or would round rock be better fill? So many questions. . . . . .
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Post by HankRocks on Jun 27, 2020 18:37:01 GMT -5
You need to also consider the clean outs, they could be a back injury waiting to happen. Some sort of system to help with cleanouts might be warranted.
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EricD
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Post by EricD on Jun 27, 2020 18:39:44 GMT -5
I have a 30" diameter section of pipe (3/4" wall) - about 5 feet long. It is rolled (spiral edge-wound - like a paper tube) and seam-welded. It is medium strength steel (51 ksi yield). Aside from the slight bulge of the weld-seam, the inside is completely smooth. I'm worried that without some extra grip (strips/shapes welded inside the barrel) that rocks will not tumble - but rather that the barrel will simply slip around the rocks - without much tumbling going on. I can get crushed basalt rock super cheap. I think it would make great fill. Or would round rock be better fill? So many questions. . . . . . jamesp makes round barrels out of HDPE and has done some pretty extensive testing with different RPMs and slurries. You can do some searching around the forum through his posts, or wait for him to see that I tagged him.
I don't think the shape of the filler rock will be a problem. The large stone (the single one you will be rolling at any given time) will beat the living daylights out of anything else in there
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jamesp
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Post by jamesp on Jun 27, 2020 18:58:30 GMT -5
Lots of old timers built out of steel.
My vibe is a home made steel hopper with no rubber or poly coating and it is used to tumble polish delicate glass.
Never have any bruises or impacts on the glass and always a fine polish.
If you watch a rotary rotating at design speed of a typical rotary rock tumbler there is not a lot of impact against the walls of the tumbler barrel.
At 30 inches diameter you'd need to turn about 8" dia/30" dia X 30rpm = 8 rpm. Based on an 8 inch barrel on a Lortone turning about 30 rpm. Such a slow speed would need a double reduction belt system or more likely a gear box. Probably 5hp motor, $$$ electricity.
Delving into new territory. Who knows what may really happen. Don't assume you can fill it up with 3 to 6 inch rocks without a lot of protective smalls like perhaps the basalt. Most basalt makes a lot of mud though. Harder quartz might be the way to go.
I concur with Henry regarding clean outs. The coarse grit would be short lived in such a large diameter.
The use of a crane would be about mandatory.
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entropy
having dreams about rocks
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Post by entropy on Jun 27, 2020 19:00:23 GMT -5
This gets back to the root of the question. If the barrel is 30" diameter x 5-feet long, my assumption is that I could put 15 to 20 rocks, sized between 5" and 8". Then several cubic feet of 3/4" clean crushed basalt rock, a bag of silicone carbide grit, and water.
The million dollar question - Am I more than likely to damage the large rock? Or with the proper amount of fillers & water, and with proper speed control - is it possible to tumble-polish large rocks? (aka to scale-up the traditional rock tumbler)?
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entropy
having dreams about rocks
Member since June 2020
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Post by entropy on Jun 27, 2020 19:09:17 GMT -5
Conceptual question about grit being short-lived -
Assume I put in a 50 pound sack of #16 grit black silicone carbide. By turning a large volume (of large rocks), the grit will consumed long before a week of tumbling is up. Would I simply add another bag in a few days? Does the pulverized grit need to be removed first?
I'm assuming that my filler rock will also consume the grit. Are plastic filler beads ineffective for large-size tumblers?
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EricD
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Post by EricD on Jun 27, 2020 19:20:29 GMT -5
Conceptual question about grit being short-lived - Assume I put in a 50 pound sack of #16 grit black silicone carbide. By turning a large volume (of large rocks), the grit will consumed long before a week of tumbling is up. Would I simply add another bag in a few days? Does the pulverized grit need to be removed first? I'm assuming that my filler rock will also consume the grit. Are plastic filler beads ineffective for large-size tumblers? You would need to clean it out, because of the mud the rocks and worn grit would produce. If not cleaned out you would end up with an overflowing barrel of sludge. Cleanouts would be a b***h. That's why I don't own a Diamond Pacific 65T already
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Post by HankRocks on Jun 27, 2020 19:21:14 GMT -5
You need to calculate the volume to determine how much grit. With the larger diameter you will have lots of grinding, therefore lots of slurry being produced. You might have to drain some of the slurry, before the next re-charge of SiC, too much slurry and you kill any motion in the barrel.
Lots of issues to consider, but a very interesting idea. You should get lots of advice out here. I will follow the discussionto see where it goes.
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EricD
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Post by EricD on Jun 27, 2020 19:24:11 GMT -5
Thanks Jim for the quick reply and yes, I concur with Henry and Jim that a crane or hoist of some sort would be a real need. Forklift maybe
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EricD
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Post by EricD on Jun 27, 2020 19:28:33 GMT -5
This gets back to the root of the question. If the barrel is 30" diameter x 5-feet long, my assumption is that I could put 15 to 20 rocks, sized between 5" and 8". Then several cubic feet of 3/4" clean crushed basalt rock, a bag of silicone carbide grit, and water. The million dollar question - Am I more than likely to damage the large rock? Or with the proper amount of fillers & water, and with proper speed control - is it possible to tumble-polish large rocks? (aka to scale-up the traditional rock tumbler)? We need to address this 15-20 5" to 8" large rocks problem. They will beat eachother to death in there. You are only allowed one large rock! |
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entropy
having dreams about rocks
Member since June 2020
Posts: 71
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Post by entropy on Jun 27, 2020 19:35:44 GMT -5
Where is the best place for cleanouts?
Assuming I cap the ends of the pipe with some 1" plate, weld some 3" shaft-ends onto the caps (to be supported by some large 3" pillow-block bearings) - my options for cleanout holes are on the end-plates, or on the cylinder body/wall.
I don't like the idea of compromising the cylinder wall with access cuts. It's going to interfere with the tumbling. Putting large access cuts into both end-caps seems like the best idea. A few capscrews to hold the access plates on (with heavy rubber gasket). I could open the covers while orientated at the 12 o-clock position, then rotate the barrel slowly to the drain position (6 o-clock) - letting the water/sludge out in a somewhat controlled fashion. I could reach in a good 1.5 feet with my arm, on both sides. The contents that are out-of-reach I could push to either end with a push-stick. The piece of pipe I'm considering using weighs 1200 pounds. The weight will only go up after I weld plate onto the ends, and attach rotary shafts. I don't want to remove (or otherwise lift) the barrel from the chassis. I also don't want rocks dropping on my feet.
I'm assuming a simple NPT drain plug (for dewatering) would be ineffective - the sludge & fines would probably plug the opening.
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EricD
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Post by EricD on Jun 27, 2020 19:40:17 GMT -5
Where is the best place for cleanouts? Assuming I cap the ends of the pipe with some 1" plate, weld some 3" shaft-ends onto the caps (to be supported by some large 3" pillow-block bearings) - my options for cleanout holes are on the end-plates, or on the cylinder body/wall. I don't like the idea of compromising the cylinder wall with access cuts. It's going to interfere with the tumbling. Putting large access cuts into both end-caps seems like the best idea. A few capscrews to hold the access plates on (with heavy rubber gasket). I could open the covers while orientated at the 12 o-clock position, then rotate the barrel slowly to the drain position (6 o-clock) - letting the water/sludge out in a somewhat controlled fashion. I could reach in a good 1.5 feet with my arm, on both sides. The contents that are out-of-reach I could push to either end with a push-stick. The piece of pipe I'm considering using weighs 1200 pounds. The weight will only go up after I weld plate onto the ends, and attach rotary shafts. I don't want to remove (or otherwise lift) the barrel from the chassis. I also don't want rocks dropping on my feet. I'm assuming a simple NPT drain plug (for dewatering) would be ineffective - the sludge & fines would probably plug the opening. The ends would be best, yes. I'm going to stop giving any advice after seeing the tube weighs 1200# Be safe and have fun
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entropy
having dreams about rocks
Member since June 2020
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Post by entropy on Jun 27, 2020 19:44:59 GMT -5
At which point is a rock considered large?
So it is not possible to tumble a batch of large rocks, within a large tumbler?
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entropy
having dreams about rocks
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Post by entropy on Jun 27, 2020 20:01:18 GMT -5
There's high confidence that one large rock rolling around a steel drum, cushioned by lots of smaller rocks & slurry will prevent bruising upon the large rock.
Are we positive that several large rocks rolling around within a steel drum, cushioned by appreciable amounts of smaller rocks & slurry will NOT prevent bruising? If the answer is no, then the project is basically a no-go.
Eric.D - please don't be intimidated by large parts. I've got a forklift, and a 16,000 pound gantry crane out in the shop.
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EricD
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Post by EricD on Jun 27, 2020 20:11:57 GMT -5
There's high confidence that one large rock rolling around a steel drum, cushioned by lots of smaller rocks & slurry will prevent bruising upon the large rock. Are we positive that several large rocks rolling around within a steel drum, cushioned by appreciable amounts of smaller rocks & slurry will NOT prevent bruising? If the answer is no, then the project is basically a no-go. Eric.D - please don't be intimidated by large parts. I've got a forklift, and a 16,000 pound gantry crane out in the shop. No worries, I work with large amounts of steel as well. My confidence in others ability to safely do so is lacking. If you have experience rolling rocks in a tumbler, you know that the more large rocks you roll in it, the more bruising you get. If you run one huge rock with gravel, nothing but the gravel suffers
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Post by knave on Jun 27, 2020 20:16:21 GMT -5
Crushed basalt will quickly turn into mud. Dewatering could be done with 1.5 or larger NPT. Maybe 4” would be best.
Assuming it’s for rough only, you could have the barrel on an angle and let the rocks come to you, wash out with a garden hose...
Just musing.
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