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Post by knave on Jun 28, 2020 9:14:59 GMT -5
I can see what you did there. Well I do glass at 80 rpm and use SiC 10(using SiC 10 mainly for the time release effect) in the 6 inch barrels. Never came close to shaping it so fast without a single bruise. Lots of high speed rubbing cycles with out the risk of fall impacts in larger diameter barrels. The need to use smalls for padding is virtually eliminated. Roll nothing but target tumbles in the limited barrel space. Shapes a big rock surrounded 100% by smaller 1 inch rocks incredibly fast. The speed may not go over well with product liability issues on a mass produced product. And the increased noise. Home builders should consider the high speed/small diameter approach. So fascinating. It’s interesting to me that the sic breaks down at all with the glass being softer. The truth is revolutionary. 80 revolutionaries to be exact.
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entropy
having dreams about rocks
Member since June 2020
Posts: 71
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Post by entropy on Jun 28, 2020 11:48:08 GMT -5
Question: for the 6" PVC tumblers - after using coarse grit, the inside of the cylinder gets a somewhat rough texture. This increases friction, helping the rocks to tumble (in lieu of slipping). Is there a cleanout issue here? Specifically - does coarse grit tend to stick to the PVC causing scratches in the polishing stages?
I imagine a simple solution would be to make multiple PVC barrels, and never switch grit size across barrels. But that brings up a second question - if only the coarse grit barrel roughens (and assuming the increased friction is desirable) - does polishing performance suffer if the barrel is smooth (never roughened up)?
Tangent question - I've converted two of my metal lathes over to VFD, and I absolutely love it. It's seems like a VFD would be a no-brainier modification/addition for a custom tumbler chassis - aka being able to fine-tune adjust the barrel speed with the turn of a knob. Has anyone here done this? (installed VFD onto a tumbler?)
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entropy
having dreams about rocks
Member since June 2020
Posts: 71
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Post by entropy on Jun 28, 2020 12:24:44 GMT -5
Jamesp, What is SIC 10? Is it Silicone Carbide #10 grit? What is the time-release effect? Is it the grit progressively becoming smaller during use? Which type of 6" barrel where you referring to - for your recommendation to home builders? (PVC, Steel, Rubber, etc?) Conceptual question: one can make a 6" PVC tumbler barrel at 8" long, and one at 60" long, and all the way between. Is there a point of diminishing returns (aside from being to heavy to pickup by hand)? Have you found an ideal length? What is the rule-of-thumb for loading a 6" PVC tumbler barrel? Specifically, when the cylinder is operating, and the rock is evenly distributed down the length of the barrel - how high should the level be in the pipe? (40% up from the bottom, 50% up, 60%, or ). What is the appropriate water level. Is it just enough to cover the rocks? I imagine a much easier way to gauge the target fill-level (which would be applicable to all potential barrel lengths) would be to have the cylinder resting vertical (as it's being loaded) - then it would simply be targeting a ratio of filled space vs empty space. Is this how it's done?
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Post by knave on Jun 28, 2020 12:25:51 GMT -5
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entropy
having dreams about rocks
Member since June 2020
Posts: 71
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Post by entropy on Jun 28, 2020 13:47:31 GMT -5
Thanks for the link knave. The thread(s) answered most of my questions - however;
Quick question (all) - for rough cutting (stage 1) with coarse silicone carbide grit - assuming 6" pipe turning relatively fast (60 to 90 rpm) - what is the life expectancy differences between 6" SCH 40 PVC, and 6" HDPE?
It seems PVC is preferred for the polishing stages. Is that because the coarse silicone carbide grit at elevated speed is a no-no for PVC? Is the difference a function of cost?
Another question - some of the HDPE barrels shown in photographs & videos are well made. They appear to be seamless - rounded ends, with tapered fill-end - almost as if they were cast into this shape. Were they cast? Or are the ends attached to straight pipe sections with HDPE caps/fitting, thermally welded? I have a source for straight sections of HDPE pipe in town (6" and 8") - dressing the ends however. . . .
Tangent topic - VFDs do squeal a bit. Some have a pronounced high frequency whine during operation. Some brands are worse than others. I suppose this noise would be an irritant - if the VFD is within constant earshot. Most of the time the machine being powered is much louder than the VFD noise. It is an odd noise - if you've never heard it before.
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Post by knave on Jun 28, 2020 14:18:14 GMT -5
Thanks for the link knave. The thread(s) answered most of my questions - however; Quick question (all) - for rough cutting (stage 1) with coarse silicone carbide grit - assuming 6" pipe turning relatively fast (60 to 90 rpm) - what is the life expectancy differences between 6" SCH 40 PVC, and 6" HDPE? It seems PVC is preferred for the polishing stages. Is that because the coarse silicone carbide grit at elevated speed is a no-no for PVC? Is the difference a function of cost? Another question - some of the HDPE barrels shown in photographs & videos are well made. They appear to be seamless - rounded ends, with tapered fill-end - almost as if they were cast into this shape. Were they cast? Or are the ends attached to straight pipe sections with HDPE caps/fitting, thermally welded? I have a source for straight sections of HDPE pipe in town (6" and 8") - dressing the ends however. . . . Tangent topic - VFDs do squeal a bit. Some have a pronounced high frequency whine during operation. Some brands are worse than others. I suppose this noise would be an irritant - if the VFD is within constant earshot. Most of the time the machine being powered is much louder than the VFD noise. It is an odd noise - if you've never heard it before. Sch 40 PVC lasts 1-2 years from what I hear. HDPE lifespan is unknown and is much longer. What you saw was an endcap and a reducer, butt fusion welded (on a frying pan)
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EricD
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Post by EricD on Jun 28, 2020 14:18:51 GMT -5
As far as I know there is little to no wear on HDPE from grit. I think Jim said his well-thought-out and constructed PVC barrel lasted 2 years? I'll try to find the thread
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EricD
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Post by EricD on Jun 28, 2020 14:20:36 GMT -5
There's Jim's PVC barrel that lasted 4 years
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Post by knave on Jun 28, 2020 14:21:54 GMT -5
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entropy
having dreams about rocks
Member since June 2020
Posts: 71
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Post by entropy on Jun 28, 2020 16:45:00 GMT -5
Jamesp, the above picture you posted on the thread Eric.D linked. Did you ever build this? I was wondering about the welding process. Specifically - the entire surface-area of the cap would rest on the hotplate, whereas only the outer perimeter area would actually be joined. Is this a problem? i.e. is heating the whole surface for welding, but only joining the pipe-area to the surface - is that bad for the exposed surface that's not being joined? I was searching the HDPE sheet suppliers. Some 1" thick sheets are readily available, and inexpensive. For the end-cap - if 1" thick sheet-material were used, would it be desirable to machine a 1/4" deep countersink into the non-joined center area of the cap? It would ensure only the surfaces being welded contact the hotplate. Same could be done for the 6"x 4" transition piece. Or am I over thinking this. . . . ?
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Post by pauls on Jun 28, 2020 16:45:08 GMT -5
Pauls, what size propane tanks do you use (aka convert) for rock tumbling? (in US gallons, or liters - not sure what they use down there). I guess a better question would be - what's the OD (inches) of the cylinder, and how fast do you turn it (RPM)? Do you put any ribbing on the inside of the tank to encourage tumbling, or does it retain a smooth steel surface throughout? For a standard 5 gallon US propane tank, I was thinking one could weld a piece of 4" NPS Schedule 40 steel pipe onto the cylinder's end (prepping/cutting the valve-end out with a 4.5" hole) - this way a 4" rubber cap can be used to seal the tank (similar to how some PVC tumblers are sealed). Old propane tanks can be had for next to nothing - literally for nothing when they're discarded for recycling. This seems like a very inexpensive alternative to purchasing name-brand tumbler barrels. The biggest potential downside would be noise. Do non-rubber lined propane tank tumblers rattle loudly during operation? My biggest is about 14 inches Dia by about the same long, I cut the stand thing off the bottom, for no good reason, and cut the valve end out about a 10 inch circle, welded 3 bolts, and for the lid a rubber gasket from a bit of conveyer belt rubber and a circle of concrete form plywood. It doesn't need stirrers or anything inside. You are right it is fairly noisy. I have a smaller one that I used one long bolt down the centre. I have it turning fairly fast, because I was looking to speed the process up a bit, it tumbles just as well slower though just takes a bit longer to process the rocks.
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EricD
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Post by EricD on Jun 28, 2020 16:52:53 GMT -5
Jamesp, the above picture you posted on the thread Eric.D linked. Did you ever build this? I was wondering about the welding process. Specifically - the entire surface-area of the cap would rest on the hotplate, whereas only the outer perimeter area would actually be joined. Is this a problem? i.e. is heating the whole surface for welding, but only joining the pipe-area to the surface - is that bad for the exposed surface that's not being joined? I was searching the HDPE sheet suppliers. Some 1" thick sheets are readily available, and inexpensive. For the end-cap - if 1" thick sheet-material were used, would it be desirable to machine a 1/4" deep countersink into the non-joined center area of the cap? It would ensure only the surfaces being welded contact the hotplate. Same could be done for the 6"x 4" transition piece. Or am I over thinking this. . . . ?
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entropy
having dreams about rocks
Member since June 2020
Posts: 71
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Post by entropy on Jun 28, 2020 19:08:21 GMT -5
Interesting - the recommendation was to use a steel/iron ring - to transfer heat to the weld location only - in lieu of heating the entire surface. Seems more cost-effective than adding additional machining operations into the mix. Is a Teflon coating on the heating source a requirement when welding HDPE? Do things become a sticky mess if the heating plate/source is not Teflon coated?
The other concern was deforming/bending the reducer bushing - if not properly supported during assembly.
The thread is over two years old. Where the barrels successfully built?
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EricD
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Post by EricD on Jun 28, 2020 19:34:17 GMT -5
Interesting - the recommendation was to use a steel/iron ring - to transfer heat to the weld location only - in lieu of heating the entire surface. Seems more cost-effective than adding additional machining operations into the mix. Is a Teflon coating on the heating source a requirement when welding HDPE? Do things become a sticky mess if the heating plate/source is not Teflon coated? The other concern was deforming/bending the reducer bushing - if not properly supported during assembly. The thread is over two years old. Where the barrels successfully built? jamesp did you ever complete these? I would assume when melting plastic a non-stick surface would be advisable
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Post by nowyo on Jun 28, 2020 19:53:52 GMT -5
Blasts from the past. Yeah, I made a propane tank tumbler, standard 5 gallon tank. Cut a hole in the top, welded on about 2.5 inches of inch Sched 40 pipe, used rubber cap. Worked fine, but it was loud. At our place in Wyoming it wasn't a problem but here in Nevada we have actual neighbors, most of the doing shift work. The original barrel lasted almost two years before it started wearing through running nothing but 36 grit. Made another barrel, and still have it. Really about as cheap and easy a way to make barrels as there is. On the original I welded two pieces of 3/8 rod inside at 180 degrees for kickers, on the second barrel I left those out. No difference in performance, wouldn't bother with them. Sure could get a bunch of rocks through coarse to keep things moving along. Russ You mentioned that you used the propane tank tumbler to move rocks through the coarse stage. Did you use it do the following stages, or after coarse move the rocks to a different, maybe more conventional smaller tumbler? Henry Only used the propane tank tumbler for coarse grit. My process at that time was coarse in the big tumbler, 120/220 in the QT-6, prepolish and polish in the 45C. That kept things moving along real nice.
I also built a couple of 6" PVC barrels which worked real well. Still have them, need to modify things a little to fit the current space I have.
Russ
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entropy
having dreams about rocks
Member since June 2020
Posts: 71
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Post by entropy on Jun 28, 2020 20:54:44 GMT -5
I found a source for 7" diameter solid HDPE round bar. It isn't cheap, costing about $4.73 per inch-length. Nonetheless, a 2" long section could be machined into a reducer (i.e. 6" NPS pipe-end on one side, 4" NPS pipe-end on the other) which would require just one "pipe" weld - on the reducer end anyway. This solution doesn't seem feasible for mass-production (lots of machining, and lots of waste). There's a pretty hefty minimum order also $$$
Maybe another idea would be to fabricate some heated dies - to neck-down one end of the 6" pipe - to accept the 4" cap (similar to how riffle cartridges are necked down). This would be the ticket - no welding - just taking advantage of the thermo-formability of the HDPE. A separate set of heated dies could also be constructed to form the round pucks into proper caps - facilitating traditional pipe welds (just one weld per barrel).
It would be super-awesome if one set of dies could neck-down one end of the pipe from 6" to 4" (to accept the cap), and another set of dies could could round-off & seal the other end - eliminating all welding, and all machining. This would be ticket for ultra-low-cost mass-production of HDPE tumbler barrels. . . .
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Post by knave on Jun 28, 2020 21:10:00 GMT -5
May i ask. What is your avatar? Looks like a valve stem in the center?
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Post by rockpickerforever on Jun 28, 2020 22:18:57 GMT -5
May i ask. What is your avatar? Looks like a valve stem in the center? To me, it looks like a seven cylinder radial engine. You know, like on old planes like the Spirit of St Louis?
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entropy
having dreams about rocks
Member since June 2020
Posts: 71
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Post by entropy on Jun 28, 2020 22:40:36 GMT -5
It's a Continental W-670 engine (668 cubic inches) from WWII. It has a 12-volt starter, dual-magneto ignition, and the crankshaft has the tank-spline - which means the engine was pulled from either an amphibious landing craft, or a Sherman Tank. It still has the US Army property tag on it. It weighs about 500 pounds.
The wife and I are going to restore this engine and mount it on our living room wall as artwork. It supposedly runs, however I've never fired it up.
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pizzano
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Post by pizzano on Jun 29, 2020 0:07:45 GMT -5
May i ask. What is your avatar? Looks like a valve stem in the center? To me, it looks like a seven cylinder radial engine. You know, like on old planes like the Spirit of St Louis? You'd be very accurate........The R-670 or factory designation W670, was a common engine used in PT-17 Stearman training aircraft.....I have/had a few RC aircraft with that replica engine (non-operational)..........however, there have been scaled down mechanical versions installed into scale RC models, that actually run and fly......and yes, as the OP stated, it was used for a short period of time in light armored WWII vehicles.........cooling, fuel distribution/economy, ignition and maintenance issues made for a terrible land craft engine, it didn't like dirt or mud much.....!
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