jamesp
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Post by jamesp on Jun 29, 2020 5:51:43 GMT -5
entropy - This link has photos of my system after may years of testing. Less a modified Vibrasonic vibratory tumbler. 2 speed tumbler that can be altered in speed with ratio changes. 6" and 8" I.D. HDPE barrel builds Aggressive raw metallurgical grade SiC at 45 cents per pound that lasts a long time(time release). www.flickr.com/photos/67205364@N06/sets/72157673297787998I do coarse shaping and pre-vibe finish steps in rotary tumblers. I do finish steps in vibes. I use silicon carbide with a clay slurry thickener for all rotary steps and aluminum oxide with a sugar slurry for all finishing steps in a vibe. Sometimes SiC 500 in the vibe if in a hurry. Yes a PVC or HDPE pipe barrel can be 12 or 96 inches long. HDPE is the only plastic I could find that lasts a long time running abusive large raw SiC at high speeds. Larger diameters require smalls/attention to slurry quality/slow speeds as they are more able to bruise rocks/glass. The HDPE barrel utilizing plate HDPE is a proprietary build. Intent to market some day. Other than that no secrets.
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entropy
having dreams about rocks
Member since June 2020
Posts: 71
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Post by entropy on Jun 29, 2020 10:54:47 GMT -5
Understood - I'll stop asking about your HDPE/plate build.
I am curious about the metallurgical grade SIC. Some of the pieces are quite large. It looks like you are screening/sorting the contents into different grit sizes. Do the very largest sizes get used? Is this what you mean by time-release (aka they take a long time to breakdown into smaller pieces?) Or do you further process the largest chunks into smaller pieces (hammering/crushing) - prior to tumbling?
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jamesp
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Post by jamesp on Jun 29, 2020 11:13:22 GMT -5
Understood - I'll stop asking about your HDPE/plate build. I am curious about the metallurgical grade SIC. Some of the pieces are quite large. It looks like you are screening/sorting the contents into different grit sizes. Do the very largest sizes get used? Is this what you mean by time-release (aka they take a long time to breakdown into smaller pieces?) Or do you further process the largest chunks into smaller pieces (hammering/crushing) - prior to tumbling? The easiest path to an HDPE barrel is buying a reducer and a cap end fitting and sticking them together using teflon fry pans. At higher speeds and using sticky slurry the abrasive breaks down much faster. These bigger chunks of SiC simply take a longer time to break down entropy. Yes the raw SiC is sifted to two sizes, SiC 60 and smaller, Sic 60 and bigger. The raw SiC comes in a 50 pound bag mixed with SiC particles starting at 3/8" and from there smaller to very fine. The last run in step 1 is run with the finer of the two. Often there are big chunks leftover when running the coarse blend. The raw SiC is by far my biggest money saver when tumbling. It could be crushed. I let the tumbler and rocks break it down. Rarely more the a tablespoon of big chunks left over and they are tossed. The big chunks are somewhat tumbled smooth. SiC is like glass. It is brittle and breaks into sharp pieces. That is why it coarse shapes rocks so well.
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jamesp
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Post by jamesp on Jun 29, 2020 13:29:04 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
Eric, Sch 40 PVC barely lasted a year running the raw SiC at high speeds. About the same for factory Lortone caps. Lortone rubber is indestructible. The HDPE sure looks good after about 2 years. It does get a rough abraded surface. Funny, the SDR 11 pipe and fittings is often cheaper than the SDR 17 pipe and fittings. The SDR 11 is freak out thick. I could never see it wear out. Plus it could be drilled and tapped for bolt on connections due to it's thickness. Another bonus with SDR 11, there is a lot more weld surface area to get the weld right in case equal heating was not achieved. The SDR 11 is thicker in the inside direction meaning it is less than 6 inches in I.D. I would probably opt for 8 inch fittings/pipe due to the decreased I.D. if going with SDR 11. There is yet thicker HDPE pipe, like SDR 7 and thicker, crazy. SDR 7 6" pipe is almost 1 inch thick but only 4.6" I.D. SDR 7 8" pipe is almost 1.25 inches thick but only 6" I.D. ! These things are heavy empty.
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EricD
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High in the Mountains
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Post by EricD on Jun 29, 2020 13:49:48 GMT -5
Wowzers, almost a 3" wall for a 20" pipe!
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entropy
having dreams about rocks
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Post by entropy on Jun 29, 2020 15:05:52 GMT -5
If using a 6" cap, and a 6"x 4" reducer (DR-11 wall-thickness "but-weld" fittings) - the inside of the barrel will be 5.421" diametrically. Is this too small? Is the goal to have an actual 6" ID? Using 8" DR-11 reducer & cap should yield a 7.057" ID. The DR-11 and DR-17 pipe fittings are considered regular items (aka lower cost). I anticipate DR-7 and DR-9 fittings to be appreciably more expensive.
Our local blasting supply does not sell metallurgical grade silicone carbide. The sales lady had never heard of it. Very strange - considering these people sell high-volumes of the widest selection of grit known to man. . .
Do you mail-order your metallurgical grade silicone carbide (presumably paying freight) - or do you pick it up at a terminal? At 45 cents per pound, a ton would cost 900 bucks. I could probably sell that purchase to the wife - telling her it's practically a lifetime supply of grit. . . .
Tangent question - does silicone carbide have any special storage requirements? I'm assuming the bags need to be stored out of the rain.
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EricD
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Post by EricD on Jun 29, 2020 16:18:26 GMT -5
I don't think a half inch here or there is anything to worry about, you can always adjust the speed with a VFD or pulley changes.
Metallurgical grade SiC is not an abrasive per-se, it's used in metal alloys.
You would need to pick it up of have it shipped freight.
Only the bags would react to water, you can store it anywhere.
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entropy
having dreams about rocks
Member since June 2020
Posts: 71
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Post by entropy on Jun 29, 2020 20:12:44 GMT -5
Agree, it's not blasting grit. Nonetheless I'm still surprised that a major distributor of silicone carbine, aluminum oxide, ceramic, glass, plastic, and steel-shot, etc - that they've never heard of metallurgical silicone carbide - considering that we've got several steel foundries in our area (casting heavy machine parts) - that would likely use this substance within their arc/blast furnaces. Perhaps it's such a specialty product that consumers purchase directly from the manufacturer?
Tangent question - which site do you guys recommend for web-hosting photographs? I was using Photobucket for many years, however Photobucket has recently become dysfunctional. I don't mind paying a small monthly fee - provided I actually get the service I'm paying for (unlike Photobucket). . . .
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Post by knave on Jun 29, 2020 20:18:16 GMT -5
I can maybe help with the photo question. Some on here use Flickr. Google photos doesn’t play nice with ProBoards. There is integration with Cloudinary for this website, it takes some setup, there’s a stickied tutorial in the new user forum. Cloudinary is free and works good, it’s what I use for this site.
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jamesp
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Post by jamesp on Jun 30, 2020 6:05:01 GMT -5
Silicon carbide is stable like a rock. It can be stored outside. It oxidizes a bit, causing fine grades to stick together. Washington Mills is the source. It comes in 50 pound bags and bulk bags. Rated at 90% SiC. Plenty good for tumbling. It is mixed when melting steel so steel mills would be main consumer. Part number is Carbolon SC. I bought $300 worth, about 1000+ pounds at a Birmingham steel mill supply, or that is what it looked like. I don't remember the name of the distributor. 1000+ pounds was about all my pick up truck wanted to carry. Doubt they would ship from that location. They did not seem to want to fool with me nor my piss-ant purchase of 1000 pounds. I think they did me a favor selling to me.
SDR 17 and SDR 11 are the most commonly used HDPE pipe sizes and so the cheapest. I chose the SDR 17 because my local pipe supplier stocked it. If you are a thick freak you can go with SDR 11. I prefer the 6" i.d., 5" is getting small for my tumbling goals. 7" i.d. would actually suit me best. Diameter to rock size ratio controls my fast rotation tumbling method.
As far as making HDPE barrels to sell I found a machine shop to machine plate into circles in 100 qty at a great price. This would eliminate the need to buy expensive end cap and reducer fittings and drop manufacturing cost to under $20/6" barrel for a decent re-sale price. But it would require a custom made welding machine that will be a challenge to build. A project set aside for another day. It would have a 4" snout so that an easy-access 4" rubber Fernco cap can be used. Probably market it on EBAY.
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jamesp
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Post by jamesp on Jun 30, 2020 6:21:23 GMT -5
Wowzers, almost a 3" wall for a 20" pipe! My buddy did some 12 inch OD with 8 inch ID. 2 inch wall thickness. He got the pipe for free. He tapped and screwed the caps on. But has to remove about 12 nuts to access. And they weigh a lot. Too heavy and too much time to access for me. I like the 6" Fernco rubber caps for 8" or bigger barrels. Easy to make inspections. Thick. Big rock access. And the expand out to near 4 inches like a balloon when tumbling gaseous loads preventing blow outs. Probably the ultimate barrel would be my 8" SDR 17 barrels with the 8x6 reducer and a 6" Fernco cap. I have 4, each is 2 inches shorter so I can transfer a load to the next smaller barrel without adding rocks midstream. And have a barrel near a chosen batch size of like 9-12-15-18 pounds.
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entropy
having dreams about rocks
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Post by entropy on Jun 30, 2020 16:57:26 GMT -5
I paid a visit to the piping supply yard. The HDPE fittings are discouragingly expensive – it’s not going to happen on my budget. They did have 8” DR-11 and 4” DR-11 pipe in stock ($13.70 per ft and $3.97 per ft respectively). The problem is I had to purchase full length sticks (24’ of the 8”, and 20’ of the 4”). They would not cut & sell the pipe in smaller sections. My bandsaw is a Grizzly G9743. The blade is cobalt steel (alloy Q601 VTH Plus M42), sized 1” wide x 0.035” thick, with 3-4 tooth pitch. This is rather aggressive metal-cutting blade intended for cutting thicker sections of alloy steel. You can see in the picture that I was recently cutting 5” x 3/8” steel angle, and 4” x 8” x 3/8” box-tube. Normally I set my saw on its lowest speed (158 feet/min) and use water for coolant - with a little bit of Koolmist added to cut down on corrosion. The saw is setup/dedicated for cutting steel. My first attempt at cutting HDPE however: I set the blade on the fastest speed setting (308 feet/min). The purpose of the coolant is to keep the blade teeth cool – specifically to prevent tempering of the blade. There’s zero chance of any plastic chips hitting 1000 degrees F & damaging the blade – thus I turned off the coolant. Do not turn off the coolant! The blade will cut about 1/2” into the pipe, the friction will heat up the plastic, and things become a sticky mess. Simply put – it cuts like crap without coolant. With the coolant flowing however, HDPE cuts like butter. About 40 seconds per cut. I ended up parting the 24 foot piece of 8” NPS HD-11, into (qty 15) pieces at 19” each. It took about 30 minutes from start to finish. I had one short piece of scrap left over, which I’m going to practice welding on. I haven’t touched the 4” pipe yet. You can see that the bandsaw cuts are clearly visible on the HDPE ends. From reading manufacturer’s recommendations for welding HDPE – you want a smooth & flat surface for welding (to achieve optimum/uniform heating, and no entrapment of air bubbles). I’m going face the ends on the lathe. I have no idea how well this material will cut using carbide-insert tooling. My assumption is that I’ll have to use coolant and turn it fast. I watched videos of the dedicated HDPE pipe-welding kits, and the surfacing cutters typically turn slow with brute-force - like a cheese grater. I might have to sharpen some custom cutting bits from HSS with an aggressive rake. I’m brainstorming ideas for my tumbler-chassis (a skid-mounded design) – one that will be able to turn multiple barrels at once (go big or go home). I have a bunch of 2.5” NPS Schedule 10S pipe in 304L stainless that would make excellent rolling bars. They’re lightweight, with plenty of bending inertia to support the load of multiple barrels at once. They don't need paint, and they'll never rust. Lastly – I am not selling any HDPE barrels, tumblers, or anything. I’m a home hobbyist. The shop is my playground – not my job. . .
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EricD
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Post by EricD on Jun 30, 2020 17:40:29 GMT -5
I would love to have the opportunity to work in a shop like yours with tools like you have. You have excellent and very clean workspace/tools. I like the way you do things! Your lathe is WOW
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rockstock
spending too much on rocks
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Post by rockstock on Jun 30, 2020 20:57:57 GMT -5
I wanna see more of that shop, super cool!
Are you planning on creating those 15 cuts into barrels to run all at once? That is a good goal (in my mind anyways lol)
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jamesp
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Post by jamesp on Jul 1, 2020 4:54:12 GMT -5
I'm moving in to the back of your shop permanently entropy. If I had your equipment I would make and sell HDPE barrels. Don't concern yourself with me. The rock tumblers of the world need these barrels ! Yes the fittings are costly. If I were to open a commercial jobber shop and do contract tumbling say for metal/ceramic/rock I would use that same SDR 11 8 to 10 to 12 inch pipe. Tumblers would be std 10 foot long 1.5 to 2 inch cold rolled shafts with 4 bearings 8' apart. No internal bearings. No stacking to avoid blow outs on lower shaft bearings. If you can figure out how to weld plate to pipe you are in business for cheap barrels. Obtain some plate and cut circles using that monster lathe ! I found a guy to do the 6"x1/2" end plates for $6 each including HDPE in 100 qty. I got my pipe for free from plumbing contractors that had various cut offs. They hate disposing of HDPE pipe remnants. But I never used the pipe as I was going for the quickest and easiest. The 6 and 8 inch reducers and end caps were long enough. I just spent the money on the fittings, fairly cheap at a giant Alabama HDPE supply house hdpepipeco.com/HDPE_Pipe.htmlI actually cut the fittings shorter in 1.5" to 2" increments to make stepped sized barrels. 4-6" and 4-8" from 6 to 18 pound capacities. The biggest 6" and 8" barrels were made by leaving the fittings full size. Bet you could have an HDPE contractor do your welding for you on his welding machine. I cut my fittings using a $100 table saw with a 10" carbide trim blade with like 40 teeth. Blade set low to 1 inch cut zone. I clamped a pair of rollers on each side of the blade, lined them up, and let the blade rotate the fitting as it cut. Holding feed speed by hands on fitting. I practiced on pipe to get the rollers lined up. Be cautious doing this. Cut must be good to get good weld. As far as welding, cut some of that pipe up into say smaller 3"x3" 'blocks' and practice welding them on a stove top with teflon frying pans. Too hot or too cold and it will not weld well. seems 350F to 375F is the sweet spot. Heat slow and deep. Wait for it to bead at contact point. Push down on them to see if the ends are just starting to be like putty. Lift them to see if contact is 100%. On my third attempt I nailed it. 12 pound sledge hammer test would not break the weld. Incredible weld force when sweet spot is hit. You will like your poly barrels. Do Fernco caps ! Remnant pipes at lower right
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entropy
having dreams about rocks
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Post by entropy on Jul 1, 2020 20:02:10 GMT -5
I just ordered a 4’ x 8’ sheet of 1” thick black HPDE pipe-grade. Cost was $357. I had to pay 60 dollars extra for freight (from Texas to Seattle) – where I pick up at the Seattle terminal. The true cost (with freight) was $417. I should be able to cut (qty 44) 9” rounds from the sheet (completing my 15 barrels, with leftover).
Interesting discussion with the sale’s man. The black pipe-grade HDPE (which needless to say they make pipes out of) is the best it gets. Top-shelf material - very dense, loaded with UV protection. Or so I’m told. I wanted to ensure the entire tumbler was UV protected (of the same material) – thus I opted for the pipe-grade sheet. I figure the 1” would be advantageous (0.200” thicker than the barrel) – considering the wear seems to occur most in the center of the endcaps (using the PVC tumblers for comparison). The next size up was 2”, and that seemed excessive. The next size down was 3/4" - which is thinner than the pipe.
More interesting comparisons/observations: The 8” SD-11 pipe contains 5562 cubic inches, which equals a cost of 5.9 cents per cubic inch. The 4” SD-11 pipe contains 1262 cubic inches, which equals a cost of 6.3 cents per cubic inch. The 4’ x 8’ x 1” sheet contains 4608 cubic inches, which equals a cost of 7.6 cents per cubic inch. (or 9.1 cents – if you include the terminal charge. Too bad it wasn’t on the shelf in Seattle) The density of HDPE is 59.93 lbm/ft^3, or 0.0347 lbm/in^3
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entropy
having dreams about rocks
Member since June 2020
Posts: 71
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Post by entropy on Jul 1, 2020 21:41:41 GMT -5
I hope the pictures I posted earlier in this thread didn’t disappear. I’m having issues with the photo-host I’m using (user-error type issues). I accidently deleted the pictures, but they seem to still be loading here??? Briefly going back to the beginning of this thread: I purchased the piece of scrap steel shown below. It started out 200 feet long. It’s a pier column, used for constructing large buildings over the water. You drive a bunch of these pipes into the bedrock (90 to 120 ish feet-deep water), and then you trim the tops to get them all the same height. This is one of the trimmings. It’s 4-foot diameter, 1” wall, medium strength steel (51 ksi yield). This piece weighs about 3600 pounds. I’m going to build a gun safe out of it. The safe will be full-tweaker-proof. I also picked up a smaller piece from the same construction project – a 30” diameter, 3/4" wall piece, about 1200 pounds (not shown). This smaller piece was the original subject-of-discussion for this thread. The small pipe became the subject of discussion, because I needed to remove the paint from my large 4 foot diameter pipe. I’m quite discouraged at the thought of using a needle gun, or grinder, for literally hours. So I contacted the blasting supply company and discussed my options. She recommended 16 grit brown aluminum oxide, with a 50 SCFM blast gun. Problem – my current compressor does 18 SCFM on a good day. So I designed and built the air compressor shown below. It’s skid-mounted, so I can move it with my forklift. It will easily hit 50 SCFM. It even has an integral moisture separator. I modified the air cleaners accept off-the-shelf shop-vac filters (the small size). Electrical contactors are 80 amp. So I’m out purchasing my first bag of aluminum oxide blast grit, and the customer before me is purchasing silicone carbine for stone tumbling. I came home, did some internet searching, found this site, purchased a 15 pound rock tumbler, and that’s how I'm here - and that's how I had a crazy idea to build a 30 diameter tumbler out of steel (which I'm glad you guys talked me out of doing. . . . )
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entropy
having dreams about rocks
Member since June 2020
Posts: 71
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Post by entropy on Jul 1, 2020 22:25:26 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 Jul 2, 2020 0:02:18 GMT -5
Getting back on topic - above is Jamesp’s photo linked from another post. Appreciable wear occurs at the center of the end-cap (because of a higher velocity-of-slip at this location). Hopefully this issue is fixed by having 1” thick HDPE caps. I’m wondering however – there also appears to be appreciable wear within the 4” section of the tumbler barrel. See below link. Green is the rubber cap. Blue would represent a solid HDPE plug, with lip (to keep it literally from entering the barrel. The water seal would remain via green cap. The blue plug however would keep the tumbling “business” within the barrel only – virtually eliminating wear in the 4” section (which is only half the thickness of the 8” pipe. Good idea? Yes, no? Also, I’ve been reading on how to cut the 1” thick sheet of HDPE. Most online recommendations are a jigsaw, using an aggressive wood blade, on half-speed. And get this - most plastic outfits that I called wouldn't tell me squat - other than they'd cut it for me. errrrrr . . .. So if the jigsaw works, great. If it’s a pain in the butt, I was considering building a punch press, machining some dies from 4340. HDPE has a shear strength of about 4800 psi, and a UTS of 6300 psi. This means a 9” diameter plug can be punched out of 1” sheet using approximately 75 tons of force. This is achievable with a single 8” hydraulic ram at 3000 psig. Building a compact 75 ton punch-press would add more cost to this project, but it would make cutting end-caps super fun – and I’d have a cool punch press when I’m done. I think I’m going to try the jigsaw first. No need for unnecessary tangents. The barrel is 8.625” OD. I’m going to make the end-caps 9” (because I can’t cut a perfectly round plug by hand with a jigsaw, and even punched disks will have a slight taper on-end - nor can I weld a cap perfectly centered on the pipe axis). Thus after welding, I’ll trim the end-caps flush with the OD of the pipe, on the lathe. It will look super clean.
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entropy
having dreams about rocks
Member since June 2020
Posts: 71
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Post by entropy on Jul 2, 2020 2:38:04 GMT -5
Jamesp, I was thinking about your idea for 10 foot bar spacing. I did some calculations. Generic bars are shown in the sketch, at 10 foot spacing. A “very heavy” tumbler barrel of weight (w) is placed in the center (representing the weight required to bend the bars). An interesting design consideration is the angle in which the bars make with the center-axis of the barrel. Too narrow of angle, the barrel might tip off. Too wide, and you can imagine the barrel slipping between the bars. I did a calculation for 30 degrees, 45 degrees, and 90 degrees. You can see that the resultant force applied to the bar increases with a given barrel weight - as the angle increases. My assumption is that for a real-world application, you’d probably want something between 30 and 45 degrees. Once you pick your bar spacing, the in-service angle becomes a function of barrel diameter you're running. But I digress. A pair of 1.5” solid steel bars (10 foot each) will weigh 121 pounds total. A pair of 2” solid steel bars will weigh 216 pounds total. A pair of 2.5” NPS Schedule 40 pipe will weigh 117 pounds total. For the 1.5” solid steel bars, the tumbler weight required to bend the bars (assuming 36 ksi yield): 707 pounds at 30 degrees 674 pounds at 45 degrees 502 pounds at 90 degrees For the 2” solid steel bars, the tumbler weight required to bend the bars (assuming 36 ksi yield): 1713 pounds at 30 degrees 1634 pounds at 45 degrees 1225 pounds at 90 degrees For the 2.5 NPS Schedule 40 pipe, the tumbler weight required to bend the bars (assuming 36 ksi yield): 2408 pounds at 30 degrees 2301 pounds at 45 degrees 1747 pounds at 90 degrees This is the force required to actually bend the bars. You’d need to cut all these weight values in half - to avoid cyclical fatigue concerns. I would cut the values by 2/3 – for extra safe & reliable design. Observations: pipe is way cheaper than solid bar, and is actually appreciably stronger – weight for weight - provided you take advantage of larger roller diameters.
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