killerq
starting to shine!
Member since July 2023
Posts: 33
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Post by killerq on Jul 18, 2023 23:12:46 GMT -5
So,
I feel that the 1/2” shafts that I’m using may simply be a tad too flimsy at the 36” lengths that I’m running them at. I feel that 3/4” will be much stronger. Even with a 3lb barrel, when it’s in the middle of the shaft, it had minor flex - I’d like zero flex.
I’ll order new 3/4” bore pillow block bearings. My motor has a 1/2” shaft and is 1725 RPM. I believe I should be shooting for around 50 RPM for the barrel.
What is the best online calculator to use to determine the two pulleys I’ll need for the motor shaft and main drive shaft? My barrel is 4.25 inches in diameter (the standard, 3lb barrel).
Thanks!
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Post by aDave on Jul 19, 2023 0:51:03 GMT -5
I don't know if this will help, but I sent this to another member not too long ago. Don't know if it's the "best," but perhaps you can make it work for your situation. www.blocklayer.com/pulley-belteng
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killerq
starting to shine!
Member since July 2023
Posts: 33
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Post by killerq on Jul 19, 2023 7:31:25 GMT -5
I think you just plug in the same diameter pulleys you've already been using and just find 3/4" bore holes for that size, right? I'm plugging in 1" diameter pulley on the motor (which is probably already impossibly small) and 12" diameter on the drive shaft (a dinner plate) and still calculating 146 rpm. The calculator maxed out at 24" diameter on the drive pulley but was still 73 rpm. How did you do this the first time? If you haven't bought the new motor yet, maybe 1725 rpm isn't the right choice. There must be a motor out there that's higher torque lower rpm that wouldn't need such a huge contrast in pulleys to slow it down. As close to 50 rpm would be ideal. I think this is the reason why your barrel is slipping on the shafts. Your drive shaft is probably rotating at hundreds of rpm currently and the barrel is just happening to rotate at its own speed while slipping. Thanks! There is no slippage anymore now that I have both shafts actively driven - so the actual rpm of my 3lb barrel right now is right around 50 - so that’s great. I’ll let you know what I come up with for sure.
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killerq
starting to shine!
Member since July 2023
Posts: 33
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Post by killerq on Jul 19, 2023 13:55:49 GMT -5
Thanks! There is no slippage anymore now that I have both shafts actively driven - so the actual rpm of my 3lb barrel right now is right around 50 - so that’s great. I’ll let you know what I come up with for sure. Are you sure? How are you determining that the barrel is both not slipping and at 50 rpm? At 50 rpm you would be able to look at the shaft and count "one, one thousand, two, one thousand" for each rotation of the shaft. When I look at the drive pulley and drive shaft in this video, it is spinning much faster than 50 rpm. I had to slow the video down to 25% to even count but it looks like at least 2 revolutions per second at 25% so I would estimate like 480rpm. What are the diameters of the pulleys that you have now? You can use the calculator aDave linked to see how fast it's actually going. Oohhh. I see what you mean. Since I saw the barrel consistently rolling and not slipping itself. I figured it was all good. Here’s a video in slow motion for you. I think the fox here would be a slightly larger pulley on the main roller shaft, right? I currently have a 6”. Here you go - nice and slow. I really don’t see any slipping. odysee.com/slowmotionvideo:bI think that I am going to stick with 1/2” shafts for now - everything seems to be working. Lemme know what you think. I just saw your update - so that video I posted should still help
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Post by Rockoonz on Jul 19, 2023 14:28:58 GMT -5
For barrel calculations I start with outside diameter times pi to get circumference. If 50 RPM is the goal, then C x 50RPM to get surface speed, then do in reverse to determine shaft RPM needed to get that surface speed. The important thing is to save that surface speed somewhere for reference if you like the results, as it saves a few steps if you make a new base with a different diameter shaft, or add hose or something to your shaft and change the diameter. Other important thing is that surface speed is the same, pretty much for all diameters of barrels, unlike RPM, so it's a better number to use for calculations. 55.6 SFPM is the ~ speed of the outside of a 4.25 barrel at 50rpm. A 2" motor pulley and 12" shaft pulley on a 3/4" shaft gets you pretty close.
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