What size motor?

[KruseMissile]

Im gonna try and build a 5 gallon star roller(from the tut. on passfire), but i was wondering what size of motor i need. I was thinking either 1/4 or 1/3 hp. Everything else is easy to get, only need to find a good motor. Also will it need to have alot of torque(if i were to use a light dimmer switch if will effect torque)? Here is the link to the tutorial. http://www.passfire.com/archives/issue4_3/design4_3_2.asp Thanks

[Swede]

I'd go with a 1/3HP or more. Sub hp motors really aren't all that much different in price, so if there is a choice, and the price diff is minimal, I'd get the bigger motor. They run cooler, loaf along, and at start-up especially won't pull a massive amount of current. Heck, RPM is RPM, and if a 5 hp motor turns at 1725, it'd make a great roller.

 

Good luck!

[Arthur]

You will need to get close to optimim RPM with pulleys or gears before you try speed variation using lamp dimmers, the dimmer may not like it the motor may not like it either.

 

The favoured UK option is the DC motor off a golf cart or wheelchair -preferably one that goes straight from DC in to wheel speed output, even better if you can get the motor controller with it.

[Swede]

I didn't even notice the dimmer part of the question. Lamp dimmers really will not work. As Arthur said, you'll need either a DC motor, or if you want a killer setup, find a 1/2 HP 3-phase motor, and use a VFD (Variable Frequency Drive) to power it. Not cheap, but you'll have true Dial-a-speed and good torque too. Either way, a true speed controller for a small DC motor of 1/4 to 1/3 HP will be $75 at least, used, unless you can scrounge one free, and a VFD is $200+. There's a reason industry makes and uses these expensive speed control devices - simple rigs like lamp dimmers don't work.

[KruseMissile]

I found this one. http://cgi.ebay.com/ws/eBayISAPI.dll?ViewI...e=STRK:MEWAX:IT using a 2" pulley to a 8" pulley will give me 107 rpms(if i did the math right) which is about where i need it for good size batches but i can alway change the size of the pulley by using a wood pulley(connected to the barrel). If i were to cut the circle for the second pulley and made it lop sided would it bounce the stars?

[Swede]

I found this one. http://cgi.ebay.com/ws/eBayISAPI.dll?ViewI...e=STRK:MEWAX:IT using a 2" pulley to a 8" pulley will give me 107 rpms(if i did the math right) which is about where i need it for good size batches but i can alway change the size of the pulley by using a wood pulley(connected to the barrel). If i were to cut the circle for the second pulley and made it lop sided would it bounce the stars?

 

THAT looks like a very nice motor. I have seen motors half that size with a higher HP rating, but HP ratings are very deceptive. There is no substitute for beef, and such a motor as that would probably do fine, especially geared down with sheaves. My lathe has a motor about 2 feet in diameter - it is a physical monster - yet it is rated at only 1.5 HP. Larger diameters typically equate to more torque. You could always fit one of those multiple sheaves like you'd see in a drill press, and set up the system so that you can swap the belt between pullies for different speeds.

 

Anyway, it looks good, the price is excellent, and I'll bet it would make a fine ball mill motor too for a smaller mill. He apparently has a lot of them. I think I'll pick one up too. Nice find!

[KruseMissile]

yeah, they look like terrific motors! Im waiting for mine to come in, its been 1 and a half weeks so it should be here soon. Ill make the 2nd pulley out of wood(as described in the passfire article). But if i cut the pulley a little bit lop sided would it bounce the stars? or do i need to attack the barrel off-center?

[andyboy]

Making the pulley loop-sided will only make the belt come of.

 

I would suggest against making it bounce before you see how it behaves without the bounce, personally I find the bouncing redundant.

[KruseMissile]

yeah, good idea, i might not need the bounce anyways. Thanks!