Motor for a mill
Posted: Wed Oct 25, 2006 8:13 am
by Techie101
I've been doing some reading on gear ratios, torque, etc. and i've got a few questions...
Most people seem to buy a large motor (in terms of what it will be used for) and will "gear down" as in get one that does 1500+ RPMs and will gear it down to ~150 RPMs.
What would be the issues of gearing one up? As in getting a motor that does 70 RPMs and give it a 1:2 (or is it 2:1) ratio so that the mill is run at 140 RPMs.
I have a small motor out of a kitchen applilance (juicer) that has a gear/pully/sheave/whatever it's called on it that spins at 35 RPMs and is about 4" in diameter. If I put a gear on the mill that is 1" in diameter it would turn the mill at 140 RPMs, correct? I'm not sure of the torque, but I do know that while the motor is running I can grip the gear and my hand is in serious discomfort before I can tell the motor is stressing any.
Re: Motor for a mill
Posted: Thu Oct 26, 2006 7:40 am
by Steve
Techie101 wrote:I've been doing some reading on gear ratios, torque, etc. and i've got a few questions...
Most people seem to buy a large motor (in terms of what it will be used for) and will "gear down" as in get one that does 1500+ RPMs and will gear it down to ~150 RPMs.
What would be the issues of gearing one up? As in getting a motor that does 70 RPMs and give it a 1:2 (or is it 2:1) ratio so that the mill is run at 140 RPMs.
I have a small motor out of a kitchen applilance (juicer) that has a gear/pully/sheave/whatever it's called on it that spins at 35 RPMs and is about 4" in diameter. If I put a gear on the mill that is 1" in diameter it would turn the mill at 140 RPMs, correct? I'm not sure of the torque, but I do know that while the motor is running I can grip the gear and my hand is in serious discomfort before I can tell the motor is stressing any.
Actually on a mill you want it to be geared to a low speed. If you change the speed to allow it to turn or feed faster it runs the risk of binding up because it will also step down the torque at the same time. A nice slow controlled feed will give you more control and consistant results.
Steve
Posted: Mon Oct 30, 2006 12:18 pm
by Techie101
Right, the ideal speed seems to be between 150 to 200 RPMs. I was actually wrong in my first post, the motor turns at 70 RPMs (I counted 35 rotations in 30 seconds). I may give this one a try and see what happens.
Posted: Mon Oct 30, 2006 12:38 pm
by Homegrown Hops
I plan to build a mill table one day, but am still using my 5amp Skil 1/2" drill to power my JSP.
HH
Posted: Tue Oct 31, 2006 5:21 am
by DannyW
Other than the speed at which your bucket fills, what are the effects of milling too fast or too slow? Is there any reason not to run it as fast as it will go?
Posted: Tue Oct 31, 2006 6:31 am
by bub
Higher speeds can sometimes Tear instead of crush the grain... this can lead to sparging difficulties.
BUB
Posted: Tue Oct 31, 2006 6:36 am
by DannyW
Oh, OK. I hadn't noticed a difference with my single roller Philmill, but haven't been really watching for it either. Only thing I've reliably noticed between speeds is that the drill gets hot if I go slow and the mill body gets hot if I go fast!
Posted: Tue Oct 31, 2006 7:38 am
by Homegrown Hops
DannyW wrote:Other than the speed at which your bucket fills, what are the effects of milling too fast or too slow? Is there any reason not to run it as fast as it will go?
High speed milling= cloudy beer
I used to crush with a crappy high speed drill and a few brews got crushed at high speed, the amber beer I made from the grain turned out looking like a milkshake and never really cleared at all. I drank it anyway and it tasted fine but looked horrible.
HH