Where to source pulleys for a motorized grain mill? And question on RPM...

[max384]

I'm about to pull the trigger on a Monster Mill MM3 with 1 1/2" rollers.

I am going to motorize it with this 1/2 HP electric motor.

I have found this 1 1/2" pulley for the motor side.

However, I'm having trouble finding a 1/2" bore 12" to 15" pulley for the mill side. I don't know if my Google-fu is weak today, or what, but I am just striking out. Does anyone have any links to a pulley of this size?



And on a side note, does anyone have any opinion on the RPM of the rollers? At 12", the approximate speed would be 220 RPM. At 15" the approximate speed would be 175 RMP. I'd rather keep the mill side pulley as small as possible, but of more importance is a good crush... so what speed is best?

 

[mblanks2]

http://www.grainger.com/product/CONGRESS-V-Belt-Pulley-3X938?s_pp=false&picUrl=//static.grainger.com/rp/s/is/image/Grainger/3X918_AS01?$smthumb$

220 RPM is fine

 

[max384]

Thanks for that link!

I'm worried about too much floor with too fast of a roller speed. You don't think that's a concern with 220rpm?

 

[mblanks2]

Thanks for that link!

I'm worried about too much floor with too fast of a roller speed. You don't think that's a concern with 220rpm?

Quote from Crankenstein website: A 12" mill pulley and a 1.5" motor pulley gets a 1725 rpm motor down around 200 rpm on the mill. 1/4 hp should do it for the homebrewing mills.

This is the set-up that I use. Get some flour with a .029" gap but not excessive.

 

[Twotaureanbrewing]

Is 200rpm what you guys would recommend?

Manufacturer info on the mills recommend 300-400rpm

 

[max384]

Quote from Crankenstein website: A 12" mill pulley and a 1.5" motor pulley gets a 1725 rpm motor down around 200 rpm on the mill. 1/4 hp should do it for the homebrewing mills.

This is the set-up that I use. Get some flour with a .029" gap but not excessive.

Thanks for this information. It looks like this setup is the way to go. Although I just noticed this is for the Crankenstein, not the Monster Mill... But I'd imagine they're all pretty similar in power requirements...

 

[max384]

Is 200rpm what you guys would recommend?

Manufacturer info on the mills recommend 300-400rpm

This is from the Monster Mill website:

The best speed to run all of the drill driven mills at is around 150-250 rpms. Does it have to be exactly 200 rpms? NO WAY. A range of 100-300 is fine, and if you are willing to have a little more flour, then you can run it a little faster. I generally tell folks to run it as slowly as your drill will run it without stalling plus a little more. It usually takes a little more torque to get the mill going than to keep it going, so you will have to give it some more power to start the mill, and then slow it down once you are milling. You should experiment with faster/slower speeds and see what it does to your grain.

They also mention this:

This is a very complicated answer. We recommend you use at least a 1/2 HP motor for our small 1.5" diameter roller mills, and 1 HP for our larger 2" diameter roller mills. Use a capacitor start motor if possible. They have much higher starting torque and should be able to start milling after the hopper is loaded. If you don't have a capacitor start motor, you may just have to have the mill running when you load the hopper. Get the RPMs down as much as possible. To do this you will need to use as slow a motor as you can get, and put a very small pulley on it, and put as large a pulley as possible on the mill. The biggest problem with this approach is that the pulleys end up being very large.

Most AC motors run at the slowest speed of 1725RPMs. This means that you need to reduce the speed by a minimum factor of 10. So you will need a mill pulley that is 10 times the diameter of the pulley on the motor to get down to 172.5 RPMs assuming your motor runs 1725 RPMs. When using pulleys to drive the mill it may be preferable to widen one flat on your mill's drive shaft using a metal file. The flats are designed for drill driving, and will work better with a pulley setscrew if they're wider. This is easily accompished using a metal file with the drive roller held firmly in your bench vice.

http://www.monsterbrewinghardware.com/store/pc/FAQs-d2.htm

Since this is the mill I'm going to be buying, I've been using this as guidance for motorizing the mill.

However, I'd also be curious to hear other's personal experiences with other roller speeds.

 

[cubalz]

I have a Monster Mill 3 and am running a 1750 rpm motor with 12" and 2.5" sheaves. This got me to around 180 rpm. It works perfectly. Bought my sheaves from Zoro.com

The lower the rpm, the better.

 

[max384]

I have a Monster Mill 3 and am running a 1750 rpm motor with 12" and 2.5" sheaves. This got me to around 180 rpm. It works perfectly. Bought my sheaves from Zoro.com

The lower the rpm, the better.

Wouldn't this combination of pulleys give you about 365 rpm?

http://www.blocklayer.com/pulley-belteng.aspx

 

[Yesfan]

I have a Monster Mill 3 and am running a 1750 rpm motor with 12" and 2.5" sheaves. This got me to around 180 rpm. It works perfectly. Bought my sheaves from Zoro.com

The lower the rpm, the better.

If everyone else is shooting for the 200-300, then why would 180 or lower be better? Is it more the diameter of the rollers (1.5") vs a 12-15" pulley on the mill end?


Just asking as I think a MM is something I'd like to have, but that's down the road.

 

[cubalz]

Wouldn't this combination of pulleys give you about 365 rpm?

http://www.blocklayer.com/pulley-belteng.aspx

Yeah sorry. I meant to say 1 1/2" pulley on the motor. Brain fart

 

[max384]

Yeah sorry. I meant to say 1 1/2" pulley on the motor. Brain fart

Okay thanks. I think 1.5" and 12" pulleys are what I'll be getting.

Thanks for the help everyone!