Author Topic: Grain mill speed  (Read 15689 times)

Offline sdsmith4u

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Grain mill speed
« on: October 28, 2013, 10:28:00 AM »
What is the best speed (rpm) to turn a grain mill? Is 240 rpm too fast? Is 180 rpm too slow?


Offline grathan

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Re: Grain mill speed
« Reply #1 on: October 28, 2013, 12:31:19 PM »
I really don't see why speed matters. I'd say keep going faster until you don't see a difference in crush speed, then back it off %25. Other than that it would depend on the manufacturer (perhaps the bearings are only rated up to a certain speed).

Offline sdsmith4u

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Re: Grain mill speed
« Reply #2 on: October 28, 2013, 03:24:33 PM »
Thanks.  I am turning my Monster mill at 240 rpm with my PowerGrinder.org 1/2 hp motor which has a 7.5:1 reduction.  Monster recommends a rpm of roughly 200 rpm, but I don't know if their recommendation has to do with mechanical capacity (bearing max speed) or grain crushing efficiency.  If you have had good luck with grinding speeds of over 240 rpm, I won't worry about 240 rpm being too fast.  Thanks again for the reply.


Offline merfizle

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Re: Grain mill speed
« Reply #3 on: October 28, 2013, 04:31:04 PM »
I have found speed does matter.  I set the drill revs to as fast as it takes to turn the rollers.  I have found that my mash and lauter eff are better doing it that way.  I'm currently getting around 80-85% brewhouse efficiency.

Mark
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Offline Scott Ickes

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Re: Grain mill speed
« Reply #4 on: October 28, 2013, 05:19:55 PM »
Thanks.  I am turning my Monster mill at 240 rpm with my PowerGrinder.org 1/2 hp motor which has a 7.5:1 reduction.  Monster recommends a rpm of roughly 200 rpm, but I don't know if their recommendation has to do with mechanical capacity (bearing max speed) or grain crushing efficiency.  If you have had good luck with grinding speeds of over 240 rpm, I won't worry about 240 rpm being too fast.  Thanks again for the reply.


Besides being a homebrewer, I'm also the Service Engineering Representative for Timken (bearings) here in the pacific nw.  This probably has ball bearings in it.  240 rpm is childs play for a ball bearing.  A ball bearing can easily handle speeds of 2000+ rpm.  240 rpm is considered a slow speed environmnet for a ball bearing. 

If you double the speed of a bearing, you cut the bearing life in half.  If you double the load on a bearing you cut the life by 90%.  So, increasing the speed of this machine, won't have a noticeable affect on the bearings.  You'll crush just as much grain with it at high speeds as low.  You'll just crush it faster at 240 rpm.  If you increase the crush enough, you might start causing issues with the bearings, but I doubt it.  It's crushing grain, not rolling out hot steel.

Run it as fast as you want to run it.  You'll be just fine!
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Offline Mtnmangh

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Re: Grain mill speed
« Reply #5 on: October 28, 2013, 07:22:31 PM »
Besides being a homebrewer, I'm also the Service Engineering Representative for Timken (bearings) here in the pacific nw. 

Interesting....We have a warehousing facility that houses Timken Products and direct ships them just down the road from where I work.
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Offline mbg-bs

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Re: Grain mill speed
« Reply #6 on: October 28, 2013, 07:30:02 PM »
Years ago when I motorized my mill the recommendation was 300RPM. My gear motor runs at 325RPM and have had no problems with efficiency or my BarleyCrusher.

Mike

Offline Scott Ickes

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Re: Grain mill speed
« Reply #7 on: October 28, 2013, 10:00:00 PM »
Besides being a homebrewer, I'm also the Service Engineering Representative for Timken (bearings) here in the pacific nw. 

Interesting....We have a warehousing facility that houses Timken Products and direct ships them just down the road from where I work.

Let me guess.  Crossville.
Kegs:
 Red IPA
 ESB
 Saison Solera
 Dubel (Aged in Malbec Wine Barrel
Aging:
 80 Shilling (In bourbon barrel)
Bottled
 Peppermint Patty Stout
 Wee Heavy

Scott Ickes
https://creativebrewing.wordpress.com

Offline Mtnmangh

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Re: Grain mill speed
« Reply #8 on: October 29, 2013, 07:53:03 PM »
Besides being a homebrewer, I'm also the Service Engineering Representative for Timken (bearings) here in the pacific nw. 

Interesting....We have a warehousing facility that houses Timken Products and direct ships them just down the road from where I work.

Let me guess.  Crossville.

That's where I be.... ;)
Drinking: Belgian Golden Strong ale
              Step Up Porter
              Oktoberfest
               Brown IPA

Primary:  Step up Porter

Secondary: nada

Offline gevans

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Re: Grain mill speed
« Reply #9 on: November 05, 2013, 03:39:36 PM »
Barley Crusher states up to 500 RPM for their crushers.  I run mine with a mounted low speed drill and have never had any issues.