BeerSmith™ Home Brewing Forum

Brewing Topics => All Grain/Advanced => Topic started by: sdsmith4u on October 28, 2013, 10:28:00 AM

Title: Grain mill speed
Post by: sdsmith4u 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?
(http://s23.postimg.org/3mz9sfgg7/image.jpg) (http://postimg.org/image/3mz9sfgg7/)
Title: Re: Grain mill speed
Post by: grathan 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).
Title: Re: Grain mill speed
Post by: sdsmith4u 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.
(http://s24.postimg.org/sgasx1jsx/Power_Grinder_5.jpg) (http://postimg.org/image/sgasx1jsx/)
Title: Re: Grain mill speed
Post by: merfizle 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
Title: Re: Grain mill speed
Post by: Scott Ickes 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.
(http://s24.postimg.org/sgasx1jsx/Power_Grinder_5.jpg) (http://postimg.org/image/sgasx1jsx/)

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!
Title: Re: Grain mill speed
Post by: Mtnmangh 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.
Title: Re: Grain mill speed
Post by: mbg-bs 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
Title: Re: Grain mill speed
Post by: Scott Ickes 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.
Title: Re: Grain mill speed
Post by: Mtnmangh 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.... ;)
Title: Re: Grain mill speed
Post by: gevans 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.