What RPM do you run your grain mill at?

BrewBeemer said:

What about adding a 3/8" diameter rod parallel to the rollers above them
in the hopper, add a throttle plate the width of the hopper where it's located plus the full length of the hopper. This way you will be able to restrict the grain flow to the rollers vs compacted by the grain weight in the hopper plus still utilize the mills full roller width.
Think an hourglass, you have flow but reduced as an example.

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Like my mill?

Well, tested the mill.... 90 inch pounds still isnt enough.Well, tested the mill.... 90 inch pounds still isnt enough.

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To me your torque requirement sounds too much.
My mill does not come close to 30 in/lb running torque.
I would measure the torque requirement of your set-up without grain first, should be very low.

Cheers,
ClaudiusB

ClaudiusB said:

Like my mill?

To me your torque requirement sounds too much.
My mill does not come close to 30 in/lb running torque.
I would measure the torque requirement of your set-up without grain first, should be very low.

Cheers,
ClaudiusB

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Perfect!
Now slip tubing over the rod screwed to the rod on one side to produce an eccentric adjustment to vary the feed restriction.
That looks like 3/8" rod by the picture (guessing here), add 3/4" tubing with external arm to adjust and lock the setting.

What is the dimensions of your hopper, angles, height plus how many pounds will it hold?

The free running torque is pretty much not measurable... besides the fact that I have no way to measure it. But it spins freely by hand.

Dry grain runs just fine, no issues what so ever, it's after the grain has been conditioned that's the issue. It might also be my impatience and running the grain while it's still a little damp after conditioning.

shushikiary said:

The free running torque is pretty much not measurable... besides the fact that I have no way to measure it. But it spins freely by hand.

Dry grain runs just fine, no issues what so ever, it's after the grain has been conditioned that's the issue. It might also be my impatience and running the grain while it's still a little damp after conditioning.

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You can use a fish scale and a string to do it.
Measure the motor current to see how close you are to the full load current, my poor mill does it with 16-in/lb running torque.
Conditioning or wetting the grain does not effect my mill, based on only two tests I ran (including current measurement).
What is hard on my mill is glassy (steely) grain, requires a lot more torque than mealy grain and won't start my mill with grain in the hopper.

Perfect!
Now slip tubing over the rod screwed to the rod on one side to produce an eccentric adjustment to vary the feed restriction.
That looks like 3/8" rod by the picture (guessing here), add 3/4" tubing with external arm to adjust and lock the setting.

What is the dimensions of your hopper, angles, height plus how many pounds will it hold?

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Carl no feed adjustment required, mill is happy
Hopper capacity close to 2 kg, 45° angle, not made for wet milling

Cheers,
ClaudiusB

shushikiary said:

Dry grain runs just fine, no issues what so ever, it's after the grain has been conditioned that's the issue. It might also be my impatience and running the grain while it's still a little damp after conditioning.

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The grain should be ready for milling soon after conditioning if it has been mixed well. I usually add the water and let the malt hydrate overnight in a covered bucket, but I've also milled it almost immediately (10-15 minute rest) with little noticeable difference.

ClaudiusB said:

You can use a fish scale and a string to do it.
Measure the motor current to see how close you are to the full load current, my poor mill does it with 16-in/lb running torque.

Carl no feed adjustment required, mill is happy
Hopper capacity close to 2 kg, 45° angle, not made for wet milling

Cheers,
ClaudiusB

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That's really amazingly low tq numbers.
Conditioned grain I bet requires 60 degree hopper angles preventing sticking plus grain flow interruptions to the rollers.
I have a spare Winsmith 40:1 worm box .86 HP 1750 input, 989 in/lb output this should break something.

Success! With the throttle bar in place I crushed 3 lbs of conditioned grain in about 45 seconds, 1/3 of that was wheat too, haha.

Thanks for posting your results, that will be a couple bottles of dark porter or stout sent to my island.

sjlammer said:

https://www.surpluscenter.com/item.asp?item=5-1098&catname=electric

Boom!

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Any one know how many watts this pulls?

Tim

P=I x E, watts = current x volts, 218.5 watts for that motor.

Anyone want to chime in re why I would use pulleys vs. a speed controller to dial-in my RPM's? Is it a matter of just having the motor running wide out and then gearing to the ideal speed or is there more to it? I mean, I'm looking at a 1750 RPM motor where a speed controller will cost roughly $25 vs. a set of pulleys and belts that will cost roughly twice that (unless I'm losing my mind).

I have not done anything like this befoer, but I plan to do so in the near future. My thinking is that if you have a speed controler it would be for a motor that has 200-300 rpm which seems to be a bit much depending on the mill being used. If a pully system is used the low rpms are constant. Maybe its just a toy to ramp up or down the rpm.

As for me I am looking for something that has under 200 rpms and high torqe (over 50 inch pounds). I dont really care about a speed controller. Also a love joy coupler is a nice option to have simply to reduce bearing wear on the mill.

I recently bought a high torque drill and for now it seems to work, although I really need 2 hands to control it. One for the grain mill (it seems to want to tip over at low rpms) and the other for the drill. A nice motor hook up is a nice way to go.

Torque. Remember that when you put a smaller pulley on the motor and a larger one on the mill it multiplies your torque.

So if you have a 50 inch lbs motor that runs at 300 RPM and you gear it down so the mill is running at 100 RPM you just trippled the torque the mill sees.

I've found that for my mill direct drive when doing malt conditioning required me to get a 115 inch lbs motor.

wow -necropost!

I'm not at home to check torque specs, but my gear motor runs a very slow 62 RPM - and it would crush gravel. I load up the hopper and walk away.

Hang Glider said:

wow -necropost!

I'm not at home to check torque specs, but my gear motor runs a very slow 62 RPM - and it would crush gravel. I load up the hopper and walk away.

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what motor are you using?

Tim

its a Bodine gearmotor, 130VDC from eBay - had to build a converter to AC, though.

looks like this one but I paid less than a tenth of that list price.

130VDC converts to 90VAC - so there was a bit of studying...

Hang Glider said:

its a Bodine gearmotor, 90VDC from eBay - had to build a converter to AC, though.

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RPM? Torque?

This is my motor 120 rpm at 150 inch lbs

its a monster, but it cost a pretty penny

This is mine. 90rpm. Works great.

johns said:

its a monster, but it cost a pretty penny

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Nope, $25 on e-bay and $40 for the control. If your not worried about speed I have a Dayton model 4Z130B 1/8HP 90Volt DC 22rpm at 280 in lbs of torque leftover that I was going to use to stir the mash. $30+ shipping

Does the desired grain size and rpm of the motor has a relation.

I just bought a cereal killer mill. Was going to use my drill. What’s best way of figuring out RPMs?

I don't know because my wife is milling the grain manually

I use an ancient GE fixed speed gearmotor that runs at 180rpm.
Short of using a tachometer I'm not sure how one would measure RPMs on a variable drill...

Cheers!

I run mine at 175rpm with a servo motor and controller. I am about to change it very easily in 5-10 rpm increments.

Here is a picture of my setup during the build.

old DC gearmotor makes for a speedy 62 rpm for mine - but y'know, I dump the grain in and go wash something...no big deal

1. K

   Seabee John said:

   I just was gifted a 5 HP 3450 RPM motor. I've got a 2" Drive Pulley connected to a 8" Driven pully on a mandrel, which I'll attach to the barley crusher via coupling. The resulting rpm is 862.5 or a .25 reduction

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Seabee John said:

How fast is too fast? I was hoping to keep with the 8", but if I need to, I'll start looking for a 10 or 12"

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I set mine at 200 rpm. Too fast and you shred the husks and create a lot of flour. Also, there are a couple old threads on homebrewtalk that cover this topic (mill RPM ????? and another about where to source pulleys for grain Mills). However, the motor you have has too many RPMs. Unfortunately you need a different motor.

You need to do the math for the size pulley your going to need. My speed is about 172 rpm. You will be wanting to get the smallest motor pulley you can. If I recall correctly, I had a 3/4 od going to the pulley which I think was 14, 15, or 16 inch. Can't remember exactly. I do know it was still spinning faster than optimal ...until I put a 10 to 1 reducing gear box as my mill drive. If you have a 3425 motor spin, you will have a monstrous pulley driving your crush roller.


Laughing at myself for answering a 9 yr old post. Don't know how I missed that....actually I do... 11.5 abv quad and distractions from the mrs.

SDMBREW said:

I affixed an old belt driven variable speed drill press to run my malt mill. I found running 500 - 600 rpm sufficient. I have run it up to 1700rpm and the quality of the crush was the same the only fear I have is prematurely ruining the bronze bushings.

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500-600 RPM is very high for milling barley and if you see no difference between that speed and 1700 RPM maybe the speed you are using is giving you an inferior crush.

Wow. Gotta believe there's a hella lot of dust created at those speeds...

i don't even know what rpm i run mine at, just have a variable speed lock drill....i set it at what ever seems 'right'.....i think it's 600-700 full speed, and i run it at half that....

Put a magnet on you shaft and get a free android app magnetic counter to measure RPM

There are also strobe light based phone apps that can help determine RPMs...

Cheers!