Need help setting gap on Monster Mill

I have a 3 three roller monster mill. I have it mounted and motorized, but I can't figure out a good way to set the gap.

I know the top rollers are fixed. I have a feeler gauge, but I have 2 questions:

1) Which rollers do put the feeler gauge between? The motorized roller and the bottom roller? Or the non-motorized roller and the bottom roller.

2) How do you do this? With the side plates, hopper and mounted to the table it seems impossible. Even unmounted it seems very awkward to say the least.

Are you supposed to remove the hopper and the side plates to set the gap with a feeler gauge? This seems like a lot of work just to adjust the gap, no?



Any help is greatly appreciated. I'm stumped.

I check then gap between the drive roller and the third roller. I make sure to set it on a level surface. I remove the mounting plate and the hopper(yea it sucks). Not sure if this is correct or not. Their website only talks about setting the gap on the 2 roller mill.

With the way you have it set, can you go from underneath?

gnef said:

With the way you have it set, can you go from underneath?

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Not really. I tried, but it's pretty hard if you want to be accurate. I can't reliably get the feeler gauge between the mechanized roller and the third roller, let alone adjust the knob. It's a 3 roller mill so you'd need like a 90 degree feeler gauge, and even then...

I'm a little annoyed with Monster Mills on this one. They provided very little in the way of documentation and now I find out it's a lot of work to adjust this one. I wasn't anticipating that. Then again, I'm rarely as patient as I should be when shopping. I read quite a few threads, though and no one mentioned this issue. Oh, well. I'm off to disassemble the mill to adjust it.

I just hope I can get a mill setting that works. Changing it is clearly a PITA!

Some folks have replaced the side thumb screws with bigger/knob bolts. I had a jam this weekend and nothing sucked more than having to look for the right tools in the middle of a brew day. I'm in the process of replacing all the key disassemble bolts/screws with wing screws and other bits that don't require tools.

Bolt/screw sizes:
hoppers are 8-32 x 3/8,
mill bolts are 1/4-20 x 1 1/4
gap lock bolts are 1/4-20 x 2

...and after adjusting the gap, should you find that the crush still isn't quite where you want it, you get to go through all that hassle again and often more than once. IMO, the lack of on-the-fly adjustment is a major design deficiency with these mills.

Catt22 said:

...and after adjusting the gap, should you find that the crush still isn't quite where you want it, you get to go through all that hassle again and often more than once. IMO, the lack of on-the-fly adjustment is a major design deficiency with these mills.

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I think the idea is that if you set it for .040 you can adjust it a bit without taking it all apart, but this is a good point.

I set my gap for 0.036. I had some old grain laying around and I gave it go. The mill jams anytime there is more than a tiny bit of grain in the hopper. Doesn't matter whether I turn it on first or not.

I'm wondering if my 40 in/lb gear motor can handle the job. Reversing it and then going forward again gets it working, but it quickly jams if there's more than an inch of grain in the hopper.

So... do I take it apart again and try to make sure everything is square? Make the gap slightly larger? Start thinking about a more powerful motor?

Geeze... need a homebrew. Any advice is appreciated.

I make a line on the knob with a sharpie, then adjust the gap to a few gaps and mark the mill. That way I can adjust it without taking it apart. Not sure the gap is the feeding issue. The top rollers are a fixed gap.

Dgonza9 said:

I think the idea is that if you set it for .040 you can adjust it a bit without taking it all apart, but this is a good point.

I set my gap for 0.036. I had some old grain laying around and I gave it go. The mill jams anytime there is more than a tiny bit of grain in the hopper. Doesn't matter whether I turn it on first or not.

I'm wondering if my 40 in/lb gear motor can handle the job. Reversing it and then going forward again gets it working, but it quickly jams if there's more than an inch of grain in the hopper.

So... do I take it apart again and try to make sure everything is square? Make the gap slightly larger? Start thinking about a more powerful motor?

Geeze... need a homebrew. Any advice is appreciated.

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IIRC, the general recommendations for minimum torque was approximately 50 in-lbs, but this is only a ball park number and it will be different for various mill designs.

You can mitigate the problem by restricting the flow of the grain onto the rollers. Visualize the grain entering the mill through a relatively narrow port. It will spread out across the rollers as it gets pulled in. The grain feed rate and roller rpm will affect how wide the grain spreads out. IOW, you can slow the milling rate by narrowing the feed chute so the rollers are not covered completely from end to end. An adjustable feed chute in the bottom of the hopper would be ideal. Something like a simple sliding plate would do it. There are some other threads that discuss restricting the feed rate.

hmmmm, I think I might just go with a bigger motor. I have a blower motor sitting around. Maybe I can get a gear reducer. I don't want to use sheaves.

Dgonza9 said:

hmmmm, I think I might just go with a bigger motor. I have a blower motor sitting around. Maybe I can get a gear reducer. I don't want to use sheaves.

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FYI, restricting the feed rate is nothing to be ashamed of. IIRC, some of the mills/hoppers are designed with this feature for exactly this reason. It would not be difficult to run a quick test. You could make a baffle out of a piece of cardboard to give it a try.

Catt22 said:

FYI, restricting the feed rate is nothing to be ashamed of. IIRC, some of the mills/hoppers are designed with this feature for exactly this reason. It would not be difficult to run a quick test. You could make a baffle out of a piece of cardboard to give it a try.

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I hear you. I just do 10 gallon batches and next up is a IIPA with a 30lb grain bill. Given the way my mill was jamming, I don't think I'd attempt it with my current motor.

I always try to research ahead of time, but it seems I can never stumble upon the right thread until I have the search terms for what the problem winds up being. Now that I look for "motor for mm3" I see that the rated torque on this motor is too low. 50-60 is minimum for the three roller mill.

Crap. I wonder what else I can use a motor for around the house?

Okay, I actually have an old blower motor. It's 1/4hp. 1725RPM. I had to calculate the amount of torque this will produce. I'll put the formula in here in case anyone needs it. I had to hunt around for a while.

Am I doing this right?

torque(T) = (5252 *HP) / RPM


T= (5252 * .25) / 173RPM (if I reduce with a 10:1 Gearbox)

T= 7.59 Foot/lbs

Converted to in/lbs (multiply by 12) = 91.08 in/lbs

Be a huge improvement, assuming I did that correctly.

milldoggy said:

I make a line on the knob with a sharpie, then adjust the gap to a few gaps and mark the mill. That way I can adjust it without taking it apart. Not sure the gap is the feeding issue. The top rollers are a fixed gap.

Click to expand...

I did it one time. I marked my knob with a sharpe and put marks from .040 to .025. I now use mine set @ .030 and is good for most all grains. Love the crush and I condition my grain too. Once you do this you won't have to go through it again.

Dog House Brew said:

I did it one time. I marked my knob with a sharpe and put marks from .040 to .025. I now use mine set @ .030 and is good for most all grains. Love the crush and I condition my grain too. Once you do this you won't have to go through it again.

Click to expand...

I'm trying to do this now but a 0.002 difference is so slight. Can you post a picture? I was thinking about using a punch to mark the gaps.

Had found this thread before buying the MM-03, I might not be stuck in the same predicament of having issues setting mill gap. With the (near)complete lack of documentation available I have taken to banging my brain housing against wall. Did your idea of a larger blower motor work Dgonza9? I might just go medieval and get the manual crank handle. Its one way to work out the frustration.

After using mine for a bit I thought I'd post when I came up with.

Since there is no way to put on or take off the hopper without removing the thumbscrews, I put short set screws to lock down the gap. Then I put the thumbscrews back in to keep them locked in. This allows me to remove the hopper without losing the gab setting.

Here is my gaping procedure:

Remove thumbscrews
Remove hopper
Loosen set screws
Gap mill at both ends
Tighten set screws
Install hopper
Install thumb screws


Right now I'm at 0.040" and have had great extraction (averaging 82%) and no stuck sparges, even with 40% wheat, although I did add rice hulls for insurance. After I get a few of the same recipes brewed I may drop it down to 0.038" and see how it affects things.


As for the motor, I'd wanted to have a geared pulley/lovejoy/motor permanent type setup but I started out with a Harbor Freight drill setup. It's worked well and not I'm not sure if I'll ever build a station. This one breaks down easier and now I have a nice mortar mixer as well.

Here is the one I got:

Chicago Electric Power Tools Professional - item#93632
http://www.harborfreight.com/1-2-half-inch-heavy-duty-spade-handle-drill-93632.html

It has nice torque and a speed control setting. I'll lock the trigger down and dial in the speed I need. There is a sweet spot were it feeds nice but isn't too slow it wants to bind. You can always find a 20% off coupon too so $35 for a "motor" setup isn't bad at all in my mind.

I use that drill. A trick to make holding it easier, get a board, I use a deck balaster, place it on top of the base to the left. Let the drill handle hit the board. Then you just to hold the board, wihich is 20 times easier than the drill.

milldoggy said:

I use that drill. A trick to make holding it easier, get a board, I use a deck balaster, place it on top of the base to the left. Let the drill handle hit the board. Then you just to hold the board, wihich is 20 times easier than the drill.

Click to expand...

I'm going to try that but clamp it to the base so I'm totally hands free. Thanks for the tip!

Just used that drill with my MM2.0 last week and it worked out great.

Bigscience said:

I'm going to try that but clamp it to the base so I'm totally hands free. Thanks for the tip!

Click to expand...

Yea, I was thinking about a bolt through the base with a large wing nut to hold down the board. Just have not got around to it.

i went all wing nuts and finger screw heads on my mm3-2, and have a 1/2 hp motor from ebay that ran $20. The gap size was set and it's working well for us. The mil still jams every other batch of grain, but we've figured out our process:

1) turn on
2) put in 1 cup of grain to prime the mill.
3a) if it jams, stop motor. Reach underneath and turn bottom roller to remove grain. Go back to step 1.
3b) if the mill starts milling properly *quickly* dump in the rest of the grain. If it chewed thru all the primer grain you have to go back to step 1.

One the mill gets going on grain it doesn't jam. Getting to that point can be a pain but it usually takes hold with 3-4 iterations. Ask me if i would do the same if i got to do it over : )

I have noticed the same PITA issues with our 3 roller MM. It doesn't like to play well with others and man for the price paid it should be more reliable.

Gap set to .35 motor set to 183rpms with pulleys. Getting 70% efficiency or just slightly under. Kinda disappointed in the efficiency, as I would like to be more like 73-75%. Was trying to decide if going down to .030 would do the trick.

My feed issues happen at the first two rollers, not the gapped setting. So it really makes me scrunch my brow since that setting is supposed to be .060 if I am not mistaken.

Hmm. I have never had a problem with any of my 3 Monster mills, one motorized, two manual. I switched from the barley crusher because it was the one that stopped crushing and would get jammed every couple turns. I'll have to keep my eyes on them. But with over five years on my oldest one I think I may be good. Maybe a decrease in QA?