Motorized Monster Mill MM3 Pro Build

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mfabe

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Hello,

I just finished motorizing my Monster Mill MM3 and thought I would share a few pics and a build list in case anyone wanted to emulate or improve upon my setup...





I chose to mount the mill on a service cart because we only have a one car garage, and that is stuffed full of tools and other stuff. So instead we have a storage area just inside our garage, and its easy to wheel the mill outside or in the garage to process the grain. Furthermore, in light of the fact that I was going to store it inside, I wanted something a bit les conspicuous than a bright red service cart, so I did a once over with gloss white enamel so its easy to wipe down. The only other modifications I made to the cart was inverting the top shelf so it created a flat surface to mount the mill and motor.

The monster mill base was great because it acted as a jig to drill the mounting holes and make a cutout for the grain to pass through. After it was mounted it also acted as a nice stiffener.

I read that a lot of other people have gotten by with a 1/2 hp with an MM3, but the Monster mill website recommended a 1 hp... So I opted to split the difference and get a 3/4 hp capacitor start motor. I chose the "tool replacement" enclosed version because it is made to standup to saw dust, so I figured grain dust and other junk wont cause it to start having problems. I mounted the motor on a type 56 base so that I could easily adjust the tension of the v belt.

To keep the budget somewhat under control I went with sheaves instead of a gear reducer, but I opted to go with the tool replacement grade Martin Sheaves so it would be a smooth as possible. I've seen other cast iron sheaves, and they look like junk. Cheap casting, poor machining, and just eyeballing them they appear out-of-round. The only problem is that Amazon only had the Martin sheaves up to 9.25" in stock with a 1/2" bore. So the mill will turn at approx. 240-250 rpm, which is a little on the high side, but should work ok. I used my dremel to put a small indentation in the shaft of the MM3 to accommodate the lock nut. For the smaller sheave, the smallest I could find was 1.75" OD, which already has a key way for the motor's shaft.

Other misc. stuff I used included a 14 AWG tool replacement cord, rated for 15 amps (the motor draws 10.3 amps on 120v). A magnetic start stop button, a 40" 4L profile v-belt, and wire glands, hardware, etc to finish it off. Here is a complete list, most everything can be purchased off Amazon:

Monster Mill MM3 Pro
Service Cart
9.25" Sheave
1.75" Sheave
Type 56 Motor Mount
3/4 HP Grizzly Motor
Switch
Belt
Cord

My general thoughts about the operation of the mill and motor are very positive. Its spins extremely smooth, with absolutely NO vibration or other issues. In fact I'm really surprised at how little tension the belt needs to process even rye and wheat. The startup of the 3/4hp motor is strong, and handles a full hopper from a complete stop without an issue.

After a good amount of use, I'm almost convinced that most users could even get by with a 1/2hp without any issues at all. One other obvious observation is that the cart isn't the best quality, but it does the job like champ. I cut a piece of plywood to sit across the lower shelf, which helps push my 6.5 gallon bucket up under the cutout in the cart. This keeps the grain contained really well. All-in-all I'm extremely happy with the MM3 pro, I don't know if I would change that much about my build, other than maybe getting a smaller motor and building a belt guard...
 
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outside92129

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Nice clean build! Looks like you have a nice brewing area too!

I'll second the vote on the belt guard, if i didn't have lil'tikes who like to mess with stuff i could probably get away with exposed sheaves on mine. But seeing as they're my retirement plan i went with a gear reducer (on a 1/2hp, works great)
 

BungBrewing

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... I just finished motorizing my Monster Mill MM3 and thought I would share a few pics and a build list in case anyone wanted to emulate or improve upon my setup...
I am considering the Monster MM3-Pro mill also. After a couple more months of use since your original post, what is you overall impression of the mill? (Still happy with it? - There haven't been a lot comments on this mill in here.) Do the bushings seem to be wearing OK with the weight of the cast iron sheave on it?

Are you sure you are running around 240-250 rpm? With a 4L belt, they typically run closer to the true pulley size ratio and I would have guessed you'd be closer to the neighborhood of ~300 rpm with a 1725rpm motor and those pulley sizes. I already have a cart and a 1/2 hp motor (TEFC Leeson - 840 rpm) I'm going to use - although I'm planning on turning it just around 180-200 rpm.
 
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mfabe

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I absolutely love the MM3 mill after using it the past few months or so, it really is a well made product!... and you might be correct that it turns in the high 200s or low 300 rpm range.

I have taken it apart a few times over the last few months to tune the crush a bit finer. Just lately I have really dialed it in perfectly and have been getting great efficiency and lautering performance, with no stuck sparges. I actually brew on a Blichmann breweasy, and thats one of the key elements of that system is good lautering. A stuck spare results in a complete disaster of a brew day!

I haven't noticed any abnormal wear on the bearings, even when I had it completely taken apart. But I'm only brewing about 1-2 times a month with about 30-35 lbs of grain per brew, so its not like its in a home-brew shop or something. In fact, it takes very little tension on the belt to run the mill effectively. If I squeeze the belt between the two sheaves, the belt actually lifts off the small sheave, so that gives you and idea of how little tension there is. You really don't need to have it cranked down for everything to function well, and just in case something locks up it won't tear apart the entire build! The belt has room to slip...

I find the larger cast iron sheaves provide good weight and reciprocating mass to smooth out any vibrations over a few cast aluminum csheaves I've seen. It really is the smoothest running mill I've ever experienced... Let me know if you have any other specific questions about it! Cheers
 
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I am considering the Monster MM3-Pro mill also. After a couple more months of use since your original post, what is you overall impression of the mill? (Still happy with it? - There haven't been a lot comments on this mill in here.) Do the bushings seem to be wearing OK with the weight of the cast iron sheave on it?



Are you sure you are running around 240-250 rpm? With a 4L belt, they typically run closer to the true pulley size ratio and I would have guessed you'd be closer to the neighborhood of ~300 rpm with a 1725rpm motor and those pulley sizes. I already have a cart and a 1/2 hp motor (TEFC Leeson - 840 rpm) I'm going to use - although I'm planning on turning it just around 180-200 rpm.

I've had my 3 roller MM for about 9 months. I did a gear reduction direct drive setup that operates the mill @ 180 RPM.
The mill has been excellent and dependable. Great crush, too.
View attachment ImageUploadedByHome Brew1428183167.866427.jpgView attachment ImageUploadedByHome Brew1428183264.858137.jpg
 

BungBrewing

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I haven't noticed any abnormal wear on the bearings, even when I had it completely taken apart. But I'm only brewing about 1-2 times a month with about 30-35 lbs of grain per brew, so its not like its in a home-brew shop or something..........

......I find the larger cast iron sheaves provide good weight and reciprocating mass to smooth out any vibrations over a few cast aluminum sheaves I've seen. It really is the smoothest running mill I've ever experienced.......
Thanks, that sounds great... I was originally thinking about aluminum sheaves, but I think I'll copy you and go with the cast iron sheaves... And since I'll be using a 840 rpm motor, I can go with a smaller sheave on the mill. It will still have some mass to it, but an AK59 or AK61 will weigh roughly half what your AK94 weighs... And if the bushing ever wears out, I'm sure I will be able to replace it...

Edit: Wow, I was looking the last couple of days at sheaves and the AK59 was was in the mid $30 range on Amazon, just looked a few minutes ago and it had dropped to $10.09! I ordered it (with Prime) and the total was $10.90 with tax. When I clicked on the same sheave again, the price jumped back up to $38.91! I can pair it with an AK15 on my motor for a calculated speed of 198 rpm (with a 4L belt).
 
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MultumInParvo

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This is great! I have always bought grain premilled and never had the space to crush my own grains. We just bought a new place so I might be stealing your work shortly!
 

theonetrueruss

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nice build I've been looking at what I want to build along this line and I think this is the way I will go. My old mill is getting worn and.. ok its and excuse. I want a motorized mill on a cart.
 

theonetrueruss

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hey- I have a question on the motor power. You say that you would go with a smaller motor if you redid it. Is this just a cost thing or is there another reason for a smaller motor?
 
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mfabe

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hey- I have a question on the motor power. You say that you would go with a smaller motor if you redid it. Is this just a cost thing or is there another reason for a smaller motor?
If the cost difference between 1/2 and 3/4 HP was pretty low I would stay with the 3/4. However, if you had a access to a 1/2 HP at say half the cost of the 3/4 I would go that route!

Overall I'm EXTREMELY pleased with the mill and the motor, and I couldn't even begin to comment on whether or not a 1/2 HP motor would have even held up. However, what I can say is that the 3/4 HP motor doesn't struggle one bit even with running 2-3 50 lb bags through the mill in one sitting. It could go all day...
 

jammin

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I had terrible results with 2 different sets of shieves and pulleys.

I would strongly encourage folks to steer clear of belt driven rigs and go straight for a gear reducer. Much more robust and no chance of slipping. It's just a much more sound rig
 
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mfabe

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Its been a year and I haven't had a single problem with the belt/sheaves, but that is likely the result of being able to dial in the tension. If someone fixed the tension setting I could see that being a problem. Plus I didn't go with those crappy cast aluminum sheaves...

Everything is essentially "tool grade", and I've worked on a lot of table saws, air compressors, and other shop tools that used sheaves and never had a problem, so I guess I just have faith in them.

I agree gear reducers are great, just costly at the same time.
 

jammin

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^depending on your setup, a belt drive can work great.

When it comes to high torque requirements though, a gear reducer is the correct answer. Honestly, I'm surprised you're able to get a belt drive system to work with the MM3, 2.0 well. Even with a low ratios I had trouble slipping and it was a IMPOSSIBLE to start a full load from a stop
 

theonetrueruss

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Do you know of a gearbox that would work well with say that Grizzly motor? OR another motor gearbox combo? I pushed the button on the MM# 2.0 and am now looking to finalize my motorization setup. I considered the direct drive but just haven't been able to find the parts whereas the parts for the pulley system are reasonably available. I can't seem to find an inline gear reducer.
 

theonetrueruss

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I committed and ordered my mill and other parts. Mill got here quick-damn that think is heavy. Makes my old barley crusher feel like junk. I decided to go with the pulley system and a 1hp motor. Got it for just a little more than the 3/4hp. I figure with that much power getting stuck and starting should not be a problem if I have my tension correct. Gonna build a cart from wood. Will post when done. Should be a couple weeks. Thanks!
 

theonetrueruss

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Ok.. I got my sheaves. Sometimes the smallest things in these projects give me trouble. I can't seem to figure what tool to use to tighten down the large pulley. The small one seems to take a hex wrench but for the life of me I cant find the right size for the big one. What on earth am I missing?
 

theonetrueruss

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ok.. worked out which hex wrench to use.. but the darn set screw doesn't seem to come down far enough to contact the shaft of the mill. It gets stuck right before it comes through the hole... Do I just need to apply a lot of torque or perhaps is the part possibly defective? Is there some other part I am missing? (using the large sheave linked to in the parts list)

update- nearly broke my hex wrench with applying torque but the set screw finally pushed through. I do think the tap for the set screw was poorly done in manufacturing but I seem to be past that now.
 
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mfabe

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Looking good, Yah I remember my set-screw needed some motivation to get seated in the right spot. Glad you got it worked out!
 

theonetrueruss

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got mine up and running this weekend... test run with 2 lbs of grain in video. I am somewhat convinced that I would have failed without the motor mount. It allows getting the tension on the belt right. Next weekend will be the first brew day with grain milled in it. Took me a day longer to build than I anticipated- kept needing to get little bits like connectors, different wire etc. Runs like a champ though.

https://www.facebook.com/russellbcopeland/videos/10153858754502299/
 

ubermick

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Pfft. Given your other build threads, I'm frankly disgusted this isn't on a stainless cart with an aerospace-TIG welded hopper, and a custom built motor. Hmph.

;) Great build!
 
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mfabe

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Pfft. Given your other build threads, I'm frankly disgusted this isn't on a stainless cart with an aerospace-TIG welded hopper, and a custom built motor. Hmph.

;) Great build!
Oh you mean like this...



LOL Here is my latest build V2.0. To be honest I still like sheaves because it just "felt" smoother than the gear motor, but alot safer this way.

For those inquiring minds, the mill is spaced by a 1/2" thick plate of 6061 aluminum that I machined/surfaced to a custom thickness on my mini mill.

Other than that, its just a standard stainless table with holes cut in it.
 

tezcatlipoca

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Oh you mean like this...



LOL Here is my latest build V2.0. To be honest I still like sheaves because it just "felt" smoother than the gear motor, but alot safer this way.

For those inquiring minds, the mill is spaced by a 1/2" thick plate of 6061 aluminum that I machined/surfaced to a custom thickness on my mini mill.

Other than that, its just a standard stainless table with holes cut in it.
Holy cow Batman!!!! I loved v1.0. Little did I know I was looking at a rough prototype!!

I'll probably be doing something similar to this in the spring.
 

SanPancho

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Oh you mean like this...



LOL Here is my latest build V2.0.
you got a V2 parts list, or info on the motor you're running on that one? is it geared down out of the box or you had to add gearing?

and pretty lookin shaft couplers, too.
 

olie

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Oh you mean like this... [snip]
I have a setup like that (not as nice as yours), but the gasket is wearing out on that coupling between the motor and the mill shaft. It has a fancy name (after the inventor? Like "a Murphy coupler" or similar?) and I can't remember what it's called, so I can't search to find replacement plastic/rubber gasket. Any ideas?

Thanks!
~Ted

EDIT/UPDATE: The thing I have/need parts for is called a "jaw" or "spider" coupling (not after the inventor. Maybe not that fancy ;) ), though searching for `shaft coupling` gets you lots of variations.

McMaster & others have whole units or parts (I just need the rubber insert).

P.S. The name that I thought might be the inventor was "Lovejoy coupler", but that might be a style of jaw coupler, or maybe a manufacturer name. Anyway, that's what I got on Amazon, all those years back.
 
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