MM-3 Jamming Up

I've finally got around to building a mount for my MM-3 and am having some serious jamming problems. The mill is mounted under a piece of plywood with a hole cut above the rollers as per the specs that were included with the mill (1" x 5-6" iirc). The adjustment screws had come loose in shipment so I'm not at the factory gap getting, but I've played around from fairly narrow to the absolute max setting and the top idler continues to get jammed and stop pulling in grain. The driven roller will continue to spin but the grain just kinda sits on top of the feed point bouncing around and not going down through the mill.

Has anyone run into an issue like this? Any ideas on how to get this monster up and running. It's already killed my hopes of brewing today.

nicknunns said:

I've finally got around to building a mount for my MM-3 and am having some serious jamming problems. The mill is mounted under a piece of plywood with a hole cut above the rollers as per the specs that were included with the mill (1" x 5-6" iirc). The adjustment screws had come loose in shipment so I'm not at the factory gap getting, but I've played around from fairly narrow to the absolute max setting and the top idler continues to get jammed and stop pulling in grain. The driven roller will continue to spin but the grain just kinda sits on top of the feed point bouncing around and not going down through the mill.

Has anyone run into an issue like this? Any ideas on how to get this monster up and running. It's already killed my hopes of brewing today.

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I also have a MM3-2, sounds like your having an alignment problem with the roller journals in their bushings causing problems as they have from 0.003" to 0.005" journal to bushing clearance. First I would polish the end journals to a better finish than the production run for less oillite bushing wear, clean everthing and oil lightly the oillite bushings.

After taking my mill apart I had my rollers case hardened as well the journals then repolished the journals to again almost a chrome finish. As another member did on his MM3-2 I also have the same material and need to finish it (spinal surgery stopped all progress the past 5 months). This was to also use 3/8" thick top and bottom aluminum plates to bolt the end plates together for a strong and solid the end plates and bushings for alighment. I will mill tapered slots top and bottom on these plates. At a good hardware store get four 0.010" thin nylon washers that are almost like fender washers and setup your mill with 0.002" roller end clearances with these washers. This to make it harder and almost prevent all dust, dirt and grain particles from past the roller ends and into the bushings and journals causing more wear hence a longer mill life. This is what I started with on my mill.
Oh make the base 3/8" plate longer so that you can mount the mill on your table or what you have planned for a base below plus use a coupling drive like a LoveJoy (brand name) preventing unneeded extra side loading on the drive bushing vs a pulley drive. Again this for a long and trouble free mills life. JMO's as this was not a cheap mill I want it to live a long time.
I posted before in the past about adding a short piece of brass 5/16" long with a ball radius end matching the adjusting knobs radius, this soft brass on stainless bites better than the steel thumb screw against the stainless plus eliminated the turning thumb screw from turning the adjusting knob when tightening up and locking the knob adjustment tight. No need to use pliers as per instructions just finger tight as well the thumb screw and brass are a rotating point preventing the knob from rotating out of clearance.
Hope this helps. Best of luck.

I just received by MM3-2.0 mill last week and finally got it all assembled with a 12 inch pulley and 1/3 HP 1725 rpm motor (1.5 inch pulley on the motor). I have a thin plexiglass window on the "out" side of the mill. I can observe unmilled grain setting on top and not engaging the 3rd roller unless the gap is set at or below 0.038. As the directions indicate I used oversized holes in the top and bottom for the mill mounts. I can freely turn and even spin both nondriven rollers so there is not a binding or out of alignment issue. I had to "install" a larger flat on the shaft to successfully mount the 12 inch pulley.

The main reason I got the 2 inch rollers was to avoid the problem of grain not engainging the nondriven rollers. Is the 2.0 inch version not as tested and worse than the MM3 1.5 inch mill?

I find it interesting that the recommended setting of 0.045 will not turn my 3rd roller. However, in my opionion the 0.038 gap is too coarse. I have used a Corona grain mill for 10 years and typically use a finer crush.

I have not reported any observations to Fred yet since it is the weekend. I have spent a lot of the last few days just getting the mill ready for use and expected it to engage better. Since my motor is 1/3 hp I have to start the mill before adding the grain. This is not a problem.

At a 12:1 ratio reduction that 1/3 hp motor should kick butt, that motor have a starting capacitor on it rated for fan or a small compressor motor duty? That a low starting torque motor?
I have not completed my mill build project it's on standby while on the mend.
With a couple different worm drive handicap rail stair climber motor with gearbox as a single unit with 565 to 1,430 inch/lbs torque, the mills shaft will shear off first. Strange to hear that wider gaps kick back more grain than smaller gaps plus those rollers have rather sharp knurling that should pull in the grain. The larger 2" rollers have a lot less angle of attack between them than a 1 1/2" roller mill.

I have had mine for about 18 months and experience this problem from time to time. It usually happens when I don't blow out the flour after I mill. My mill is mounted under the lid of a bucket. I find if you roll the rollers by hand back and forth and blow out the four at the same time it stops the problem. You can do this after milling or before the next batch. I also found it very useful to loctite my set screws because they will loosen and change your gap causing your efficiency to take sudden shifts. Hope this helps. Derek

BrewBeemer,
My motor is a capicitor start motor and I expected it to have enough power to start the mill with grain in the hopper. It seems to work fine by prestarting the mill and then adding grain at 0.038 or below. When will you get your mill up and running I am anxious to hear how it works?

Derek,
I will use my air compressor and see if that helps but I can reach in and easily spin both of the nondriven rollers (when the motor is unplugged of course). Is your mill the MM3-1.5 inch or 2.0? Does your mill engage at the larger gap settings as easily as the finer settings? I assume that using loctite on the set screws makes the mill no longer adjustable. I may take Brewbeemers advice here and go with brass or the set screws with rubber ends.

What setting do most of you 3-roller guys use anyway?

I'm kind of surprised some of you are seeing better results (in your ability to grind) when the gap is set smaller. I seem to be getting grain stuck in between the two idler rollers.
I only have some of the wire-style gap gauges intended for spark plug adjustments. I'm going to pick up the blade style when I can and see if I can't get it properly set with those.
My instructions have run off on me. Can someone remind me which gap you are supposed to be measuring on the MM3? IIRC it's the gap between the driven roller and the bottom idler. Is that correct?

Yes, It is the gap between the driven and bottom roller.

Labrat said:

BrewBeemer,
My motor is a capicitor start motor and I expected it to have enough power to start the mill with grain in the hopper. It seems to work fine by prestarting the mill and then adding grain at 0.038 or below. When will you get your mill up and running I am anxious to hear how it works?

Derek,
I will use my air compressor and see if that helps but I can reach in and easily spin both of the nondriven rollers (when the motor is unplugged of course). Is your mill the MM3-1.5 inch or 2.0? Does your mill engage at the larger gap settings as easily as the finer settings? I assume that using loctite on the set screws makes the mill no longer adjustable. I may take Brewbeemers advice here and go with brass or the set screws with rubber ends.

What setting do most of you 3-roller guys use anyway?

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I would not use the air compressor as this will only force dust, dirt and grain dust deeper into your bushings and journals increasing your wear.
This is why I replied about keeping solid end frames and tight end clearances with thin nylon washers 0.010" thick between the end plates and rollers with a tight 0.002" end clearance. We have used a small 2" el cheapo nylon paint brush to clean out the mill.

nicknunns said:

I'm kind of surprised some of you are seeing better results (in your ability to grind) when the gap is set smaller. I seem to be getting grain stuck in between the two idler rollers.
I only have some of the wire-style gap gauges intended for spark plug adjustments. I'm going to pick up the blade style when I can and see if I can't get it properly set with those.
My instructions have run off on me. Can someone remind me which gap you are supposed to be measuring on the MM3? IIRC it's the gap between the driven roller and the bottom idler. Is that correct?

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With a wire gauge your reading between the bottom of the knurling of each roller and way off in the gap clearance. Get a feeler gauge or brass stock at the desired clearances, cut and attach the strips near your mill.

I went home at lunch and took Derek's advice about blowing air to clean out any residues (this is before I saw your latest post BrewBeemer). I then set the gap to 0.045 started the mill and added some grain. The 3rd roller took a second to engage and then began to shoot out the ground barley (pilsner malt)!

I have since reduced the gap to 0.035 which looks a little more like what I will probably use on the next batch. I will probably take BrewBeemers advice and look into getting the thin washers. If I understand you correctly the plastic washers should be slightly larger than 2 inches and 0.010 thick.

Although I have had no trouble yet with the set screws vibrating loose I may look into the brass (BrewBeemer) of rubber tipped set screws that someone has already posted about. Does anybody have part numbers (McMaster) for these set screws?

I usually set my gap at 42. I find if I go less I will get an occasional stuck sparge. I usually hit 75% with this crush in my system. If you use loctite get the medium not permanent. Then you can change your gap if you wish. Mine usually slipped after running malted wheat through. It is a 1.5 inch roller mill. Derek

Labrat said:

I went home at lunch and took Derek's advice about blowing air to clean out any residues (this is before I saw your latest post BrewBeemer). I then set the gap to 0.045 started the mill and added some grain. The 3rd roller took a second to engage and then began to shoot out the ground barley (pilsner malt)!

I have since reduced the gap to 0.035 which looks a little more like what I will probably use on the next batch. I will probably take BrewBeemers advice and look into getting the thin washers. If I understand you correctly the plastic washers should be slightly larger than 2 inches and 0.010 thick.

Although I have had no trouble yet with the set screws vibrating loose I may look into the brass (BrewBeemer) of rubber tipped set screws that someone has already posted about. Does anybody have part numbers (McMaster) for these set screws?

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I have seen nylon tipped set screws, my thinking nylon is almost waxy and will slip all the more. Copper is great but too soft I already went that route hence yellow brass slugs with a matching radius of the knobs radius.
My hardware store this year changed supplies of all their screws, nuts, washers you name it to Servolite (sp). They now have nylon washers at 0.015" thickness, 0.375" ID x 0.942" OD. This at Tru-Value and Ace Hardware in my small town. With 2" diameter rollers the washers maximum diameter should be no larger than the chamfered ends at the rollers around 1 7/8" maximum OD.
Next time apart I will go to Derlin plastic that is more slippery than nylon and use the gasket punch set for the ID with thin tubing sharpened on the lathe for the OD punch. This at 0.008" to 0.010" thickness or what my supplier will get me. Livermore Radiation Lab "G job" material.
MM is a great mill just need to add a little extra TLC to 'em in set up for a longer life. I want to protect my $246 investment and have it operate as much as their on line site advertisement states.

I just measured my fixed gap and it came out to be about .050". From MBH's site they say the fixed gap should be about .060". Obviously not the biggest difference, but a difference nonetheless.

I picked up some nylon washers from Ace but I'm going to have to alter the mount in order to accommodate them. The only ones they had were .062" thickness. Think this will pose a problem?

I think 0.060 seems pretty thick for the washers. Maybe you should reduce the gap a little bit and see if the 3rd roller engages. After blowing compressed air around mine it works at a gap of 0.045. I think 0.045 is too coarse even though I could not find a completely intact kernel. Good Luck.

A little more info:

As much as I play around with the gap, there are grains that are just kinda hanging out in the center of all three rollers.
From a completely fresh start, I start my drill up and it pulls a little grain in. after the first half-handful gets sucked in, the drive roller will continue to spin but no more grain will get pulled down between the top two rollers. I take the drill off and spin the bottom roller by hand and a bunch of grain comes out between the drive roller and the bottom roller. It appears everything's getting kinda stuck in the void between the three rollers.

nicknunns said:

I just measured my fixed gap and it came out to be about .050". From MBH's site they say the fixed gap should be about .060". Obviously not the biggest difference, but a difference nonetheless.

I picked up some nylon washers from Ace but I'm going to have to alter the mount in order to accommodate them. The only ones they had were .062" thickness. Think this will pose a problem?

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Your talking 1/16" or damn near 0.0625" the rollers are moving end plate to end plate exposing the journals to all that dust, dirt and grain particles then going back into the bushing again pulling in this dirt into the bushings. No those 0.062" nylon washers are too thick allowing for less journal to bushing contact not alone allowing grain to pass between the end plates and the rollers vs going between the rollers and cracked. That "fixed gap should be about 0.060" " is crazy, hell run grease in your car engine without big end rod bearing inserts that's how I rate that wide measurement. To rely on the narrow ends of the bushings with a radius as a contact area which is rather small to keep the rollers away from the end frames is weak at best and will wear away plus that much clearance allowing dirt to enter and wear on the small bushing contact area all the faster on that radius plus the roller journals to wear away against faster. All my bushings were all over the place in stick out from 0.007" to 0.097" holding the rollers away from the end frame to rollers hence why I set all bushings flush with the end plates then run thin 0.010" nylon washers with the tight 0.002" end clearance. No more roller to end plate scars and wear marks that came delivered this way from brand new "Passed Inspection and Tested at MM" as well the tight clearances that keep the bushings running cleaner on the journals preventing wear on them also. The oillite bushings will hold the grit allowing the journals to wear away. Why do you add oil to a knife sharpening stone sharpening a knife besides clearing away the metal particles? The case hardening was my added idea as I had a friends business do it for me for free. The extra items I have done would cost Fred time and labor that would eat into his profits, "KISS" system and sell many of 'em.