Monster Mill Problems

[pbrosnan]

Hi all,

Been using my 2 roller MM for about 12 months (12 or so brews). All was fine up until last brew. I started up the motor and began to fill the hopper. I quickly noticed that the level of grain in the hopper wasn't dropping. After some investigation (i.e. taking off the hopper and sundry bits of my crappy carpentry) I found that the grain wasn't being pulled into the rollers.
With the motor running at normal rpms the grain just bounces around on the rollers, the non-powered roller doesn't turn at all although it will turn when pushed by hand so it's not obstructed or seized. The strange thing is I haven't changed anything, it started happening out of the blue. I've fallen back to my drill powered Marga which hasn't missed a beat in over 40 brews. The MM was a replacement for the Marga but after spending 2 hours this arvo fiddling with the gap and stripping the whole thing and still not getting anywhere I'm thinking I may be better off motorising the Marga.
Has anyone else had anything similar happen?

cheers

Patrick.

 

[warrenlw63]

Patrick

I have the same mill. Just sounds like a simple obstruction in the idle roller. Maybe pull the mill apart and clean and/or oil the bushings on the idle roller?

It's probably less of a problem than you think. If the idle roller is not spinning "very" freely then it won't work.

FWIW what's your gap set at?

Edit: I don't want to sound like I'm insulting your intelligence but is the powered roller spinning in the right direction? ie; towards the idle roller?

Warren -

 

[clatty]

Hi all,

Been using my 2 roller MM for about 12 months (12 or so brews). All was fine up until last brew. I started up the motor and began to fill the hopper. I quickly noticed that the level of grain in the hopper wasn't dropping. After some investigation (i.e. taking off the hopper and sundry bits of my crappy carpentry) I found that the grain wasn't being pulled into the rollers.
With the motor running at normal rpms the grain just bounces around on the rollers, the non-powered roller doesn't turn at all although it will turn when pushed by hand so it's not obstructed or seized. The strange thing is I haven't changed anything, it started happening out of the blue. I've fallen back to my drill powered Marga which hasn't missed a beat in over 40 brews. The MM was a replacement for the Marga but after spending 2 hours this arvo fiddling with the gap and stripping the whole thing and still not getting anywhere I'm thinking I may be better off motorising the Marga.
Has anyone else had anything similar happen?

cheers

Patrick.

Hey Patrick

I just motorised my MM3 and found that I had the mill sides too tightly screwed to the bench and the non-powered roller would not turn smoothly (i had to loosen the screws and tap the sides out with a rubber mallet, see pic). As Warren said there maybe something obstructing the roller as yours worked ok before... How freely does the non-powered roller move by hand? Good luck with it.

 

[pbrosnan]

Patrick

I have the same mill. Just sounds like a simple obstruction in the idle roller. Maybe pull the mill apart and clean and/or oil the bushings on the idle roller?

It's probably less of a problem than you think. If the idle roller is not spinning "very" freely then it won't work.

FWIW what's your gap set at?

Edit: I don't want to sound like I'm insulting your intelligence but is the powered roller spinning in the right direction? ie; towards the idle roller?

Warren -

Hi Warren,

Thanks for the reply. No need to worry about insults to intelligence and the powered roller is spinning the right way. I took the idle roller cams off and sprayed a bit of silicon lube in which didn't seem to make much difference. Do you know if the idle roller is sitting on a bearing? I'll continue to try and fix it via the idle roller then. Gap has varied a bit this arvo, I think it's at about 0.9mm ATM.

cheers

Patrick.

 

[pbrosnan]

Hey Patrick

I just motorised my MM3 and found that I had the mill sides too tightly screwed to the bench and the non-powered roller would not turn smoothly (i had to loosen the screws and tap the sides out with a rubber mallet, see pic). As Warren said there maybe something obstructing the roller as yours worked ok before... How freely does the non-powered roller move by hand? Good luck with it.

View attachment 28794

Hi Clatty,

It could spin more freely. If I give it a push it probably stops within a 2-3 seconds. I don't know what it was like before it stopped working. I hate wasting of grain trying to fix it.

 

[Zwickel]

Patrick, I had the same issue with mine.
After I had milled around 100kg of grain, the roller had lost its grip and the idle roller was still standing, no grain went through.
What Warren says, helps a little while, but in my case it came again and again and got really anoying.

In the end, I had only two chances, either way ditch the whole mill or synchronize the rollers.

I decided to go the second way.

What I did: just cut two cogwheels out of a piece metal sheet:



made a distance holder like that:



and mount it behind the rollers:





voil, the mill runs again, no more worries.

Cheers :icon_cheers:

 

[Vlad the Pale Aler]

I have an MM3 which I bitterly regret buying, like yours it fails to perform on occasion without any reason at all.
I stripped the thing down and cut a slot in the end of the idle roller with an angle grinder, I use this to "kickstart" the mill with a screwdriver when it stalls.
The knurl on the rollers seems too smooth to pull the grain in so I reduced the intake opening in the hopper which helps,( I would post some pics but its cold in the shed and this 80/- is too good to leave alone).

 

[pbrosnan]

Hi Zwickel,

Beautiful job but probably beyond my skills as a metal worker. I would be easier to motorise the Marga. It does sound like we have the same problem though. I was wondering if there was a way of re-roughing the roller surfaces to see if I could get it to grab the grain more positively.

 

[RobW]

I have the same mill and it's done that a couple of times recently.
I found it was one of the thumbscrews vibrating loose and opening up the gap a little.
If I tighten the thumbscrew it's OK for a while then slips again.
Probably needs a bolt or a screw instead of the thumbscrew so I can tighten it a little more.

 

[Zwickel]

...I would be easier to motorise the Marga. It does sound like we have the same problem though. I was wondering if there was a way of re-roughing the roller surfaces to see if I could get it to grab the grain more positively.

Patrick, my mill is motorized, that doesnt change the problem.
In the first time I could help myself by increasing the gap to 1.8mm and mill again a second time by setting the gap to 0.8mm
That worked well for a certain time, but then the problem started again.

I even changed the rollers three times, have the third set of rollers meanwhile. All of them showed the same issue.

I really have been close to sledgehammer the mill.

Fortunately, finally Ive found the solution, inspired by the Mashmaster Mill.

Cheers :icon_cheers:

 

[pbrosnan]

Hi all,

I'm surprised by the number of people reporting this behaviour. It appears without radical modification ala Zwickel that the unit exhibits poor performance after a reasonably small number of brews (in my case about 10 or 12)? I probably can't use your solution Vlad as the way I have it setup I don't have easy access to the rollers. I tighten the thumbscrews with a pair of pliers as I had the loosening problem so its not the gap slipping and anyway I tried a lot of different gaps and have seen very little change. This is a great disappointment as it was milling 6kg in about 3 minutes. The only problem I had prior to this was not enough torque from the motor and like you Vlad I added a choke to the hopper to slow down the feed.

 

[pbrosnan]

Patrick, my mill is motorized, that doesnt change the problem.
In the first time I could help myself by increasing the gap to 1.8mm and mill again a second time by setting the gap to 0.8mm
That worked well for a certain time, but then the problem started again.

I even changed the rollers three times, have the third set of rollers meanwhile. All of them showed the same issue.

I really have been close to sledgehammer the mill.

Fortunately, finally Ive found the solution, inspired by the Mashmaster Mill.

Cheers :icon_cheers:

Hi Zwickel

Did you get new rollers from the manufacturer or did you make them up? And just to be clear, you think the problem was with the knurling on the rollers and the mill having to rely on the knurling to turn the idle roller?

 

[Thirsty Boy]

Have you tried varying the speed of the mill? I know that if mills run too fast, they can bounce the grain around without pulling it in. Vlad also mentioned reducing your hopper opening. Reducing the flowrate of grain in also helps to smooth out feeding issues in mills.

Also, a bit of a wire brushing of the rollers might help - the knurling might have lost a little of its edge which was previously helping to drag the grain in -- worn off a little its no longer doing the job. A bit of a brush up might give it back a little bite.

Also, a low tech way to get an active #2 roller is to put an o'ring onto the driven roller that gets squashed up against the passive roller - this spins the passive roller, not with enough force to do anything much, it is still "crushing" the grain a passive roller, but it helps with dragging the grain into the mill.

I have the MM 2 and have yet to experience any issues -- but I tend to run my mill quite slowly (120-150 rpm or slower) -- I don't know if this is one of the reasons mine is still working well, if I have just been lucky so far, or if you guys have just been unlucky.

TB

 

[Online Brewing Supplies]

Hi Zwickel

Did you get new rollers from the manufacturer or did you make them up? And just to be clear, you think the problem was with the knurling on the rollers and the mill having to rely on the knurling to turn the idle roller?

I will post a solution to you by email/PM.Its a bit of work but doesn't involve any mechanical reworking.
GB

 

[kram]

I've done 35 or so batches with mine now, after about 25 it stopped pulling through. I think the gap just closed up a little; it made me get off my arse and finally build a proper stand and hopper for it. Put it back together, reset the gap and it's been going fine. Only once i've had to tap the idle roller to start it spinning to get the crush going.

 

[pbrosnan]

Have you tried varying the speed of the mill? I know that if mills run too fast, they can bounce the grain around without pulling it in. Vlad also mentioned reducing your hopper opening. Reducing the flowrate of grain in also helps to smooth out feeding issues in mills.

Also, a bit of a wire brushing of the rollers might help - the knurling might have lost a little of its edge which was previously helping to drag the grain in -- worn off a little its no longer doing the job. A bit of a brush up might give it back a little bite.

Also, a low tech way to get an active #2 roller is to put an o'ring onto the driven roller that gets squashed up against the passive roller - this spins the passive roller, not with enough force to do anything much, it is still "crushing" the grain a passive roller, but it helps with dragging the grain into the mill.

I have the MM 2 and have yet to experience any issues -- but I tend to run my mill quite slowly (120-150 rpm or slower) -- I don't know if this is one of the reasons mine is still working well, if I have just been lucky so far, or if you guys have just been unlucky.

TB

Hi TB,

Yeah tried varying the speed to no avail. I will try roughing the knurling up again and see if that makes a difference. I'm interested in the 'O' ring idea but no quite sure how to go about it. Don't suppose anyone has done anything like that (not you Zwickel, looking for cheap and cheerful)? As I see it the problem would go away if I could just get the idle roller spinning, a bit like the crank handle on an old motor.

 

[Zwickel]

Did you get new rollers from the manufacturer or did you make them up? And just to be clear, you think the problem was with the knurling on the rollers and the mill having to rely on the knurling to turn the idle roller?

Ive got the new rollers from manufacturer. The first 100kg of malt the mill worked a treat, no problems at all and the malt went through very quick.
But then it started to make troubles. First I didnt know at all what the heck the problem is, bcause I couldnt see the idle roller.
Later then, I realised its the idle roller that makes the trouble.

okay, first few times I could help it by cleaning the rollers (have brushed it) and it worked again for the next 10kg, then the problem started again.
Then I had to brush the rollers after 8kg, then after 6kg and so on. In the end I couldnt get even one kg through.

It seemed to me as the metal of the rollers would be too soft and the grip was fading.
The knurls of the new rollers have been very sharp, but after a little while it became blunt.

So I guess the metal is not hard enough.

Cheers :icon_cheers:

edit: spelling

 

[glaab]

I been thinking of buying one when I win the lotto but I'm having second thoughts after reading this thread. My little Marga is looking better all the time. I read somewhere that dampening the grain
will help it go through, IIRC it was about 50ml per kg, have you tried that?

 

[Zwickel]

.... I read somewhere that dampening the grain
will help it go through, IIRC it was about 50ml per kg, have you tried that?

thats certainly right, but the rollers are not made of SS, so I afraid they will be rusting.

Cheers mate :icon_cheers:

 

[AndrewQLD]

I will post a solution to you by email/PM.Its a bit of work but doesn't involve any mechanical reworking.
GB

Hey GB, how about sharing the love and posting your solution here? There could well be a few other brewers who could use your advice at some stage in the future.
I've got the MM2 and have crushed about 200 kg++ and haven't had an issue YET, but you never know what will happen, I for one would be interested in a non mechanical fix.

Cheers
Andrew