MillMaster Mini Mill slow after adjusting gap

[tallie]

Yesterday I narrowed the gap on my MillMaster Mini Mill from 1.5mm to 1.2mm as a step to address some mash efficiency changes I've encountered since upgrading to a Braumeister. After changing the gap, it took more than 20 minutes to put just over 6kg through, despite being exactly the same grain bill that I milled two weeks ago in around 5 minutes. I understand that narrowing the gap could have some impact the flow, but I don't think it's an unreasonable setting and I'm not aware of it taking that long for anyone else.

The grain looked like it was just rolling around on top of the rollers half the time, although there always seemed to be some bits going through and both rollers were always turning. I turn the mill using a variable-speed power drill and it didn't have the usual resistance that I've felt when working the drill previously. I tried different speeds, but it didn't make any noticable difference. I brush the rollers down after each use and they don't look "clogged" or anything. I use the perspex hopper that was made for the mill, which I removed when I changed the gap, but I'm pretty sure it went back on in the same position. Even towards the end when the hopper wasn't at capacity, it was still slow.

I can't think of anything else that would have changed. It might have been more humid here yesterday, but if anything, I would have thought that would help with pulling the grain through. I have noticed in the past that some grains don't go through as quick as others, but I don't recall it ever taking that long. Does anyone have any suggestions I might try next time to speed things up? I'd prefer not to have to mill twice on two different gap sizes. Can anyone else with this setup give me an idea on how long it takes for you to mill?

Incidentally, changing the gap did help a little bit with mash efficiency, but not as much as I'd hoped.

Cheers,
tallie

 

[vortex]

No idea why it would be so slow. I have the same mill albeit with a custom hopper which allows about 20kg of grain, never been slow or had any issues with pulling the grain into the mill even when the hopper is nearly empty.
I mill at 1.2mm and last brewday milled 14kg in about 15 mins (I mill slowly intentionally).

 

[Florian]

Tallie, from the way you describe it I can't help but think that the gap is too small for the grain you're using. You say some grain seems to be rolling around on the rollers but some also get through.

Could it be that the grains have to be in a certain position for the rollers to be able to grab them, pointy end down, for example? So basically the belly being to fat to fit through the rollers, unless the pointy end goes in first and drags the belly in?

EDIT: That obviously would explain why it would take so long to mill, as every grain needs to be turned into the right position first.
If you think this could be the issue then you could either live with it or slightly up your gap and see how that goes.

 

[tallie]

No idea why it would be so slow. I have the same mill albeit with a custom hopper which allows about 20kg of grain, never been slow or had any issues with pulling the grain into the mill even when the hopper is nearly empty.
I mill at 1.2mm and last brewday milled 14kg in about 15 mins (I mill slowly intentionally).

Right; that's about the speed I would be expecting.

Tallie, from the way you describe it I can't help but think that the gab is too small for the grain you're using. You say some grain seems to be rolling around on the rollers but some also get through.

Could it be that the grains have to be in a certain position for the rollers to be able to grab them, pointy end down, for example? So basically the belly being to fat to fit through the rollers, unless the pointy end goes in first and drags the belly in?

That makes sense, Florian, but I don't think I'm using particularly exotic grains. This was the grain bill for the last two batches:
43% BB Ale
32% Wey. Munich I
8% Wey. Carapils
8% Heritage Med Crystal
6% BB Wheat
3% TF Pale Choc

Now that you mention it, maybe one of those (I'm looking at you, BB Wheat) is causing the problem. Next batch will be a different grain bill, but I might run the each type of grain through separately to see if some are slower than others. Thanks for the hint!

Cheers,
tallie

 

[vortex]

Now that you mention it, maybe one of those (I'm looking at you, BB Wheat) is causing the problem. Next batch will be a different grain bill, but I might run the each type of grain through separately to see if some are slower than others. Thanks for the hint!

I doubt it. 60% Wheat 40% Pils wasn't an issue in mine @ 1.2mm.

How old is the mill? Is the knurling worn at all?

 

[tallie]

I doubt it. 60% Wheat 40% Pils wasn't an issue in mine @ 1.2mm.

How old is the mill? Is the knurling worn at all?

I can't remember exactly what the knurling was like brand-new, but I've only been using the mill for less than a year (20-25 single batches). It's fairly uniform across the entire width of the rollers - the centre of the diamonds aren't pointed, but the texture is there. I would hope that it's not that worn yet! I'll take a look at the new ones next time I'm at the shop to compare.

Cheers,
tallie

 

[Amber Fluid]

I cant tell you exactly what mine is adjusted to but you can barely put a credit card in the gap. I also use a motion dynamics motor and it usually chews through 5-6kg grain in well under 5 minutes on a slow speed through the same perspex hopper. This includes BB Wheat.

I have also milled about the same amount of batches (20-25) and all about 5-6kg grain. My mill still runs as good as the day I got it and it has no trouble dragging any grain through that I have used yet.

I know this doesn't help your problem, but I guess I am just trying to explain that I have used mine for about as much as you have yours and it's still as good as new. Therefore, it doesn't sound like a grain issue to me.

 

[vortex]

I have also milled about the same amount of batches (20-25) and all about 5-6kg grain. My mill still runs as good as the day I got it and it has no trouble dragging any grain through that I have used yet.

I know this doesn't help your problem, but I guess I am just trying to explain that I have used mine for about as much as you have yours and it's still as good as new. Therefore, it doesn't sound like a grain issue to me.

Ditto. Similar age and batches on my mill, still works as good as the day it was new.

 

[Florian]

Just thought of it, you haven't mounted the mill upside down after changing the gap by any chance?

I have the original MillMaster and have done that once, which resulted in grain getting stuck in the gears and because of this the shaft was harder to turn, therefore it took longer to mill.

Probably a long shot but thought I'd throw it out there, it's not that it hasn't happened before.

 

[tallie]

Thanks guys, the data points are helpful even if I'm still to get to the bottom of it.

And good thinking Florian, but the mill was bolted to the base the whole time - I removed the hopper to set the gap. There is a gear guard built in to that hopper too.

 

[booargy]

I found with a 1mm gap ale malt it wouldn't catch but pilsner malt would. So I moved the gap to 1.5mm and it goes through easily. But I also mill into a bucket then through again onto the mash water.

 

[bignath]

Tallie, I have experienced the same problem to you fairly recently. Grain struggles to get dragged through... You can feel it in the drill that it isn't taking properly etc... I was at .9mm so I opened the gap to 1.5mm. Worked fine again. Closed it back to 1.2-1.4 and still works sweetly but now I crush twice. Second run only takes a minute.

Haven't gone back to under 1mm yet.

I'm convinced its a knurling issue. My old Crankenstein had a really aggressive pattern on it, much more so than the mini mill.

Maybe our mills were built on a Friday afternoon?

 

[Batz]

So geared mills are not all they are cracked up to be?

My old Valley Mill, one driven roller now over 10 years old and never missed a beat. :beerbang:

 

[bignath]

So geared mills are not all they are cracked up to be?

Ahh, I see what you've done there batz.... Very clever.

But I'd be inclined to agree re: geared rollers. I personally couldn't have cared less about the gears. The main reason I 'upgraded' was the quick gap changing method. PITA on a crankenstein 2 roller entry level mill.
As I was changing brew rigs toward a biab style rig, I wanted ease of adjustment to dial it all in.

Still love my mini mill, just wish the knurling was a bit more angry. Old mans a metal fabricator....might give it to him to re-knurl.

 

[Batz]

Just stirring the pot a bit Nath.
I'm a bit surprised that brewers are having trouble with these mills, I know the old model was a ripper. I though if and when my mill finally dies I would go a Millmaster because of the two driven rollers. I wonder if there maybe another problem you are over looking?

As I said my old Valley must have had many tonnes of grain put through it in it's life, I just hope it keeps going.

Batz

 

[Smokomark]

I had the same result when i dropped my gap from 1.5mm to 1.3mm.
The mill would process 8-9kg in about 5 mins at 1.5mm. Once i dropped to 1.3mm it took about 20 mins.

Doesn't really bother me as I just have to upend a 30lt fermenter ( with large funnel attached to lid ) full of grain into the perspex hopper, hit the on switch and walk away.

It gives me a bit of time to check over the brew rig and pour a beer.

 

[mikec]

Could the drill be slipping?
Increased resistance from tighter gap, drill is spinning but mill not so much.

 

[tallie]

I had the same result when i dropped my gap from 1.5mm to 1.3mm.
The mill would process 8-9kg in about 5 mins at 1.5mm. Once i dropped to 1.3mm it took about 20 mins.

Doesn't really bother me as I just have to upend a 30lt fermenter ( with large funnel attached to lid ) full of grain into the perspex hopper, hit the on switch and walk away.

It gives me a bit of time to check over the brew rig and pour a beer.

Somewhat comforting to know I'm not the only one, although it's still less than ideal. My mill isn't setup to run hands-free at the moment, so I can't just let it run in the background while I do other stuff.

Could the drill be slipping?
Increased resistance from tighter gap, drill is spinning but mill not so much.

Another good thought, although given that the shaft is keyed for the handle, I think I would have noticed it slipping if it wasn't tight enough. I'll still look out for that next time.

I'll also take the mill into the shop and compare the knurling side-by-side with a new one.

Cheers,
tallie

 

[vortex]

Are you simply trying to mill too fast? IE drill going too fast? I have my drill set on the slowest speed (most torque) and only use about 1/2 "throttle". When there is the last few grains in the hopper (I'm talking probably 10 - 15 actual grains) a few bounce around a little, but no real issues pulling them through.

I'd also build a bigger mill hopper, 1.x kg really isn't big enough, you'll be there all day just pouring malt in!

 

[tallie]

Are you simply trying to mill too fast? IE drill going too fast? I have my drill set on the slowest speed (most torque) and only use about 1/2 "throttle". When there is the last few grains in the hopper (I'm talking probably 10 - 15 actual grains) a few bounce around a little, but no real issues pulling them through.

I'd also build a bigger mill hopper, 1.x kg really isn't big enough, you'll be there all day just pouring malt in!

I usually go reasonably slow; always on the lowest gear and rarely over half throttle. I tried a few different speeds, including running it at the point that it would occasionally stall when it finally seemed to take hold of a decent amount of grain, but once that got through, it would just roll around again, not taking much in.

And yes, I do have a PVC leaf catcher pipe fitting that I use to extend the hopper up to about 4kg capacity