The dreaded grain mill issues thread

[IslandLizard]

Northern Brewer said they had a returned grain mill that was in working order. They're shipping that out. Said I can use that as is or for parts. It's supposed to be here Tuesday.

Lucky you!
That's finally some good news, and a very decent offer from them. Hopefully it wasn't returned for a similar issue.

You've not been milling (whole kernel) rice on your mill, have you?

 

[rtstrider]

I've run maybe 2lbs of it through for testing purposes over the whole time but that was way after these issues started. Anywho I'm hopeful this new replacement works and will hold up for many batches to come

 

[IslandLizard]

I've run maybe 2lbs of it through for testing purposes over the whole time but that was way after these issues started. Anywho I'm hopeful this new replacement works and will hold up for many batches to come

If the steel is too soft for the milling application, I wonder if you could harden it...

 

[rtstrider]

If the steel is too soft for the milling application, I wonder if you could harden it...

You know I wouldn't even know where to begin with that lol

 

[IslandLizard]

You know I wouldn't even know where to begin with that lol

There are machinists on the forum, maybe start a thread on that?

It's basically heating to certain temps, holding it there for some time, then cooling it down quickly, like dropping it into a vat with water or oil. It would help knowing the alloy used, but I reckon it's some mild steel, and was never hardened. Most of that stuff is made in China, with wildly varying or non-existent QC.

There are methods to test the hardness of the steel you have on hand.

Your existing rollers good be re-knurled, then hardened too, but unless you know someone who takes homebrew for doing it, the cost is likely more than a new Monster or Crankenstein mill.

 

[Saunassa]

My hull wrecker has worked well for me, roller spacing is 30-34 mils depending on which credit card I used to check. A gap less thenp 25 mils and the grains would sometimes 'ride' on the rollers.
I was given a MM3 w/2" rollers and hopper extension. This beast with a big drill is amazing but will not fit on shelf like the hull wrecker will.

 

[rtstrider]

There are machinists on the forum, maybe start a thread on that?

It's basically heating to certain temps, holding it there for some time, then cooling it down quickly, like dropping it into a vat with water or oil. It would help knowing the alloy used, but I reckon it's some mild steel, and was never hardened. Most of that stuff is made in China, with wildly varying or non-existent QC.

There are methods to test the hardness of the steel you have on hand.

Your existing rollers good be re-knurled, then hardened too, but unless you know someone who takes homebrew for doing it, the cost is likely more than a new Monster or Crankenstein mill.

Monster Mill 3 is the end goal. Right now my brew funds are being saved for an All in One setup. I like the Foundry but I'm really trying to hold out for the Brewzilla 4th gen when it's available. Once that's done and I get all the stuffs (brew bag, CASS chiller, various different add on's and nylon insulator sleeve, etc) I'll start saving for the grain mill...After that though it'll be time to convert the Pin Lock keg fittings to ball lock and then invest in real beer taps instead of the cobra taps lol. Still have a ways to go, but, it's awesome to see how much equipment has been gathered over 5 years of brewing too!

 

[IslandLizard]

Monster Mill 3 is the end goal.

Beware, from what I've read it's a real hassle to adjust the gap for different grain sizes on an MM3.
My MM2, like most 2 roller mills, is easy for that.

 

[Broken Crow]

If the steel is too soft for the milling application, I wonder if you could harden it...

Unfortunately no... I used to do heat treating; A shaft for such an application is first carbed & hardened, then drawn back down to a softness/hardness appropriate to the application, and then, (importantly straightened..[As the process will alway warp the part to some degree], only after this are your knurls, cutting edges or whatever, then machined into the shaft. Trying to do it all after machining wrecks edges. It also changes the size and fit ever-so-slightly, and it's a crap shoot from the get go if it's even an alloy suited to heat treating.
(sorry I can't give a more detailed explanation, I lost a lot of that to brain-injury)

 

[rallenhall]

I have an MM3, and have no interest in changing the gap that's set for my preferred barley malt crush. I kept my first mill, a two-roller Barley Crusher, primarily for its easy adjustability and use with specialty malts such as rye.

 

[Nate R]

Beware, from what I've read it's a real hassle to adjust the gap for different grain sizes on an MM3.
My MM2, like most 2 roller mills, is easy for that.

Yes, this!!
I have the basic MM3 setup.
It is quite difficult to re set gaps effetcively.
This mighr be user error, or at least 10% or more user error for sure.

Looking back... i wish i had spent a little more for an "all in one" grain mill motor combo. Buy once cry once etc.
Back when i bought it was pushing $600... now i have seen good deals for like $400.
And a bunch of good deals here on the for sale forum.

 

[Saunassa]

I have an MM3, and have no interest in changing the gap that's set for my preferred barley malt crush. I kept my first mill, a two-roller Barley Crusher, primarily for its easy adjustability and use with specialty malts such as rye.

Yep my MM3 came adjusted by former owner and it works fine for me, I am not going to touch it unless I have no choice.

 

[rtstrider]

Just received the used replacement mill. The rollers are rusted...At least they tried lol I'll see if the rust can be knocked off with a wire brush later and report back

 

[pocketmon]

Reverse the rollers, widen the gap, and/or condition the grain. These are what I learned from this forum.

 

[Mark3885]

Try evaporate rust from harbor freight, I hear it works great and easy to use.

 

[jwa120]

Seems like the majority of grain mill issues come down to worn rollers. I use a corona mill, which is pretty much bullet proof, but you don't get the same quality of crush as a roller mill. If I was going to upgrade I would definitely be looking for something with harden rollers. The only lower priced option I know of would be AIH's cereal killer. On the upper end, monster mill offers hardened steel rollers on their pro mills.

The geared mill options look enticing, I assume they would help with the worn rollers issues. I'd would prefer harden rollers over geared, but that's not based on experience.

Hopefully those rusty rollers work out and buy you a year or two before you need to reassess the issue.

 

[IslandLizard]

Hopefully those rusty rollers work out and buy you a year or two before you need to reassess the issue.

If the roller material is indeed that soft, (wet) conditioning the malt before milling may extend their useful service by a few more years. Also keeps the dust down.

 

[Dr_Jeff]

I would think that just running some malt through would knock the rust off.
It would just add a tiny bit of iron to the beer, seems like a win/win.

 

[IslandLizard]

I would think that just running some malt through would knock the rust off.

Use old or cheap malt, that will be thrown away after the rust removal, or kept and clearly marked for just that purpose.
I've put a stainless wire hand brush on my MM2 rollers when a few rust spots had appeared on the bottom of the knurls. Easy peasy.

 

[rtstrider]

I was able to knock the rust off with a metal brush. The rollers they sent feel like they have way more bite than the ones I currently have. I do not have allen wrenches or a philips screwdriver at the moment so I am unable to replace the rollers. As a last ditch effort I did try cleaning the "crummy" rollers with 90% rubbing alochol on a rag. Going to leave it out to air out for a bit and will run 12.5lb grain through it this evening to test.

 

[rtstrider]

Wanted to report back. I let the grain mill rollers dry off then ran a thin soft rag through it back and forth a few times for giggles. Just double crushed 12.5lb of grain perfectly! Guess that means I'll probably be going the 90% rubbing alcohol route for a bit to see how long this holds. Either way glad I found a nice hack for the meantime!

 

[Bassman2003]

I have read positives and negatives about many different mills. Some expensive. I replaced my Barley Crusher after its rollers quite grabbing the grain. Same issue as you are having. I sent the rollers back to the maker and he sent them back "refreshed". They worked for a little while and then stopped grabbing the grain again. It is the use of cheaper materials for the rollers.

I went with the Cereal Killer as as the rollers are made with hardened steel and the price was very affordable. The performance is very nice imho.

 

[tennesseean_87]

I am about to brew for the first time with my MM3G.

I think the 1.5" rollers, the larger initial gap, and the gears will hopefully prevent this sort of thing from happening.

I built my own platform and hopper which covers the sides of the mill which is removeable. By removing the hopper, I can get a straight feeler gauge in to set the gap. Otherwise, you need an angled feeler gauge to get in between the driven and adjustable roller.

 

[tennesseean_87]

I started with a wide gap of .045 and milled a little bit. It seemed there were a fair number of large pieces that were just barely cracked. I dumped the first bit of grist I tested out back in with the rest, then set the gap to .040. The crush looked better here, and it seems I'm having a much better recirculation (eBIAB setup) during the mash than I was getting with my Corona, and a lot less flour, too! We'll see how my efficiency turns out.

I did actually have issues with the grain catching in the rollers once I poured back in the bit to double-crush at the tighter gap. No issues before that, so I'm chalking it up to the size of the pre-crushed particles no feeding through the gap at the bottom of the hopper or something. A little stirring in the hopper and it was right as rain.

 

[jambop]

I started with a wide gap of .045 and milled a little bit. It seemed there were a fair number of large pieces that were just barely cracked. I dumped the first bit of grist I tested out back in with the rest, then set the gap to .040. The crush looked better here, and it seems I'm having a much better recirculation (eBIAB setup) during the mash than I was getting with my Corona, and a lot less flour, too! We'll see how my efficiency turns out.

I did actually have issues with the grain catching in the rollers once I poured back in the bit to double-crush at the tighter gap. No issues before that, so I'm chalking it up to the size of the pre-crushed particles no feeding through the gap at the bottom of the hopper or something. A little stirring in the hopper and it was right as rain.

I think what you have to be aware of is that sometimes the grains look intact but on closer inspection that are actually well crushed but the many of pieces are contained within the husk. This is actually preferable to them being pulverised if you are brewing all grain with a recirculating wort system. The brew liquor gets through to the starches when mashing just as well but the wort also goes through the grain bed much better. This leads to a much better sparging phase. I did a brew on Tuesday with a crush at 0.059" many would have said was barely enough many grains still looked whole and unbroken BUT take one and press it and the centre just crumbled out once mixed with the hot liquor for mashing the insides of the grains swell and burst out of the husk... 93 % mashing efficiency and 83% brewhouse I am very pleased with that . Of course many do BIAB but I am still convinced even they could do better with a course crush to aid sparging the grains. I was on an English Malt producers web site yesterday and the production manager was saying that the ready crushed base malts they supply to their customers is currently crushed at 1.6 mm or 0.062 " ! This they say will give the best efficiency in terms of conversion and recovery for the brewers .

 

[Bobby_M]

.059 for BIAB seems absurd to me. At my homebrew shop, my BIAB crush is set to .020" and the normal crush for false bottoms is .032". If the kernel is just barely cracked, the conversion time is going to be much longer than it could be.

FYI, most people that use BIAB do NOT sparge at all.

 

[jambop]

.059 for BIAB seems absurd to me. At my homebrew shop, my BIAB crush is set to .020" and the normal crush for false bottoms is .032". If the kernel is just barely cracked, the conversion time is going to be much longer than it could be.

FYI, most people that use BIAB do NOT sparge at all.

Yes not disagreement but I do all grain brews and the numbers do not lie . I have found with the equipment I have which is a Grainfather S40 if I crush too fine I lose efficiency in mashing due to poor wort flow through the grains and the sparging phase of the brew . I upped my crush gap from 0.045", the recommended gap by the mill manufacturer, to 0.059" because of the flow situation and the reward was an increase of 7% in both mash and Brewhouse . I actually changed on the advice of a maltsters production managers advice but you have to recognise that this man knows his grains and they vary in size from year to year. At the moment he is sending out pre-crushed grain to professional brewers at a mill setting of 1.6mm for this years grain ... I am not going to argue with him he knows what he is talking about. I always mash for 90 mins in a single temp infusion but with modern well modified malts nearly all of the starches are converted in the first 30 mins . My notes from my last brew show a wort SG of 1.046 @ 15 mins mash time, 1.066 @60 mins and 1.069 @ 90 mins .
My main gripe is the 10 % I lose between the mash and the FV it is always the same 10% figure and due to less than great sparging and hop wort absorption . What is really interesting is that with my kit sparging the grains accounts for 22.6 % of the total final gravity !

 

[JohnDBrewer]

I run a 3 vessel RIMS and mill at a
.055 gap. I always check a handful of grain to make sure they are getting cracked and a slight crush. Occasionally I get some grains that are too small and I adjust. I had some Sekado Czech pils last summer and the kernels were smaller. My mash efficiency usually runs +/- 78% which I'm good with. I've tried going tighter and wider, but efficiency was not as good unless I used rice hulls on the tighter crush.

Forgot: I use a three roller mill. I'm not sure the 2 roller gap setting would be the same but that just feeling as it seems people mill much tighter on a 2 roller mills.

Thoughts on 2 roller v 3 roller gaps?

 

[tennesseean_87]

Another update from yesterday's second brew, a quad at 1.092 with 2lbs sugar and 16.X lbs grain. I tightened the gap to .035" for this one one after the .040" on the 1.050 brown.

Recirculation was still way better than my Corona crush, and I hit planned 70% efficiency on a bigger beer. The brown ale at average strength got 68-9%, which isn't far off, but I usually lose efficiency on higher gravity beers. This may have partially been due to the 90 minute boil and a little extra water to compensate. FWIW I do a dunk sparge for a few minutes in a 10 gal bucket with some stirring.

The grain feeding was flawless, confirming that it was the re-milling of the first bit as I was dialing in my crush that caused the issue with the brown ale batch.

Re: some of the debate above about gap size, it seems the maltsters supplying pre-crush probably have in mind commercial setups which may vary from a home-brew setup, especially BIAB. I've read that the courser crush that enables better recirculation gives the best efficiency for eBIAB. In the past I've noticed looser crush giving me worse efficiency, and I've had issues with recirc rate. So far the MM3G seems to be giving me better recirc rates and about the same efficiency (maybe better for the quad mash), which at least frees me from babysitting the mash to get other stuff done. The Corona seemed to yield a fairly inconsistent crush--some large/whole, lots of small particles and flour. I may try a bit tighter to see how that works out. I may also try a different 'sparge' manifold for the recirc to see it that helps efficiency or recirc (I currently recirc back into the center of the mash a few inches deep with streams pointing out).

P. S. the whirpool return I also recirc through allows more power to be used in step mashes without bag burning or scorching. Thanks for the idea on that, @Bobby_M . Thicker mash with a sparge also helps these steps go quicker.

 

[Saunassa]

My 2 roller has to be set credit card width so 32 to 35 mils in order to get decent efficiency. Downside was not lots of intact husk to help with biab draining and dunk sparge.
My MM3 with 2" rollers the previous owner recalled it is set between 45 to 50 mils so I left it alone for ebiab with pump. leaves fairly intact husks yet grain is crushed and no stuck sparge during circulation.