Grain crush and mash efficiency

[Bubbles]

Lads, I'm getting some efficiency issues and low OG (1.040 from an expected 1.051) which I suspect is caused by the grain consistency coming from my new grain mill. I've only used the mill once and I thought the crushed grain looked a bit coarser than the pre-crushed grain I usually buy. I did think that some grains were barely cracked. However, I couldn't be sure and decided to trust the factory settings on the mill and mash in.

At the end of the mash, the grain definitely looked different from usual. I picked out some grains and it appeared some of the grains were not crushed through. Btw, I used the factory setting on the mill which is 0.05, though it's also possible to adjust the rollers (thinner at 0.025 and thicker at 0.1)

I'm not sure if this has any bearing, but I used a drill on a screwdriver setting and it flew through 5kg of grain. Would I get a different result from doing it manually?

So what would you do? I was thinking of grinding a few test bowls of base grain at the various settings and comparing them to the pre-crushed malt from the HBC. Do you think the 0.025 setting would result in lautering issues?

I should also mention that my volumes were pretty spot-on though my batch sparge temperature was well below what it should have been at 70C.

Thanks.

[Eoin]

If a lot of grains were not crushed then that's probably your issue. I BIAB, so I crush pretty fine and don't worry about stuck mash.

Sent from my HTC One

[Bubbles]

Cheers Eoin. So much of the grain looked perfectly crushed that I wasn't sure.

What mill do you use, and does it give any indication of the thickness of the crush?

[TheSumOfAllBeers]

If you are using a drill as a motor source, you could double crush the grain at the same settings.

Like you said, it will fly through the grain.

As a BIABer, we mill fine to boost our efficiency, but thats a risky strategy with a standard mash tun.

Some grains mill easier. I find malted barley mills easy, while wheat and rye kernels are smaller and can get through the mill intact, or only barely cracked. Roasted grains can be more difficult to crush as well for some reason (do they shrink as they roast?).

Possibly mill your base malt and your tougher/smaller specialty grains at different settings, or split your grist and crush one at a finer setting than the other, so you still have enough husks to keep your sparge flowing.

[DEMPSEY]

If you see uncrushed grains then that would have an effect on your SG. run it through a second time of adjust the gap. Slower speed will also give the rollers time to do there thing.

[Eoin]

I use a hand cranked Corona and I leave it set permanently.

Sent from my HTC One

[Damien M]

I had a similar problem with my new Millars M3 and got a few low efficiency ( low volume batchs )   I put it down to being over cautious on its first use and not over crushing. On subsequent batchs I tightened the gap and the locking screws . I use a drill too and the vibrations although good to get the grain moving, caused the gap to change!!!

I learned that the mill doesn't really effect the husk in that it comes away remaining mostly intact and they are the key to a good grain bed filter. 

Keeping in topic, does anybody have issues with the mill jamming as it gets overloaded with grain and the load of grain above it in the hopper??? I have started to put a cardboard cover about 2 or 3 cm above the rollers with a  slot (less than a 1cm) directly over the rollers to slowly feed grain on to the rollers. I'm still prototyping so looking for additional suggestions??

[Jacob]

Do you think the 0.025 setting would result in lautering issues?

No problems on my setup. Using fridge as a MT with 'bazooka' like filter.

[Bubbles]

Thanks for all the comments and suggestions lads. I have to confess, I never even thought of running the grain through the mill a second time.   

I think the first thing I'll do is tighten the rollers slightly and see what the resulting crush is like.

[Bubbles]

If you see uncrushed grains then that would have an effect on your SG. run it through a second time of adjust the gap. Slower speed will also give the rollers time to do there thing.

Ta Brian. I'm pretty sure I was using the slowest setting on the drill which is the screwdriver setting, is that right?

[Jacob]

If you see uncrushed grains then that would have an effect on your SG. run it through a second time of adjust the gap. Slower speed will also give the rollers time to do there thing.

Ta Brian. I'm pretty sure I was using the slowest setting on the drill which is the screwdriver setting, is that right?

Are you talking about speed or torque settings?
There's no speed control on my drill, just torque.

[Will_D]

If some grains are crushed and some are not I would check that the rollers are parallel to each other. If the gap is tapered that would explain the uncushed!

[Bubbles]

Are you talking about speed or torque settings?
There's no speed control on my drill, just torque.

Well, just torque actually. I used the lowest setting.

[Bubbles]

If some grains are crushed and some are not I would check that the rollers are parallel to each other. If the gap is tapered that would explain the uncushed!

The mill has three widths indicated on both sides of the roller and they both read '0.05' but you're right I should do a visual check on the widths between the rollers on both sides. Thanks.

[Ciderhead]

My new 3s was incorrectly set from new, I have feeler gauges
Pm me