New grain mill, now getting rubbish efficiency?

[Sadu]

Hey everyone,

Missed my target gravity by 11 points this morning for the second time in a row. Was trying to figure out why, then I realised that these last 2 batches I have been milling my own grain. So that has to be the problem. Efficiency for both these batches was 63%, prior batches using the same process were getting 78-85%.

So I have a couple of questions I'd like to ask about how to use a grain mill, since I apparently can't figure this out myself.

My mill is brand new, the 2-roller type with a hand crank (http://www.trademe.co.nz/Browse/Listing.aspx?id=1117292064). It has adjustments either side for bringing one end of one roller closer to the other (so you can have a different gap at each end of the roller. I noticed that only one roller is powered by the crank, not both. I don't know if this is normal or not.

I found that if the gap was too wide the grains go straight through without splitting. If I adjusted it the slightest bit closer then the handle will just spin without pulling any grain through. There is a marking that says 0.055, I did my crush slightly finer than this (maybe 0.050). I don't know what units this is but I read in a few places that 0.038 seems standard, I definitely wouldn't have been that fine and when I tried the grain stops flowing. I ran the grain through twice at the 0.050 setting. If I compare my crush to the HBS crush mine has a lot more whole grains in it and is much chunkier, and I think the efficiency drop speaks for itself.

Does anyone have any advice on what to do to get a finer crush but keep the grain flowing? As soon as I tighten the setting it stops feeding grain. Feeding the grain through twice doesn't seem to help.

Secondly is it normal for the second roller to not be powered? Maybe my unit is faulty or it's just a bad design.

I'm not really happy with 63% when I can get 20% more from the same process with the HBS crush. Appreciate if anyone has any ideas or if I should send the thing back.

 

[schematix]

Get yourself a set of feeler gauges (cheap) and see what your actual gap is. 0.055" seems quite huge to me.

And yes the second roller is just an idle roller. Totally normal for home brewing.

 

[hottpeper13]

You should be able to power that with a small drill, that speed helps pull the grain into the idle roller.

 

[kh54s10]

Conditioning the grain might help also. Get a spray bottle and mist the grain, stir mist more, stir until the surface of all individual grains are slightly damp. Then mill them.

You also want the rollers even. Don't set one end closer than the other end.

Get the gap as tight as you can without getting a stuck sparge. This will take trial and adjust. Tighten up until it looks like trouble then back off a little.

Second the use of feeler gauges. You can get them at a hardware or automotive store.

 

[brewbama]

Just to add to the good input above: when I got my grain mill I had the same bit of trial and error. Adjust it to a tighter gap and use a drill were the keys to my success as well.

 

[wilserbrewer]

I found that if the gap was too wide the grains go straight through without splitting. If I adjusted it the slightest bit closer then the handle will just spin without pulling any grain through.

Secondly is it normal for the second roller to not be powered? Maybe my unit is faulty or it's just a bad design.

Sounds to me like the handle is not properly tightened on the mill shaft if it is spinning? The adjustments are sensative, too loose will give a lousy crush, and too tight will not flow the grain. When you say the handle just spins, are the roller turning as well?

 

[Sadu]

Thanks everyone, this was really helpful. Problem solved.

With this mill you set the adjustment knobs on the side, then there is another nut on each side which locks the setting in place.

Since I was having such trouble getting this thing to work I wasn't tightening that nut hard enough - just making life easier for myself since I was having to keep adjusting it. What I think was happening was one of the nuts slipped as soon as I started on the crank handle and this threw the roller out of alignment. Seems if the roller isn't perfectly aligned then it won't feed properly.

So this time I set both sides to as close to 0.030 as I could, cranked those nuts nice and tight, and magically it works. Seems like a nice fine crush for BIAB now.

I'm curious why everyone seems to use electric drills on these though. I hand-cranked 4kg on the weekend (admittely this is a smallish grain bill) which didn't seem like that much of a hardship.The slow part was refilling the hopper and faffing around with the settings more than the actual grinding.

 

[stella_tigre]

We started doing a double grind, it seems to ensure fewer uncracked grains. Not sure what we've got for a gap but HWMO likes to use the drill also. We usually run about 12 lb on our grainbill. Last couple of brews have netted better than 70% doing biab (calculated values used 70 but we got several points higher,) but I suppose I should go plug in my numbers to get the actuals

 

[schematix]

Ive been using a $19.99 refurb Ryobi 3/8" drill for years. Always hurt my wrist and inconsistent speed, but did the job.

Just bought this, about as close to automation i'll ever get for milling: http://www.harborfreight.com/1-2-half-inch-heavy-duty-spade-handle-drill-93632.html

Look up malt conditioning too.

 

[MaryB]

Rotator cuff surgery twice on the right, torn rotator cuff still left, carpal tunnel both wrists... I use the drill!

 

[unviewtiful]

Thanks everyone, this was really helpful. Problem solved.

With this mill you set the adjustment knobs on the side, then there is another nut on each side which locks the setting in place.

Since I was having such trouble getting this thing to work I wasn't tightening that nut hard enough - just making life easier for myself since I was having to keep adjusting it. What I think was happening was one of the nuts slipped as soon as I started on the crank handle and this threw the roller out of alignment. Seems if the roller isn't perfectly aligned then it won't feed properly.

So this time I set both sides to as close to 0.030 as I could, cranked those nuts nice and tight, and magically it works. Seems like a nice fine crush for BIAB now.

I'm curious why everyone seems to use electric drills on these though. I hand-cranked 4kg on the weekend (admittely this is a smallish grain bill) which didn't seem like that much of a hardship.The slow part was refilling the hopper and faffing around with the settings more than the actual grinding.

I have a similar mill and if I don't have the rollers perfectly even, they grind against the side of the mill and bind up. Be sure to hold the adjustment knobs in place when you turn the screw that locks them in place. And tighten those suckers pretty good, if they come loose you'll lose any and all consistency in your crush.

Rotator cuff surgery twice on the right, torn rotator cuff still left, carpal tunnel both wrists... I use the drill!

Better reasoning than me, I'm just super lazy!

 

[wilserbrewer]

Better reasoning than me, I'm just super lazy!

Im so lazy that holding the drill was too much work, both of my mills are rigged on a stand with the drill fixed, allows you to do other tasks while the grain is being milled.

 

[CascadeOK]

Doing biab...I'd definitely go for a fine crush. I have a Wilser bag (check out his post above). It's a fine weave so you can crush those grains fine.

Which is only really relevant because I can buy a 5 gal kit, scale up the water to 5.5 because I want to NET 5 gal in my keg after losses (why waste drinkable keg space after all that effort). Now I consistently get over 80% efficiency. Also being lazy I let my local brew house crush the grains the first time and I crush them finer at home. Works for me.