Faster milling = Higher efficiency?!

Uh, that is what it seems like.

Had hooked a cordless drill (r.i.p.) to my Corona mill (I don't want to hear about it! Works for me) and it worked well. Until the useless drill finally died. So back to hand cranking. Was originally getting 60% efficiency whether hand cranking or using the drill. One day I tweaked the tightening screw on the plates a bit for the hell of it. 70% efficiency.

Tired of going through cordless drills I bought a corded drill recently because I needed it around the house. Last 2 brews I used it on the drill. Wicked faster than my cordless ever was even not at full bore (variable speed). Last 2 brews were also 75% efficiency!

Does speed have an affect on efficiency?

my best guess would be the higher torque of the drill is pushing grain through harder and effectively crushing the grain against itself as well as the mill.

jay4e said:

my best guess would be the higher torque of the drill is pushing grain through harder and effectively crushing the grain against itself as well as the mill.

Click to expand...

+1 It doesn't make any sense. We know that if the gap is the same that you would extract the same amount of sugar, creating your efficiency. It is possible that your faster milling can up your points. However, only if the gap changes with how fast you mill. Maybe that's a Corona mill thing. You've said that it works for you, which I believe. Now you just need to figure out how it works.

I had the exact same problem you did regarding the cordless drill. Yesterday we went through two batteries and enough was enough. I grabbed my corded drill and it was like night and day.

Here is a couple of pictures:

Did you get a higher efficiency?

Not sure as it was my very first all grain brew.

I started using a corded drill a month ago (did about 5 batches with cordless drill) and my efficiency went from %70 to %80. The grain mills SOOO much faster it is insane. It almost made me question if I had done something wrong...

Since I purchased my barley crusher I've used a corded drill. I have noticed an increase of about 10% from the mill at my LHBS to my own. But I'm not sure the milling speed would increase your efficiency.

I remember hearing before that if you mill using a drill you should try to run the drill as slow as you can with out stalling. I think it had something to do with shredding the grain rather than crushing if you run it to fast.

jcb317 said:

I remember hearing before that if you mill using a drill you should try to run the drill as slow as you can with out stalling. I think it had something to do with shredding the grain rather than crushing if you run it to fast.

Click to expand...

yeah, as I said I did not run it at top speed. Regardless it was faster. Have not had any flavor problems from tannin extraction and the husks are no more torn then usual.

jcb317 said:

I remember hearing before that if you mill using a drill you should try to run the drill as slow as you can with out stalling. I think it had something to do with shredding the grain rather than crushing if you run it to fast.

Click to expand...

Most of the grain crusher specs say to run them near 300 RPMs. Many drills corded and cordless spin at around 300 RPM in the higher gear setting and around half that (150 RPM) at the lower gear setting. I've tried it both ways and have never really noticed any efficiency change based on speed. My 2 cents anyway...