Finer crush vs. coarser crush/ higher speed vs. lower speed

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Q2XL

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I was talking with a brew buddy the other day and the subject of milling grain with a Barley Crusher came up. We were discussing the speed of the crush and how it relates to the type of crush that you get.

The question that we have is this.... Does a faster speed with your drill motor- or whatever you use to power the mill, cause the crush to be finer or coarser?

Sometimes I think that the slower the speed the longer the grain is between the rollers and then a finer crush. On the other hand I can see how a faster speed would mean that the grain is being "pulverized" and then would mean a finer crush also.

Your thoughts.
 
I would think faster=more shredded husks because the force on the grains is greater. But physics was always one of my weaker subjects.
 
I have no personal experience with the topic but it sounds like an interesting topic for an experiment...

Just from thinking about it, I would think that the speed (on a BC mill) of the crush probably doesn't influence the crush nearly as much as the gap setting since it uses a two-roller setup. I'd be interested in hearing the results if you do experiment though!
 
I've always heard that you want to crush as fine as you can without getting a stuck sparge.. as a finer crush increases you efficiency..

And that you want to crush at around 200-300 RPM so that you reduce shredding of the husks.. I think shredding the husks results in off flavors or tannin extraction or something else undesirable...

I just used my new C&S 3d for the first time this morning... I powered it with my milwakee right angle drill which is pretty slow...

It's mashing right now, so I don't know what my efficiency is, but the crush looked 'really' nice....

As long as I didn't crush so fine that I get a stuck sparge (I set it to 0.040), then I should see a nice bump in efficiency compared to the crushes from the LHBS... or so it says in small print right here at the bottom of the page...
 
I would say that a faster crush would produce more shredding and ripping of the grain where a slower crush is more uniform. Generally to get a finer crush you would reduce the distance between the rollers rather than increase (or decrease) the speed of the mill
 
I drive my mill with a 1/2" Craftsman AC drill. It's not hard to hold the trigger at a setting that's pretty low, I'm guessing around 120-150 rpm. I get an excellent crush with a minimal amount of flour. My husks have some tearing, but I have zero problems lautering /sparging (I use a 10 gal. Rubbermaid MLT cooler conversion, with the Bargain Fittings braid kit), so I'm not really worried about it. It would be interesting to mill a few pounds at a higher speed, then the rest at the lower, just to compare. I suspect that'll be the only way to tell, since mills and gap settings differ. I use a "Victoria" branded Corona-type mill, with the plates set to about the thickness of a credit card.
 
I use a Dewalt, non-variable speed, 1/2" drill motor to power my Crankandstein 2s. When I first hooked it up and ran it full speed(about450rpm) the crush was ok, lots of shredded husks though. I then hooked up my dimmer that I use to control the temp on my brew belt, and tried that. I guessed at getting the drill to run about half speed. The crush was much better looking, maybe a bit finer, but hardly any shredded husks.
 
I just bought a Barley Crusher, used it last week, cranked it by hand, got a nice looking crush, but ended up with 60% efficiency. Fast forward to this week, 2nd batch, used a corded drill, my battery powered one was too weak, crushed it very fast, drill only has one speed, superfast. The crush was definitely finer, the husks were much more torn, and more flour. I used rice hulls on both batches, no stuck sparges, calculated 89% eff. on 2nd batch. I'm thinking my measurements are off a bit, probably not as low on the first and not as high on the 2nd, but using the drill definitely made for a different crush, and both were on the factory .039 setting.
 
the spectrum of particle sizes is typically adversely affected by raising impeller speed. the typical distribution of particles is the shape of a skewed bell, with the highest point being the mode of the product, where the largest number of particles of a given size occur.

increasing impeller speed has the affect of shifting the particle spectrum to the "left" on the sieve analysis diagram. in other words, the mode will become smaller, and the average particle size will become lower. the max particles will remain about the same, and the number of "fines" produced will be increased.

lowering the speed of the impeller has the opposite tendency. the slower you can mill, the more the mode shifts to the right, and the fewer the fines. of course, there is a limit to this, and that is the point where the impeller speed no longer produces sufficient force against the stator to grind the grain. at that point, the product will burn before it mills, with a large number of fines produced, little if any capacity, and no coarse product.

the optimal milling point for a granular, uniform result is therefore at approximately the minimum grinding speed, with a few rare exceptions.

NOTE: this post deals ONLY with ROTOR/STATOR mills. the speed effects of roller milling are entirely different.
 
the spectrum of particle sizes is typically adversely affected by raising impeller speed. the typical distribution of particles is the shape of a skewed bell, with the highest point being the mode of the product, where the largest number of particles of a given size occur.

increasing impeller speed has the affect of shifting the particle spectrum to the "left" on the sieve analysis diagram. in other words, the mode will become smaller, and the average particle size will become lower. the max particles will remain about the same, and the number of "fines" produced will be increased.

lowering the speed of the impeller has the opposite tendency. the slower you can mill, the more the mode shifts to the right, and the fewer the fines. of course, there is a limit to this, and that is the point where the impeller speed no longer produces sufficient force against the stator to grind the grain. at that point, the product will burn before it mills, with a large number of fines produced, little if any capacity, and no coarse product.

the optimal milling point for a granular, uniform result is therefore at approximately the minimum grinding speed, with a few rare exceptions.

NOTE: this post deals ONLY with ROTOR/STATOR mills. the speed effects of roller milling are entirely different.

In other words, this post is not relevant to the OP's question.

I've used all speeds and it doesn't matter for me. My mill (JSP maltmill) produces equal crush regardless of how fast I run it. I've been going full speed for a LONG time. I go for a fairly fine crush.

^This. The speed has no effect on crush size.
 
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