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ol' rummie 01-07-2010 10:54 PM

Mill Speed?
 
I've recently bought a Crankandstein 328D mill, the website recommends gearing it down to 200RPM. I have the equipment readily available to gear it down to 280RPM.
Will the extra 80RPM have an effect on the crush?

The Pol 01-07-2010 11:12 PM

Should be fine, look at your crush. They recommned running it slower because it will be less prone to shredding the husks. 80 RRM wont matter, I say roll with it.

nukebrewer 01-08-2010 12:43 AM

Quote:

Originally Posted by The Pol (Post 1793176)
...I say roll with it.

Was that pun intended?

ImaBrewinfool 01-17-2010 08:05 PM

I was once told by a brewery designer that the magic number is 15 inches per second face roller speed. Figuring a 1.5 inch roller would be 4.5 inches circumference, that would be 3 rotations per second, being 180 rpm as ideal speed for the roller.

hoppyray 01-17-2010 08:34 PM

1992 Zymurgy Special Issue on building your own roller mill called for aprox 100 rpm. I built one in 1995 with similar design and our LHBS now uses it exclusively! I will be building another one this summer almost identical to the old one, just more compact.

Cheers!

brewmonk 01-17-2010 08:51 PM

whats your equipment?
can you drop it a further 2:1 to 140?

ImaBrewinfool 01-17-2010 08:51 PM

Going by just the RPM is a less useful number because of the differing diameters of the rollers of the mills. Face roller speed is more useful as a measurement because of the variations in diameter of rollers. Say you have a 2" roller, that would make for 6" circumference, and 2.5 rps being 150 rpm. That is 20% difference in rpm vs my previous example. That is considerable variation, not to mention I would prefer a 2" roller because of a better crush over a 1.5", but you would lose all that advantage overpowering it by that much.

ImaBrewinfool

Catt22 01-17-2010 09:14 PM

IMO, the mill speed is not at all critical. You can adjust the mill gap to compensate one way or the other if need be. I like to mill on the slow side as it generates much less dust than high speed milling. I'm running my mill at 115 rpm which is relatively slow, but it still doesn't take very long to grind through 20 lbs of malt. All of the commonly available mills are capable of producing excellent grist. IOW, I have yet to see a roller mill that produces a superior grist, or an inferior one either for that matter, when compared to any other roller mill. The 280 rpm's should work just fine.

brewmonk 01-17-2010 09:38 PM

wow, good points. I just tend to slow it down for 'dust storm reduction', I get enough $^@&#$^ up my nose in my woodshop.

hoppyray 01-18-2010 12:47 AM

I used six inch diameter rollers. I believe the idea was that the larger the roller,(6-8")
the better "pinch" it would have on the grain. Grains are slightly heavier on one end and if the freely falls into the "pinch", there is a good chance your grain will be cracked in half(end to end). One of my design changes was to offset the hopper to allow the grains to fall against the roller before entering the "pinch" of the rollers. This gives the grain a better chance to be cracked along its length, which will help create an improved grain bed and better filtration in your mash lautertun. Many of the retail mills have 1-2" rollers that are knurled with a gripping pattern that pulls the grain into the "pinch". This tends to tear at the husk and can end up adding to husk astringency in your beer. The rpm used on a larger roller would be important as you would want to also give the grain a chance to lay parallel to the rollers/pinch. Smaller, knurled rollers are going to immediately grab the grain regardless on the speed. I guess if you saw the roller milled grain in comparison, you would understand the value of larger roller and no knurling on the smooth surface. They all work fine but if you are building your own mill, do everything you can to improve your efficiency.
Four or six roller mills would be better but two good size rollers work great.
I have a Glatt mill but much prefer to use the larger roller mill.

Best of luck !

Cheers!


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