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Old 01-11-2010, 04:05 PM   #1
Yavid
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Just wondering what everyone's opinion is of a 3 roller malt mill vs a 2 roller mill. Is the third roll actually beneficial? I've never really understood how a 3 roller mill functions. I understand that in most 3 roller mills the first two rolls are fixed and the third roll is adjustable but when you adjust roll 3 closer to roll 2 isn't it getting farther away from roll 1? Won't the malt just travel the path of least resistance (ie: through the larger gap)? Can anyone explain the idea behind a 3 roller mill to me?

 
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Old 01-11-2010, 06:44 PM   #2
IwanaBrich
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I was wondering the exact same thing.

I was "told" that the 3 roller mill gives a better crush because the grain is crushed twice, with the first gap set at .060" and the second a little more aggressive. That said, I was also "told" that the larger the roller the better the crush, so a mill with two 2" rollers may be better that a three 1.5" rollers. So I was leaning toward the Monster Mill that has two 2" rollers. All that said I was also "told" that the Barley Crusher is great mill and it uses two 1.25" rollers. Needless to say I'm terribly confused!

 
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Old 01-11-2010, 06:59 PM   #3
whalenutz
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IDK but as soon as mine gets in from Brewmasters Wearhouse ill post pics and let you know about how the third roller moves i believe that the third roller moves up between the the two fixed. as for movement of lest resistance would be true but the rollers are going in a fixed direction clockwise, my two dollars

 
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Old 01-11-2010, 07:31 PM   #4
Yavid
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I am very interested to hear how it works.

On all of the three roller mills that I have seen the third roller is mounted on an eccentric shaft or bushing. That means that the gap between roller 1 & 3 and the gap between roller 2 & 3 will only be even when the eccentric is centered between the two rolls (ie: roller 3 is at the TOP or BOTTOM of the eccentric). In any other position the gap will be uneven. Because of this common sense tells me that roller 1 will always turn clockwise, roller 2 will always turn counter clockwise and roller 3 will turn counterclockwise when the gap is larger between roller 1 & 3 and clockwise when the gap is larger between 2 & 3. When the gap is even roller 3 will likely "wobble" one way and then the other.

I'm probably WAY over-thinking this. I am trying to design my own mill and I'm wondering if it is really worth adding a third roller. Right now I am leaning towards a two 2" roller mill with both rollers driven and one adjustable. I just can't see the advantage of the third roll.

 
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Old 01-11-2010, 08:39 PM   #5
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I have 2 mills. One is a 3 roller and one is a single larger roller.
The 3 roller is an inverted pyramid with the bottom roller being the drive roller. Of the 2 top rollers one is adjustable and it seems to be on a cam so it is equal distance between the other top roller and the bottom roller.
The single roller mill just adjusts out from a curved plate. Not sure what it is set at as for distance.
Anyone know what the optimal distance is? I have my 3 roller set at .039.
I'm also not sure if there is an advantage over a 2 roller VS a 3 roller.

 
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Old 01-11-2010, 08:41 PM   #6
Yavid
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Thanks for the reply. Am I understanding you correctly that you have both styles of mill but aren't sure you see an advantage with the three roller over the two roller?

 
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Old 01-11-2010, 08:48 PM   #7
Elshauno
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I think 3 rollers would be better for a motorized mill to ensure it got a good crush at a higher rpm crushed twice. Plus more surface contact with 2". But if your just crushing by hand I dont think the size of mill will make much of a difference.

 
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Old 01-11-2010, 08:55 PM   #8
Yavid
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Thanks for the replies everyone.

I actually plan to run my mill fairly slowly (around 150rpm). I'd rather increase capacity by going bigger rather than running faster. I have a 2" x 30.5" long chunk of stainless round bar so I can either build a 2 roller mill with 15" long rollers (12" working surface) or a 3 roller mill with 10" long rollers (7" working surface). In either flavour I plan to drive all of the rolls. The 3 roller mill will add complexity and will cost a bit more (2 extra bearings, an extra pulley, longer belt, etc). I need to justify the third roller before I'd be willing to spend the extra money on adding it.

 
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Old 01-11-2010, 09:01 PM   #9
HBHoss
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Quote:
Originally Posted by Yavid View Post
Thanks for the reply. Am I understanding you correctly that you have both styles of mill but aren't sure you see an advantage with the three roller over the two roller?
I have a 3 roller and a 1 roller. I haven't used the 1 roller yet but heard it does a great job on the crush. I just measured the distance between rollers and the top 2 are set at .047 the distance between the bottom roller and the top roller is .037 giving a second finer crush to the grain.

 
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Old 01-25-2010, 04:22 AM   #10
BrewBeemer
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Yavid; on my MM3-2 the centerline of the top two roller bores to the lower centerline of the single adjustable eccentric adjustment without the eccentric installed I come up with the same measurement distance apart.
Looking at the plate from the roller end view, (inside the mill), top left driven roller, top right drive roller. If the top right drive roller is turning CCW it is pulling the grain thru the other top driven roller that must turn CW by the grain for the 0.060" crush. With the eccentric gap set tighter to the drive roller this bottom roller will turn CW driven directly by the drive roller from the already precrushed 0.060" grain, the wider gap between the bottom adjustable roller and the top left driven roller are both rotating in the direction to both push the grain back up not down thru the wider gap. Like you running up a down escalator both rollers acting on the grain. In this position the tighter gap adjustable roller is driven by the grain between it and the drive roller. To rotate the eccentric to the left the bottom roller will change from a CW to CCW rotation plus must be driven by the left driven roller. This will compound the slippage amount being rotated by a already driven roller above by the grain alone vs directly off the right drive roller. If you insisted on setting your gap between the two driven rollers the bottom adjustable roller will wants to push the grain up while the right drive roller with a wider gap wants to push grain downward vs going thru the set tighter second gap. Clearly this is a bad idea, for one two opposite directions to keep the gain up in the mill vs two rollers in the same direction keeping the gain up in the mill plus your then using the top driven roller to drive the second adjustable roller that's driven doubling the possiblity of grain slipping between two rollers vs one. This make any sense now? See the two bad reasons? One should remember to set the gap against the drive roller not the top driven roller on the MM design of mill. With the extra cash at hand I knew I wouldn't be happy with a 2 roller so went for the 3 roller of 2". Case hardening was just added icing on the cake plus free only a 3 mile drive. I added extra labor polishing the journals before to remove the sharp machining journal surfaces then after the case hardening process plus added vinyl tubing protecting these journals then used fine bead blasting at a low pressure to clean off the dark knurling color from the case hardening process.
Hope this helps.
BTW; I wouldn't get all hung up on roller speed differences for the crush as the MM knurling is rather agressive they go to a sharp point not just hash marks on the rollers like a shallow knurling job.
My take on this with different roller speeds you'll be making a shredding machine with more flour and grain damage vs cracking and crushing the grain. JMO.
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