My Malt Mill Build

Thought I'd post a few pictures of the malt mill that I designed and had built by a friend of mine. I think it turned out very well and I'm happy with my design. Just wondering what others think.

The mill specs are:
ø2-5/8" diameter x 8" long stainless rollers
Gap adjustable from 0.010-0.075 in 0.005 increments
6205 roller bearings

wow. Purdy.

Do you have any more pics?

id love some cad or cnc files on this

Great build. What sort of mechanism is that for the gap adjustment? Is that a spring loaded ball bearing that is pressed into the holes or do you uses those as a seat for a set screw?

The gap between the rollers is adjustable because the bearings for the second roller are each mounted in an eccentric (one of them is shown in the second picture, the other is a mirror image of this part). As the eccentric is rotated the gap is adjusted from 0.010" to 0.075" (if I remember correctly).

The ball-nosed spring plunger isn't pressed in, it's threaded into the back of the bearing block just like a set screw. The ball nosed end seats in the dimples that are machined into the eccentric (see the second pic). This causes the eccentrics to "click" and "lock" in place at each dimple location.

I believe this is the same mechanism/design used in monster and crankenstein mills. The main difference between their designs and mine (apart from the roller bearings) is that I wanted even 0.005" adjustments throughout the adjustment range. This is why the dimples in the eccentric are not evenly spaced (as an eccentric is turned the angle needed for a 0.005" adjustment changes).

I do not have any other pics of the mill at this time. I was excited to put it together and forgot to take pictures of the assembly (which is why I used screenshots of the CAD model). I'll probably disassemble the mill at some point, when I do I take some more pictures.

One other thing: the guy who machined the parts for me was asking about the possibility of building a few more of these mills to sell and make a few bucks. I wasn't sure if there'd be any interest but told him I'd ask around.

I was able to scavange most of the material for my mill so I'm not sure how much it'd cost to build one with new material (the stainless for the rolls wouldn't be cheap, switching the rolls to mild steel would lower the cost significantly I'd think).

Anyway, any comments? If interested what do you think a fair price for a mill like this would be? If there is enough interest and everyone can agree on a fair price I'll see if/when he'd be able to build more.

Count me in for interest. I'd also like to see a keyed shaft to mate a motor to, and a gear option (or extended shaft to place gears onto). My current mill jams too often.

It's a little hard to see in the pics but the driven shaft is keyed.

I originally intended to drive both rolls. One of my early designs was driven via toothed pulleys and a serpentine belt. A geared system might also work but keep in mind that the backlash would change every time you changed the gap between the rolls (might not be a big deal with this small adjustment).

Personally I think the advantage of driving both rolls (if there is an advantage) is more than outweighed by the additional complexity required. For simplicity I decided to stick with one drive roll, directly driven by a gearmotor.

Edit: I just noticed that you said your mill jams too often. Do you believe this to be because of the single driven roll? I'd think it is more likely due to an underpowered mill (no offense intended). What are you currently driving it with?

Yavid, what are you driving yours with?

If I remember correctly it's a 1/2 HP motor with a 40:1 reduction. It was salvaged from a pallet wrapper (it was the motor that spun the pallets). It runs at about 1/2 the speed I'd like but has a boat-load of torque. I'm pretty sure this thing will crush anything or break itself trying.

I was a bit concerned about the speed at first but not so much anymore. Takes 45 minutes to get my mash water to temp anyway.

Also, if my assumption that surface speed is proportional to the amount of grain a mill will process in a given amount of time then my mill should keep up to a base model monster mill being turned by hand (~90rpm).

The formula I used: roll diameter * pi * length * rpm = sq in/minute

monster mill turned by hand: ø1.5" * pi * 6" * 90rpm = 2545 sq in/min
my mill: ø2.625" * pi * 8" * ~40rpm = ~2640 sq in/min

Yavid said:

One other thing: the guy who machined the parts for me was asking about the possibility of building a few more of these mills to sell and make a few bucks. I wasn't sure if there'd be any interest but told him I'd ask around.

I was able to scavange most of the material for my mill so I'm not sure how much it'd cost to build one with new material (the stainless for the rolls wouldn't be cheap, switching the rolls to mild steel would lower the cost significantly I'd think).

Anyway, any comments? If interested what do you think a fair price for a mill like this would be? If there is enough interest and everyone can agree on a fair price I'll see if/when he'd be able to build more.

Click to expand...

I might be interested, depending on the price. Any idea what that would be? My son is a machinist, but doesn't seem to have any interest in making me a mill.

any chance you would be willing to share the plans? my friend owns a machine shop, and id love to have him build me one

Would you mind to provide me some pics or explain how does the roller connects to the bushing without touching the aluminum wall?
It also seems the bushing is not glued to the wall, is it?
I'm also interested in understand how the gap adjustment works.
Thanks

I'm not on the site much anymore so I'm replying to this fairly late. Like almost a year late.

There aren't any bushing in this malt mill so I assume you're asking about the roller bearings:

The bearings for the fixed roller are pressed into the aluminum side plate until the outer bearing race makes contact with the shoulder. If you look at the 3rd picture on the first page you can see the shoulder on the smaller of the two holes.

The bearings for the adjustable roller are pressed into the eccentric in the same way. The eccentric is then inserted into the side plate and held in place with a snap ring. This can be seen in the 4th picture.

There is no glue holding the bearings; they're just press-fit into the side plates and the eccentrics.

The rollers both have a shoulder that contacts the inner bearing race. This is what keeps the roller from contacting the aluminum side plate. You can see the gap between the roller and the side in the last picture.

The gap adjustment works because the eccentrics that hold the bearing aren't pressed in place and can be turned. The center-line of the roll isn't the same as the center-line of the eccentric so as the eccentric is turned the roll moves back and forth (actually it also moves up and down because it is rotating in a circular pattern).

There is a ball nosed spring plunger threaded into the back of the side plates. The hole for this can be seen in the 4th picture. The spring plunger has a little ball on a spring that "catches" in the little dimples on the eccentric as it is turned. This is what holds the roll in position and keeps it from moving when the mill is being used.

Make sense?