Any machinists here want to help me out?

[Jo3sh]

So I want to tighten up the gap on my mill. The mill works great, but it's already at its tightest setting, and I think there's more extract to be had, as the setting is pretty conservative. My mill adjusts by means of eccentric bushings for the idler roller.

Several ideas have occurred to me - any one would improve my mill:

-- Make new end plates for my mill, with the holes the roller axles turn in a touch closer together. I assume this would mean new oil-impregnated bronze bushings would be needed as well.

-- Make a new idler roller with a slightly larger diameter.

-- Make new eccentric bushings with a higher degree of eccentricity - that it, the thin bit would be thinner and the thick bit thicker.

Is there anyone here who can help me decide on and implement a solution? If you're in Southern California, that would be excellent, but the mill head can obviously be shipped anywhere. Obviously, if it's just cheaper to buy a new mill, I might as well do that, so budget is a concern although not an overriding one.

 

[WBC]

I'm a tool and die maker and retired. Check the bushing wear. The way you are talking, it is an older mill? The bushings can be purchased and replaced. They are usually pressed into the end plates and are just a standard size for your shaft size. Mc Master.com has the bushings as well as the mill MFG. What brand and model is it.

 

[HenryHill]

First, stick some feeler gage in between the rollers and tell us how wide the opening is. Check both ends. Guessing that this is a two roller mill...what brand/model, or maybe just a pic?

Second, what IS your efficiency now?

 

[Jo3sh]

The mill in question is a BrewTek Malt Mill. It is in fact a two-roller mill. I bought it probably ten years ago at Brewer's Resource in Camarillo, CA, which is sadly no longer in business. While it does have some miles on it, I did just have it apart, and I did not see any wear in the bronze bushings, not is there any noticable play in the rollers.

I don't have it in front of my as it's currently at by brewing partner's house, but I seem to recall that the tightest the gap can get is between .035" and .040". My current efficiency is about 70-75%; last batch was 71%.

At the time I bought it, I don't believe the Barley Crusher or the Crank & Stein were on the market - the big movers in the homebrew mill market were the Valley Mill and the Schmidling malt mill - I think Phil Listermann had just come out with the PhilMill.

EDIT:
Here are a couple of pictures of the mill in its present form:

 

[Bobby_M]

I think your gap is fine. Maybe you ought to look to a few other factors in increasing your efficiency. Batch or fly sparge? Do you get your mash up to 165-170F during the sparge? If batch, do you do it via one or two infusions?

 

[the_bird]

How long does it take to run the malt through the crusher? You could always try double-crushing it, as well. But, I'm with Bobby; look into other factors first (like pH).

 

[FSR402]

I'm with them. The .035 gap is tight and I would be scared to go much under that for a stuck sparge. I would look into other ways like the sparge, mash PH and temps.

 

[Jo3sh]

I do need to check my gap, but you guys are probably right that there are other places to look. pH should be fine as my water's not way out of whack and I use 5.2 buffer salts, but I should get some papers and check it out to be sure.

In answer to the bird's question, the motor turns at 173 RPM, and the mill pulls about 3 pounds a minute through the gap.

 

[HenryHill]

What brand of motor is that?

The mill is probably doing what it should/can do-lot to be said for longer rollers and through-put, but what it does process is probably fine and gains to made will be in squeezing out the sugars through temp and solubility-as in double sparge after mash with mash-out type water temps, and not in squashing them grains more.

Motor speed is near optimum-I think fast (300 and above) is not really your friend. Interesting and braggable, but not necessarily your friend, as in a controlled, consistent output product .

 

[Jo3sh]

What brand of motor is that?

The label says GEC Machines, Liverpool. I bought it used, then added the spider couplers, etc.