Advice for adjustable roller mill project.

[BadWolfOregon]

I'm working on finalizing my design for a grain mill that I will be making on the cheap thanks to a workplace that supports personal projects, lets me pick scrap at scrap cost, and has many willing machinists.

My major sticking point right now is how to make the idle roller adjustable. I know the commercial mills use eccentric bushings, but a lot of my "experts" are suggesting some sort of thumbscrew sliding bearing deal.

Anyone have any additional advice for simply construction and use?

Thanks!

 

[JLeuck64]

Awesome username!

 

[IslandLizard]

Do a search in the DIY section on mills. Quite a few nifty projects there, some are very detailed.

They typically use adjustable eccentric bearings/bushings that can be locked. Maximum gap size used (between the tops of the knurls) is typically 0.045" where 0.060" is about the upper limit. Many batch sparging or BIAB homebrewers mill at around 0.034" (credit card) or even a bit tighter. The minimum can be around 0.010" for really small grain, like Triticale or buckwheat groats.

If you really want to get into it, adding a calibrated gap scale would be great. I mill Barley at 0.032", and small kernel malts like wheat, rye, and flaked goods at 0.026", so I usually need to adjust at least once per milling session.

Look at pictures of the Monster Mill and Crankenstein and see how they use different adjusters.

How would a sliding bearing work?

If I were to design a mill I'd go for 2" hardened steel rollers, 6-8" wide and a 1/2" drive shaft. Use a 1-1.5 hp 1750 rpm gear motor with a 10:1 reducer. Or one of those low voltage ones which can have huge torque. Here's a thread on low cost motorized grain mills.

 

[BadWolfOregon]

Great advice, thanks! I'll check out more threads.