I've been milling grain using a DeWalt handheld 20 volt drill since I purchased my Cereal Killer grain mill from Adventures in Homebrewing last year. It isn't terribly inconvenient, but since I brew alone it gets dicey pouring grain while manning the drill at times. I started shopping for a motor and found a Maytag washing machine motor from I'm guessing the 1960s for $25. When I plugged it in for the first time I was amazed at how smooth and quiet it ran.
I crunched the numbers with some help from online calculators and found that in order to slow down the 1725 rpms of the motor to around 200 rpm I'd need either a 12 or 14 inch drive sheave for the mill. The smallest diameter sheave I could find for the ½” bore of the motor was 1-½”. I picked up a 12” sheave on eBay for $44 and a 1-½” sheave from Grainger for $10. I also picked up an adapter for a ⅜” bore shaft to fit a ½” bore sheave. Regrettably, I measured my drive shaft to be ⅜”. Only after the fact did I look up the specs to my Cereal Killer mill and find that the shaft is actually 10mm. That is about .394” as opposed to the .375” I mistakenly measured. So the ⅜” to ½” bore adapter didn't quite fit on the mill's shaft. A metal file and some elbow grease helped me shave off about .02” so the adapter would fit.
Next I started building a station to mount the mill and motor. I found a convenient spot between some shelving and my deep freeze, near my basement brewing setup. I decided it would be nice for it to be on drawer slides so it could be tucked away when not being used and pulled out to place a bucket underneath when milling.
Not knowing a lot about the motor, I hoped I could reverse the polarity to throw the mill in reverse if needed so I picked up a double pole, double throw switch. When I powered it on, despite triple checking the wiring, it unfortunately only goes one way. If I ever get a stuck mill I'll have to turn it off and reverse by hand. Haven't had that problem yet with using a drill so I don't anticipate this happening much if at all.
All in all it was a fun project. Not including the cost of the mill I've got $172 in it which includes the motor, sheaves, belt (I picked up a linked belt from Harbor Freight for $33 which I already like a lot), some lumber and other miscellaneous hardware. For anyone who has a Cereal Killer mill wanting to motorize it be prepared to do some minor metal work unless there's a 10mm to ½” adapter available somewhere that I didn't find in my fairly extensive research.
