The shaft on my grain mill is slowly getting buggered up
Yfh4orh (7.39 KB)
(grain mill shaft - Album on Imgur) from the drill chuck periodically slipping. Anyone know if there’s an adapter of sorts that is similar to the way the handle locks on with the set screw, but has a 3/8" hex/shaft or something on the other end for a drill chuck? I’d rather bugger up an adapter than the drive shaft for the mill.
Use a file to deburr the shaft of your mill. After that, make sure the chuck is very tight.
+1 ^
If your drill is scaring the shaft of your mill, it’s most likely because the chuck is not tight enough or something hard is getting lodged in the rollers. Clean up the shaft with a file as Bob suggests.
Emory Cloth really helps when cleaning up a shaft too. Files make quick work of the really rough spots but Emory Cloth smooths it all out more easily.
Paul
I had that problem frequently, even when using a pair of pliers on the chuck key to get reeeeeealy tight. The shaft on my mill has one flat side, I eventually got a file and filed two more flat sides as close to evenly spaced as possible - no more slipping and much smoother operation as with only one flat the whole thing was out of balance.
My drill is probably crappy. It doesn’t have a chuck key but tightens by hand. I don’t think it’s really intended for use with cylindrical arbors. All the bits that came with it have a hex shank like you fashioned. I ordered what appears to be a 3/8" extension with a couple of set screws on the end: Amazon.com
This is one of the most useful of the bells and whistles on the Monster Mill I just upgraded to - there are three flat sections on the shaft that your drill can tighten down on, which keeps it from slipping.
I eventually went with a 1/2 hp mill motor and Lovejoy spider connection on the shaft. I have been as happy with that as any upgrade I have ever made to my brewing equipment. That was done probably 8 years ago…
This is a great! Can you post a pic of your motor setup? Wondering if you just have it mounted to a table or board or what.
On another note, the extension I ordered has a .385" inside diameter. When I measured the grain mill shaft more closely it’s diameter is .393". I really don’t want to file the mill shaft down to fit (would probably work OK though) and modifying the ID of the adapter is tricky (used a drill press, vise, HSS drill, lube and super slow spindle speed). Out of the box, the extension won’t fit the mill shaft though. So be aware of this if anyone is finding this post at a later date.
Here’s the mounting on a table….
You can’t find a larger size?
I eventually went with a 1/2 hp mill motor and Lovejoy spider connection on the shaft. I have been as happy with that as any upgrade I have ever made to my brewing equipment. That was done probably 8 years ago…
I replaced my, poorly operating, old mill with a Monster Mill and this motor, and agree with ynotbrusum, it is a valued part of my brewroom. I consider it one of those “buy once, cry once” purchases. There have been zero problems, and that’s a huge improvement from what I had before.
Brewbama is right, it is “big enough.” 
Nah, it’s an extension for a Forstner bit. I suppose the shanks on those are ground to 3/8" (or maybe 1/2" on larger diameters) so they add a little wiggle room on the ID of the extension. I’m kind of surpised they used 25/64" on the mill shaft but it’s probably like that to fit a standard motor coupling.
Whoops, never mind my previous post. I thought Brewbama was making a joke about the size of the motor.