Motorized Grain Mill - Drive Shaft Questions

I have 1) Monster Mill with a 1/2" drive shaft, not keywayed but with three flattened sides 2) a motor with 1/2" drive shaft, not keywayed but with a single flattened side and 3) a gear box (reducer) with (a) a 1/2" female input, slotted for a keyway and (b) an output 1/2" drive shaft with a keyway.

Two questions:

1) What is the best way to connect the drive shaft on the mill and drive shaft on the gear box? I was under the impression a coupler was only necessary when the two shafts were a different diameter but I don't know it would work otherwise. Both shafts on the gear box and on the mill do not appear to be removable.

2) When I insert motor shaft into the female slotted input (bow chica wow wow), the shaft slips. If I firmly press the motor and shaft into each other, the shaft does not slip, but I'm afraid any amount of friction from the mill will result in slippage. How do I get the shaft to grasp the slot better?

Uh, Duct Tape?

So you have a not so simple problem.

The Monster Mill's shaft is designed for a 1/2" drill chuck, not a standard Keyed coupling. you will need to find a Shaft coupling that will be able to clamp on that shaft securely enough to handle the torque. A simple setscrew coupling might not be enough, might need a clamping style.

The gear box input sounds like a standard "C face" motor mount, were the keyed motor shaft slides directly into the gearbox and the motor bolts directly to the gearbox. But your motor is a "D Shaft", those do not have a the "C Face" mount, they are usually a foot mount. you will need to figure out a way to adapt the two.

Post some pics and i can help you out more.

lazybean said:

Post some pics and i can help you out more.

Click to expand...

None of my problems are ever simple! Here's some pics. I don't mind spending a couple bucks to get it working.

Mill:



Gearbox - You're right. It's made to be mounted to a different motor. I didn't spend a ton on it, so it's not a huge deal if it doesn't work out. I'll just by a pulley system if it's easier:





Motor:



Thanks for your help.

* Totally drunk taking these pictures and writing this post. I can not be held responsible for any inaccuracies.

I think you are trying to put the drive shaft of the mill into where the motor is supposed to go. That's the higher speed part and the male shaft is the speed reduced/torque enhanced part.

Think you'll have to mount a motor onto the female shaft part and get a coupler to connect the two male shafts, gearbox and mill.

{Edit: I think I read the OP wrong this mornin... sorry..scratch that}

And re: the set screw thing posted before. One of the flats on the shaft on your MM will need to be widened (with a metal file) to about twice it's width to accommodate a set screw, but it will work. Mine is working great after doing this. I chewed up the shaft with the set screw quite a bit before doing that though. That's MMs recommended fix. He says 'the shafts really are made for drill chucks, not set screws' and doing this easily corrects the issue.

Your motor isn't the same kind of mount as the gearbox, IMO. That might be hard.

The only way that I can think of for coupling this uses two complete couplings and a small customized shaft.

Couplings are used not only to connect different size shafts, but to account for a small mis-alignment between the shafts.

I would have a local machine shop cut a piece of 1/2" round stock to fit in the gearbox input shaft and put a keyway in it to match the one in the gearbox. Then use a coupling from motor to new shaft, and a coupling from gearbox output to the mill. Most of the half couplings that I have seen have both a keyslot cut in them and one or two set screws, so you can clamp on the motor flat and the mill shaft flat while using keys to couple to the gearbox.

It shouldn't be too hard to find a small machine shop that can cut a keyway.

That is the exact type gearbox i thought. A clamp on coupling might work to connect the output shaft to your mill, make sure you order it for the EXACT size shafts.

Now for the input, it is what i thought, that gear box is made for a "C Face" motor mount. We use a TEFC motor mounted to that same type gearbox. They run 10 hours a day, covered in dust, rain and fog and last for years. so if you do go that route, be assured it will last a long time.

What about a lovejoy? DO they make one with 3 flats??