Power two machines with one motor

[SteveM]

I have my Pratt & Whitney 3C mill. It's on a bench with a bad variable speed setup that doesn't have much variation.

Last year, I had a shot at a 3C lathe, so I grabbed that.

Also got a good deal on a 3/4 hp reeves drive - not the same model that P&W used, but usable nonetheless.

So I have one really good motor / transmissions and two machines.

I'll never use both machines at the same time, so I figured mount both to the same bench, locate the drive unit underneath and rig up some pulley / shaft system to drive both, but being able to drive one at a time.

I guess it's an undermounted version of a line shaft.

Anyone done this and what's the best way to switch the power from one to the other?

Steve

[Rich_Carlstedt]

Steve, When I visited England to attend the ME show a number of years ago, I happened to be invited to a British Gentleman's shop which
was a garden shed and only maybe 5 feet x 8 feet or so and he had one motor and it drove his ( small) Lathe, Mill, and drill press- one at a time.
The motor powered a telescopic square tube (within a square tube ) and it had U Joints at the motor end and the working end. He had a pin that could be pulled ( Rapidly) to disconnect the U joint to fit on the next tool. He had a pull chain hanging from the ceiling to power the motor on and off and it could be reached from anywhere.
Needless to say, you did not walk around the shop when the shaft was turning , but worked as long as you stayed in front of the machine being powered.
He had to duck under the shaft at times to get things. It was a one man shop
His workmanship was superb.
Rich

[RMinMN]

Male the line shaft as you propose with a quick belt tensioner on each machine. When you finish with one, loosen the belt and perhaps even flip it off the drive pulley. Put the belt back on the next machine and re-tension it.

[John Hasler]

Good idea. You could even rig a three-position lever to control the tensioners: lathe-neutral-mill.

[liveaboard]

Those setups were the norm once; I've been to an old shop in Bombay that had it all still working, one motor to drive countless machines [that is to say, I didn't count them].
Two things; for one, those shafts and belts are a serious safety hazard.
Secondly, motors are usually cheaper than all the parts required to split the power.
In this case, maybe not. But think about it.

[SteveM]

Secondly, motors are usually cheaper than all the parts required to split the power.
In this case, maybe not. But think about it.

It's not a question of the motor, it's the whole reeves drive. Been looking for one for years and now I have ONE. I can't wait years more to buy another one. And, yes, I can buy a 3-phase motor and a VFD, but I'd have to wait until I had the money to buy one.

Got this one for $50 and it runs flawlessly. I figured out what pulleys I need to get the correct RPM range for the mill.

As to safety, all of this will be under the bench, and I'd try to enclose as much of it as I can, maybe boxing in the shafts. It's like no worse than having two motors plus countershafts and belts under there anyway.

Steve

[Mr Ron]

One concern I would have is if the motor can be reversed simply by a switch. Machines may be back-to-back abd require reversal of the motor.

[SteveM]

The motor is 3-phase, so it can be reversed.

Both machines will be in the same orientation, but when you put the right angle head on the mill, you have to throw it in reverse for it to run forwards.

Interesting wiring, which I had not thought of, that I need to send the three phase to only one of the drum switches. If they were just simple on/off switches, it wouldn't matter - if either was on, then it's on, although you would not be able to stop if from the mill if the lathe switch was on.

The drum switches are reversing (actually, they are 3-phase, two-speed reversing drum switches), so I think I would need some sort of multi-contact two-throw switch to move the power from one switch to the other. Or just run it off a central switch for on/off/reverse and then use each machine's drum switch as an on/off once the motor is running.

Steve