Slowing down a motor.

Hi There,
You’d need to gear it down by running the motor via pulleys to slow it down. You can buy stepped pulleys that incrementally slow down a motor. It sounds like you are trying to drive the press directly from the motor.
You could get a slower motor or run through a gearbox.
A lot of presses here in the UK I’ve moved have had all manner of home made pulleys and belts to slow them down.
You could get a PWM (Pulse Width Modulator) to actually slow the motor down but this will probably remove too much torque.
There must be a machine shop near you or go online for other solutions. Good luck or alternatively get a treadle…!

you could get a 3 phase motor with a VFD. This will give you a range of control for RPMs with a dial to control speed.

Go with a treadle if you have the crank flywheel shaft. Much slower and safer for a beginner. If not then the stepped pulleys is the way to go. A very small one on motor and a very large one on the press. If you use the flywheel itself as the large pulley that works fairly well, though it adds its own set of challenges. For instance it is harder to mount a brake if the flywheel has a belt looped around it.

Learned friends are hinting at the solution but not quite going far enough. Follows:- small litho machines, Multiliths, Gesteliths Hamadas, and many more, up to Heidelberg Platens and beyond are driven with fixed speed motors running at optimum torque and power, speed governed mechanically with an almost simple, coned pulley attached to the output shaft of the motor, describing a small arc around the shaft the motor is mounted on, and controlled by a lead screw at front of machine. Not exactly high tech and working perfectly on applications as diverse as Tiny lithos, Adana T.P. 48,s Thompson Platens, Heidelberg Platens, etc etc (and the principle holds good for single phase or three phase, which is usually more complex and generally more expensive especially if artificial inverters are involved).The internet appears to be well blessed for purchasing such units, should second hand not be an option, and the prowess required, would seem to be, within first year engineering student capabilities. Re the tiny pulley on the motor and the flywheel as the big pulley, is usually unsuccessful, as the tiny pulley has so little wrap around that one would be forever using rosin or belt stick to maintain grip at the tiny pulley, or wear it out, so an alternative would be to fit a more suitable size big pulley, as an outrigger to the flywheel but only one fixed speed would be available unless a small array of slightly differing size slave pulleys were available to quick change on the motor shaft. No brake problem!!!

I have similar problem in slowing down the press. I have C&P 10x15 with 110vac, 1 phase, 1 hp, 1725 rpm, and it uses a V belt on a “Var-A-Cone VC51” pulley on the motor and goes around the 23” drive pulley on the right side. I found the varacone was set at 5” at first and press was to fast to operate. I adjusted it to the smallest pulley 1.6” and was able to get speed down to about 24 impressions per minute or about 1 per every 2.5 - 3 seconds. This is still way to fast for a beginner. After researching everywhere, I found that most folks have used a variable frequency drive to convert 110vac single phase to 208vac 3 phase and use a 3 phase motor. The other option is using a DC motor and speed controller or fixed speed AC motor with pulleys to adjust speed down to slowest speed.
I’m looking for a solution that will not cost me an additional $800 for new motor and control.

Anyone have experienced using multiple pulleys to slow down press? I currently have 1.6” motor pulley to 23” driven flat pulley on crankshaft.

Link to the “Var-A-Cone VC51” I found TB Woods:
http://www.tbwoods.com/Products_Mechanical_Variable_Drives_Motioncontrol...

I’d suggest a trip to your local well-equipped hardware store. You can get a pair of pulleys (or a step pulley), one the smallest they have and another 2 or 3 times as large in diameter, with the same size bore for the shaft and set screws, a pair of pillow blocks with the bore the same as the pulleys, and a shaft the same diameter as the bores and about 6 inches long. All that might set you back $25, probably less. Find a couple of wood blocks thick enough to raise the pillow blocks so their centers are a bit more than the radius of the large pulley off a piece of 3/4 inch plywood. Mount the pillow blocks on them, mount the pulley(s) on the shaft and install the shaft in the pillow blocks. Mount the whole assembly on the same board the motor is mounted on (but you’ll need to remount the motor with some provision for it to move closer toward or further from the fixed reducer pulley set, maybe a big hinge on a separate board with two long bolts on the other side of the board with long compression springs under the board on the side toward the step pulleys), with a short v-belt from the variable motor pulley to the large pulley on the shaft, and the belt to the press on the small pulley. You now have a 3:1 reduction in speed, which you can vary with the variable pulley, and which at its slowest would be about 8 impressions per minute.

Bob

The local farm/fleet should have all the bits indicated above.

Thanks Bob, I’ll be looking at building this reduction pulley setup this weekend. I was thinking of doing this but was wondering if anyone else had done it or seen a setup. I’ll try capturing the build and post results later.