right electric motor for this...?

He wants two revolutions per **HOUR...and gradual...so he can waive a pole up and down. ..slowly, twice over the period of an hour.

that gear ratio would be 100,000 to 1... you wont find it on the market.

Feedback via an interrupter or other pulse generator could tell

Reply to
Phil Scott
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Here is his original specification:

"the goal is to raise a pole very very slowly, about 2-3' and then lower it back down again and then back up again. every cycle should be something like 1-2 hours."

He is specifying a stroke. There is no mention of "revolutions", as this depends on how you mechanically link the pole to the motor. Add a 24"-36" leadscrew of appropriate pitch to a 1 RPM gearmotor, and you can easily get that stroke rate! Use a VFD if necessary to slow down the motor. I am just pointing out that there are options besides a stepper, and they could be less expensive when you consider the cost of a stepper motor and the drive electronics. A stepper is of advantage if you need to precisely position or make small changes. He doesn't.

Ben Miller

Reply to
Ben Miller

amazing.... truly. This has to be our final conversation Ben.... I will leave you with the notion of the crankshart, rod, wrist pin and piston. An example of a rotary / 'stroke' motion interface.

and please note once again its 2 or 3 revolutions per HOUR

Reply to
Phil Scott

No, it is 2 or 3 linear strokes per hour, for example once up and once down. You are locked into one mechanical design where strokes = revolutions, but there are others. Obviously you ignored my reference to a lead screw.

For example... How many revolutions of a 1/4-20 threaded rod would it take to move a nut 36 inches? To do that in 30 minutes (for one complete up-down cycle per hour), at what speed would you rotate the threaded rod? Can an induction gearmotor rotate at that speed?

Now couple the rod to the gearbox shaft, put limit switches at each end, attach the nut to a cable, hang his rod from the cable over a pulley, etc. Of course, in actual practice I might use a leadscrew assembly with ball bearings.

Ben Miller

Reply to
Ben Miller

For that method. But the op did not specify that method. Run a cord over a pulley at the ceiling. One end of the cord attaches to the pole. The other end attaches to a drum, with a circumference of 1/2". Rotate the drum at 1 rpM(inute). In one hour, the drum will reel in (or let out) 30" of cord, meaning the pole will travel 30".

Or drive a 16 TPI linear actuator with an 8 rpM motor. Same distance - 30" in an hour.

Ed

Reply to
ehsjr

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