OT: Why would anybody need a stepper this slow???

[Scatterplot]

http://cgi.ebay.com/Crouzet-Synchron...QQcmdZViewItem

21 revolution per YEAR stepper motor!!!

[mark61]

So that the house you build can ALWAYS be syncronized/ and oriented with Jupiter and the planat Urainus!

mark61

[Swarf&Sparks]

They're not steppers, they're synchronous motors.
Hey, you could build an orrery

[Evan]

The stepper drive on my scope only runs about 15 steps per second.

[DR]

"The stepper drive on my scope only runs about 15 steps per second."



Hmmm....this brings up a question. I'm working on a very slowly rotating device driven 1:1 with a 200 steps/rev motor. At how slow a stepping rate do you suppose the motor ceases to have smooth motion, but more of noticeable ratcheting motion?

[Weston Bye]

My article, The Quartz Movement, in the Digital Machinist was about this:

Electronics and mechanics to produce 1 RPM. Perfect for driving a second hand on a clock. The rest of the clock will appear in the next issue of the Digital Machinist.

The rotor moves in distinct 1 second steps.

[Todd Tolhurst]

Smooth motion to the naked eye? Probably right about 15 steps/second. Film or video (or flip books!) frame rates slower than this are perceived as jerky.

[Optics Curmudgeon]

Film is 24 frames per second, video is 30 (in the US).

Joe

[Weston Bye]

The 8mm film format was available in 24 fps for professional work, but far more popular was the 18 fps for amateur/home movies.

[ptjw7uk]

These motors were used in process control before the integrated circuit solid state timer became more widely available.
I used to use a 1 rev per 24hrs to control a liquid nitrogen supply for amass spectrometer. I believe there were 14 day per rev motors used in heating controllers in public buildings again now superceeded by solid state.
The Crouzet were a simple cheap solution and would last several years before needing replacement.
Peter