[Newbie] Stepper motors

[DavidR8]

I have a project where I'd like to manually control a ball screw with a stepper motor. I'm curious to know if stepper motors can be controlled with a simple switch so the motor can run forward, reverse and off.

 

[JimDawson]

No. But a controller is about $20. https://www.amazon.com/s?k=stepper+...pper+motor+c,aps,217&ref=nb_sb_ss_ts-a-p_1_15

 

[DavidR8]

Thanks @JimDawson, that looks like it will do the trick.

 

[Bi11Hudson]

A stepper motor is a completely different device from an induction motor. With a permanant magnet rotor, it can be used as a generator as well as a motor. A stepper motor, a "super-cap", and an LED make a usable low power flashlight. With a handful of other parts, of course. . . No battery, just crank and go.

A "Fwd-Off-Rev" switch can be used, but not like an induction motor. There will be a controller between the switch and the motor. Fancy, high fahlootin' electronics. . . Controllers are cheap, and provide the functions you desire. I use M.P.Jones as a source (www.mpja.com). They tend toward cheaper devices, but stuff comes and goes. If you find a particular model, it may, or may not, be available next week.

Steppers have taken over a number of low voltage or low power applications. They are even available in 120 or 240 volt applications, but very costly. The big advantage is that they can be "stepped" to make one revolution. One step at a time. . . A 7.5 degree stepper can be stepped 7-1/2 degrees, and then waits for another pulse. That pulse can come in 1/1000 of a second or it can come next week. Coupled to a "lead screw" to make a linear actuator, it can provide a highly controlled positioner. Such as replacing the hand wheel on one end of a mill. Speed and direction are easily controlled.

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[DavidR8]

Thanks gents, this is very helpful!

 

[macardoso]

Generally I've found that many applications where one would like to use a stepper motor as a speed control device would be better suited by other motors.

Steppers are great for what they are designed for - positioning, but have a lot of drawbacks. Namely: audible noise, external control electronics, poor maximum speed/speed torque curve, vibration, and cost. For a fixed speed application, a geared DC motor will often do everything you need for less cost and very low complexity. For variable speed applications, a PWM driver (very cheap) can be used with these.

I love motion control and often find myself wanting steppers or servos on everything, but honestly some of the simplest technologies are the most reliable for simple applications.

 

[DavidR8]

Thanks @macardoso, I'm thinking about building an X-axis power feed for my mill so was thinking that the ability for a stepper motor to 'lock' in position would be an asset.

 

[macardoso]

Thanks @macardoso, I'm thinking about building an X-axis power feed for my mill so was thinking that the ability for a stepper motor to 'lock' in position would be an asset.

That is good. If you do have ballscrews then you need some locking mechanism. ACME screws have plenty of friction where backdriving is not a concern.

Is this a manual mill with a ballscrew?

 

[DavidR8]

It's my RF clone with Acme lead screws.

 

[macardoso]

I wouldn’t worry about the need to lock the motor then. You’ll honestly prefer not “feeling” the motor when you spin the hand wheel.
Steppers have detent torque even when powered off and will start to back drive if you spin them too fast.