Stepper motor speed control connections

Thinking of replacing the mill table feed on my Dore Westbury with a stepper motor fed using one of the Pwm speed control units from eBay etc.

I am thinking in terms of a nema23 motor with a quimat 6600 driver with a direct connection to the feed screw.

I see how the motor connects and sets up, but am not sure of the connections from the speed control module to the driver are made.

Has anyone used this set up or knows how to connect it.

Ian

The drier module will have two key inputs - step and direction. You need a simple pulse generator not a PWM unit like this **LINK**

First I suggest you spend a month or two learning about simple electronics and stepper motors.from the sort of articles on the 'net written for robotics beginners.

Thanks for your suggestion Bazyle, I am not unaware of electronics, and want to use a readily available module with a rotary speed controler.

I spent most of my working life in the electricity supply industry, and know the pitfalls of wrong connections, that is why after spending time researching the web and not finding the relevant details I asked for help, not sarcasm.

The driver you refer to for your stepper motor requires a direction signal, 0 or 5V probably, the enable input probably needs 5V to make it run and pulses on the input marked pul. These pulses can be supplied by a pulse generator of the type Bazyle has linked to. It will probably want the frequency control pot removing ftom the board and replacing with a wired standard pot to make speed change easier.

A toggle switch to put 5V on or off to the enable connection will be your start/stop switch.

A toggle switch to put 5V on or off to the direction conection will select left/right.

The jumpers on the board will select the speed range that suits your setup and the wired pot will give you control of the speed.

You may need pull down resistors on the inputs. The driver should be supplied with wiring details.

Martin C

Using a stepper as a power feed was covered in a You Tube video by Myfordboy.

This https://www.ebay.co.uk/itm/12V-24V-Stepper-Motor-Driver-Controller-PWM-Pulse-Signal-Generator-Speed-Control/273138644554?epid=858678324&hash=item3f9854f64a:g:0ZgAAOSwXXpawc4Z may be right up your street.

.

This should help, Ian : **LINK**

https://m.youtube.com/watch?v=JjbCv3EOp7M

MichaelG.

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Edit: also this, regarding use of pulse generator: https://m.youtube.com/watch?v=AnrD3Q3Hd3I

Edited By Michael Gilligan on 04/09/2018 07:18:11

A slightly off the wall thought, you could consider using a Ward division controller to generate the pulses. That allows you to set speed and direction but also program increments which could be useful in drilling rows of holes. It has a mode IIRC (I'd have to remind myself by having a play with mine) where you can get it to drive for a given distance at a set speed - kind of electronic table stops.

Stepper motor drive seems to be a fairly expensive alternative, unless anticipating fancy computer control later.

A DC motor seems, to me, to offer an equivalent power feed opportunity at a rather lower entry cost as this type of motor is easily sourced from a motor vehicle. Relatively low tech, but effective.

Small 3 phase drives with a VFD are likely another competing technology. Mine has a 415V motor which has had a VFD added and works perfectly adequately.

Ian,

The second video MichaelG indicated should get you on track very quickly.

Some sums for feed rates and stepper sizing..

A NEMA23 directly coupled might be a little small for your application - I am not sure of the friction/stiction of the slide on the Wesbury.

A stepper tends to lose torque when half-steps or micro-stepping is applied, and also loses torque rapidly as RPM increases, so you have some conflicting requirements between smooth feed, stepper RPM, and small enough feed steps.

Assume the leadscrew pitch is say 0.1inch - then if the stepper runs in full step mode,ie 200 steps/rev, each step is approx 5 thou (0.0005inch), which is fine. Now to feed at say 20thou per second, that is 4 steps/second. At such a low step rate the motor growls and the feed is not so smooth - you will feel the mill table vibration. That may make the finish a little less than great..

At 0.1inch per second feed the stepper runs at 20 steps/second - it is happier there, but still a very low step rate, and still vibrates - 20Hz is still a low frequncy and vibration will still be evident. Remember, the stepper in effect , stops 'dead' after each step - there is mechanical inertia that helps it not stop quite dead, but it vibrates. Also, 0.1inch per sec feed is rather fast for anything other than plastic and maybe light aluminium cuts on the Westbury?

Basically, the stepper is working uncomfortably at its bottom end. The vibration can be smoothed out almost completely by increasing the number of electronic steps per motor full step, ie, half, 1/4,1/8 stepping, etc. The motor will be much smoother and vibration less or none. However, the motor loses torque considerably, and may miss-step or stall. 1/2 step still has good usable torque so may work better.

A better way is to gear the motor to leadscrew drive - say 4:1. The motor then does 4 turns for one leadscrew turn, giving 16 steps/sec for a 5thou/sec feedrate, and halfstep increases that to 32steps/sec, much better. The torque is also increased by the gearing, so a Nema23 will do the job.

At 0.1inch/sec feed rate, the stepper spins at 4RPS = 460RPM which is comfortable.

Sorry for the long speech...

Joe

edit - just to add - alignment is always an issue when trying to direct direct couple the motor shaft to leadscrew - either use a flexi-coupling, or a toothed belt and pulley arrangement, through which the gear ratio can easily be applied.

2nd edit: Or use a NEMA34 motor,direct couple, and run in 1/4 or 1/8 step mode. Also try to use as high a supply voltage as the stepper driver will allow - the voltage is what overcomes the motor back-emf and helps prevent stalling

3rd Edit!!!   - In the Myfordboy video below, it appears a NEMA34 motor is used- BUT, it is a double stack motoriie, twice the length of a base motor, so does provide more torque as well.

Edited By Joseph Noci 1 on 04/09/2018 09:05:42

Edited By Joseph Noci 1 on 04/09/2018 09:08:46

Edited By Joseph Noci 1 on 04/09/2018 09:12:40

This is the Myfordboy video John Reese mentioned. I think this the type of control you are looking for.

Actually, the motor in that video is a NEMA23, double stack motor, not NEMA34 as I first said - I meant 23...

The double stack motor does give more torque, and would do fine for your application - it is just twice as long.

Joe

My simple totally unsophisticated power cross feed consists of an up/down car window motor, these motors are designed to rotate in both directions unlike some windscreen wiper motors. For speed control I used a small circuit published in Model Engineer 21st September 1990, so by reckoning its worked without failure for 27 years and all the electronic components we were pre-used. John

Thanks for your constructive replies, the Myfordboy video is the one that I first saw, but the wiring between the components was not given.

My mill uses a small geared dc motor at present as shown in Mike Weeblys site, but it is a small motor and can be a bit under powered.

Motor length would not be a problem Joe, and thanks for the run through on torque etc, appreciated.

It was just the connections shown in the video are not clear via the screen shots, and I wanted clarification.

Mmmm,

At 0.1inch/sec feed rate, the stepper spins at 4RPS = 460RPM which is comfortable.

Seems a 4th edit was required..4RPS = 240RPM, not 460RPM...Fingers ahead of brain..again...

But the stepper is very happy at 240RPM..

Joe

Ian, PM sent. Check your inbox.

Quick update, I have ordered the parts on Myfordboys video and am being sent the connection details that I needed.

Apparently the speed controllers do not have any connection details supplied with them, as a few of the people who purchased them commented on in their reviews.

A lot easier than trying "suck it and see" with easily fried components if you have the relevant connection details to hand.

Once again thanks for all the help offered, much appreciated, I will post on how I get on when the parts arrive and I have fitted them.

Ian

..and the wiring details please for any more followers-on (or is that follower-ons?)

pgk

Ian and pgk

The wiring details are given in a link provided in the Youtube video write-up, just scroll to the bottom.

Emgee

http://myfordboy.blogspot.com/p/stepper-motor.html

Edited By Emgee on 04/09/2018 12:16:40

2nd edit replaced link

Edited By Emgee on 04/09/2018 12:19:13

I used one of these when I added a power raise/lower to my Warco GH universal mill.

**LINK**