Stepper motors from dead printers

[avandonk]

Had a morning of extracting stepper motors from some dead printers
I have been collecting.Also some servo motors.Here's a couple of pics.

Bert

[asimov (John)]

Yes, they do come in handy eventually dont they...I have a box full of them that came out of old electric typewriters (my EQ mount is driven by one) & various other motors from all sorts of equipment.

[davidpretorius]

some good stuff there, the 1.8 degree 5 or 6 wire bipolar are the best i reckon. I have one that is driving my focus with no gear reduction and i have more than enough step range to focus with.

[rmcpb (Rob)]

How do you go about controlling one of those motors??

[davidpretorius]

a stepper motor controller from dse or rscomponents. i have bought a $85 usb version as that is friendly for my computer. I can control up to three motors off this board by sending signals to the board from my computer.

http://www.ar.com.au/~softmark/page44.html

[ving (David)]

fair enough... you could drive a dob with those couldnt you?
if only I had the knowhow (and time)

[rmcpb (Rob)]

Is there a simple way to control these motors without the need to have a laptop on hand?

[avandonk]

Dave how is the speed detemined with that USB controller is it set in software or is it as shown, slow med fast?
I have got a parallel port driven controller and was thinking of getting the USB version you refered to.

Bert

[davidpretorius]

yup,


you have to gear down the ratio as these things will step one whole step at 1.8 degrees and half step at .9 degree. this is too much as the earth is rotatinig slower than that. You basically need it to step at least 15 times a second so that you can do deep space photography.

roughly 24000:1

I am buying gary beals to have a play with and then working with mick pinner to get a locally made version up and running for next year.

You want to be able to make it real easy for people to fit to their dobs for tracking and goto etc

[avandonk]

Originally Posted by rmcpb

Is there a simple way to control these motors without the need to have a laptop on hand?

There is use a crystal timer or LM555 timer chip plus stepper chip.Lots of stuff on internet.

Jaycar have a book for about $15 dollars on steppers and their control,getting it today.

Bert

[davidpretorius]

Originally Posted by avandonk

Dave how is the speed detemined with that USB controller is it set in software or is it as shown, slow med fast?
I have got a parallel port driven controller and was thinking of getting the USB version you refered to.

Bert

software, so you determine what slow medium and fast is.

there would be a limit in terms of recovery time from the preceeding pulse saying "step" to the motor, but you can get your software to pulse once a second, 1000 times a second. it is up to how you write the software.

with the usb one, you get that little program as shown. if you can program in visual basic , visual c# etc, then you can add a little active x component to your code to interface quite easily to it.

If you have no idea what i just said, i would be more than happy to write some code for you cos of all your kind and generous gestures!

what do you have in mind for the stepper motors?

[avandonk]

Here's the worm thats going to drive the worm on ballaratdragons mount.

150:1 and 240:1 ratio is 150x240= 36,000:1 should be smooth enough.

Bert

[avandonk]

Thanks Dave I will order a couple.The problem with the parallel port controller is that I have to switch between it and the parallel port relay box for autoguiding.

Bert

[davidpretorius]

these pictures are what i have bought from gary.


it is not laptop linked, i intend to make it that way, but this is wht mel bartels has been working on for a long time

http://www.bbastrodesigns.com/

[davidpretorius]

Originally Posted by avandonk

Thanks Dave I will order a couple.The problem with the parallel port controller is that I have to switch between it and the parallel port relay box for autoguiding.

Bert

yes exactly!!! - parrallel ports and com ports are all full with other stuff, whereas you can expand your usb ports

do you need 2??

each card has three motor controllers

[avandonk]

Yes dave need two, one for me and one for kens mount so he can use the long exposure mod of the ToUcam on the parallel port.

Bert

[davidpretorius]

Originally Posted by avandonk

Here's the worm thats going to drive the worm on ballaratdragons mount.

150:1 and 240:1 ratio is 150x240= 36,000:1 should be smooth enough.

Bert

that looks like a 4 wire unipolar stepper, so you need to use 1 1/2 of the three controller ports. I was just talking to the manufacturer not two days ago re this. I will ask him exactly how you program the software to pulse it.

i am just digging up my notes and calcs on this................

[avandonk]

I have got more steppers see pic at start of thread.The biggest motor in the middle is six wire the others are five.I was thinking of using the six wire for Kens RA drive.I'll have to check the step size it looks like a double layer it is 7.5 deg. ie 48 steps per rev. just counted them.Shoud be able to half step it.
What I want it for is to build a stepper focusser for the new manual 300mm F2.8
Fluorite by just running a toothed belt around the focussing ring on the lens.

Bert

[davidpretorius]

Originally Posted by avandonk

I have got more steppers see pic at start of thread.The biggest motor in the middle is six wire the others are five.I was thinking of using the six wire for Kens RA drive.I'll have to check the step size it looks like a double layer it is 7.5 deg. ie 48 steps per rev. just counted them.Shoud be able to half step it.
What I want it for is to build a stepper focusser for the new manual 300mm F2.8
Fluorite by just running a toothed belt around the focussing ring on the lens.

Bert

.25 arcsec to 1 arcsec is the suggested step sizes for smooth transition during imaging.

therefore 3.75 degree half step needs a 54000:1 for .25 arcsec, and 13500:1 for 1 arcsec movement.



for focusser where i have directly coupled it, at .9 degrees in 1/2 step mode, i get about 7-10 odd steps where the focus hardly changes due to seeing etc.

so you would only need to gear down at 4:1 or 5:1 to get that .9 step and your focusser will be nice and fine, but not too fine!!!

[avandonk]

So 36,000:1 meets with your aproval Dave? ...Dave?

Bert