Stepper motors from dead printers - Page 2

davidpretorius · #21 29-11-2005, 04:29 PM

i am very new to this as i am yet to build one myself, but 36000:1 should be very good. at the end of the day, a 1.8 / .9 stepper could always be swapped, if the extra resolution was required

ving (David) · #22 29-11-2005, 04:31 PM

why wait till the end of the day davo?

avandonk · #23 29-11-2005, 04:32 PM

Yes thats what I thought.Thanks, if the 48 step motor is to coarse and induces unwanted movement we can always get a 1.8 deg.

Bert

avandonk · #24 30-11-2005, 07:25 PM

davidpretorius have you seen these,the top one, runs off the serial port
http://www.oceancontrols.com.au/moto...ontrollers.htm

How difficult or otherwise would they be to program.Any advice please?
I saw these some time ago I got the parallel port relay box from them.
Bert

davidpretorius · #25 30-11-2005, 08:11 PM

i personally have not played with serial ports. it mentions ascii commands. I could contact them to see how well they can be programmed in Windows if you would like?

avandonk · #26 30-11-2005, 08:31 PM

That would be great Dave thanks.

Bert

avandonk · #27 30-11-2005, 08:32 PM

That would be great,thanks Dave

Bert

Merlin66 (Ken) · #28 01-12-2005, 08:40 AM

Yes is the answer. I don't remember the IC chip #, but with a very simiple R-C 555 timer circuit you can get the steppers to drive at different rates.
I use this set up to drive a 1/2" threaded rod and a moulded arc on my 6" f3.5 Poncet mounting.

Merlin66 (Ken) · #29 01-12-2005, 08:48 AM

For focussing, it depends on the thread pitch of the focusser. Usually within 0.001" is certainly "precise" focussing. The speed of the motor/ step size should be based on this calculation. The .25 to 1 sec arc limit is usually for fine tracking ( in RA) and achieved by mini stepping the motor ie 1/10 of a step as per Bartel's drivers. I'm putting together a 1.8 deg/step stepper with a 60:1 gearbox and a final 20:1 roller drive ie 1300:1 to give fast GOTO movement at 4 deg/ sec and tracking at 0.5 sec arc.

davidpretorius · #30 01-12-2005, 10:51 AM

Quote:

Originally Posted by Merlin66

I'm putting together a 1.8 deg/step stepper with a 60:1 gearbox and a final 20:1 roller drive ie 1300:1 to give fast GOTO movement at 4 deg/ sec and tracking at 0.5 sec arc.

my dob driver arrives next week from gary in NZ (thanks gary) and i will be very interested in the mechanical setup.

That is a great range of speed. Obviously using 1/10 microsteps?? Did you source your gear locally?

Merlin66 (Ken) · #31 01-12-2005, 11:54 AM

Can't honestly remember where the motors originated, collected over the years. The 60:1 gearboxes from CBC model NRV030, the 20:1 comes from a 35mm wheel driving on a 760mm diam disk. The driver software is the Mel Bartels three motor design ( includes third stepper for field rotation)

shredder · #32 01-12-2005, 01:56 PM

Hi guys,

Writing to the serial port isn't much of a problem. I have had to do it many times on different occasions, though I should also say I write software for a living so it depends on your programming background (I have code for Java or C++ for doing this).

I also have an electronics background and would agree with Merlin66 that a 555 timer chip is a cheap and simple solution to driving a stepper motor and there are lots of examples of how to do it. Even the spec sheet has a design for doing it (from memory) and the components needed cost bugger all (and is very low on power usage).

Anyway if anyone really is keen to program the serial port let me know and I will dig up some old code for it.

Cheers

Michael

davidpretorius · #33 01-12-2005, 02:05 PM

cool, windows xp sp2 has caused some hassles talking to the serial and parallel ports by the sounds of it, so i am using the usb port with visual studio 2003 .net.

visual c sounds a lot better to talk to the hardware ie cameras and ports etc!

rmcpb (Rob) · #34 02-12-2005, 12:36 PM

Question for the whizkids --- I have been happily pulling apart a printer BUT the electronics in it are all 24V not 12 as I expected. Is there any way to use these motors in a 12V system?

Maybe a dumb question but I know diddly squat about electronics.

RAJAH235 · #35 02-12-2005, 06:25 PM

No, Rob.

L.

rmcpb (Rob) · #36 02-12-2005, 09:06 PM

Not quite the answer I wanted

Starkler (Geoff) · #37 02-12-2005, 09:35 PM

Possibly, with an H-bridge type switching circuit.

rmcpb (Rob) · #38 02-12-2005, 09:39 PM

Too hard, I'm flat out understanding serial and parallel circuits!!

ballaratdragons (Ken) · #39 02-12-2005, 09:40 PM

What about those things that work the opposite to a normal transformer. They put the voltage up instead of down? 12v in and 24v out.

avandonk · #40 02-12-2005, 11:08 PM

Quote:

Originally Posted by rmcpb

Question for the whizkids --- I have been happily pulling apart a printer BUT the electronics in it are all 24V not 12 as I expected. Is there any way to use these motors in a 12V system?

Maybe a dumb question but I know diddly squat about electronics.

Steppers do not really have a voltage rating just an upper voltage not to exceed.They can run from a wide range of voltages.The stepper controller generally controls or limits the current so the stepper motor does not overheat.Some steppers can actually draw more current when they are stopped as the coils are energized so there is a holding torque.

12V should be more than adequate for most steppers.Some controllers actually pulse the applied voltage at a higher frequency than the step pulses so a higher voltage can be used and so providing more torque.

Bert