stepper motor question
- Thread starter daredavel
- Start date
WOW, that's a BIG image! 
Please remove it, as many of our members are on slow connections.
I've cropped your image to just the relevant area of interest:
Does the motor have a part number, and hopefully manufacturer name written/stamped on it somewhere?
Please remove it, as many of our members are on slow connections.
I've cropped your image to just the relevant area of interest:
Does the motor have a part number, and hopefully manufacturer name written/stamped on it somewhere?
Attachments
It's odd that you are reading different resistances between pairs. That might be a challenge to figure out.
A stepper with 8 wires is kind of handy, because it (normally) can be used as either a bipolar or unipolar motor. The same can be said for unipolar motors (6 wires) as they can be used as bipolar motors once you determine which are the center taps.
Bipolar motors generally have just four wires. They are most commonly used in industry, as they are more efficient than unipolar motors. However, their drive requirements are much more complex; you need a complete H-bridge for each winding - so for a single bipolar stepper, you need at least two complete H-bridges.
For a unipolar motor, you simply supply your +V to the center tap(s) of the motor windings, and ground the ends of the motor windings in a sequence to turn the shaft.
If you can find part numbers on the motor, it will help quite a bit to figure it out.
A stepper with 8 wires is kind of handy, because it (normally) can be used as either a bipolar or unipolar motor. The same can be said for unipolar motors (6 wires) as they can be used as bipolar motors once you determine which are the center taps.
Bipolar motors generally have just four wires. They are most commonly used in industry, as they are more efficient than unipolar motors. However, their drive requirements are much more complex; you need a complete H-bridge for each winding - so for a single bipolar stepper, you need at least two complete H-bridges.
For a unipolar motor, you simply supply your +V to the center tap(s) of the motor windings, and ground the ends of the motor windings in a sequence to turn the shaft.
If you can find part numbers on the motor, it will help quite a bit to figure it out.
I found this thread:
http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1241610549
...which lead to this thread (Japanese text; translation doesn't seem to help a lot):
http://members.at.infoseek.co.jp/m_vega/telescope/qcamft/control/control.htm
At this point, I can only suggest that this motor needs to be operated as a bipolar stepper, pairing up one lower resistance winding with a higher resistance winding properly, as otherwise your steps will be uneven, and the available torque will vary between steps. This may be why the manufacturer has discontinued support for that stepper motor.
http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1241610549
...which lead to this thread (Japanese text; translation doesn't seem to help a lot):
http://members.at.infoseek.co.jp/m_vega/telescope/qcamft/control/control.htm
At this point, I can only suggest that this motor needs to be operated as a bipolar stepper, pairing up one lower resistance winding with a higher resistance winding properly, as otherwise your steps will be uneven, and the available torque will vary between steps. This may be why the manufacturer has discontinued support for that stepper motor.
russ_hensel
- Joined Jan 11, 2009
- 825
Have a look at this page:
http://www.cs.uiowa.edu/~jones/step/types.html
It explains various stepper motor types. Yours appears to be a bifilar. I suspect that there were a number of these motors that were not wound correctly.
As I suggested before, you will need to pair up a 2.2 Ohm winding with a 5.2 Ohm winding, wired in series.
The trick here will be figuring out the polarity of the windings, and the correct pair. If you get the pairs mixed up, you will have very poor (if any) performance. If you get the polarity of the windings reversed, you will also get very poor performance.
You will need two H-bridges to control the motor; one for each pair of windings wired in series.
If you really don't care about performance, you might try running it as a unipolar stepper; four of the leads going to +V, and alternately grounding the other four leads. However, you will have to limit the current to the lowest common denominator; that of the 2.2 Ohm leads.
[eta]
Just found this page (again):
http://www.luberth.com/cstep/steppers.htm
Look at the Vexta diagram #5 for bipolar, and #4 for unipolar. That's as good a place to start as any.
http://www.cs.uiowa.edu/~jones/step/types.html
It explains various stepper motor types. Yours appears to be a bifilar. I suspect that there were a number of these motors that were not wound correctly.
As I suggested before, you will need to pair up a 2.2 Ohm winding with a 5.2 Ohm winding, wired in series.
The trick here will be figuring out the polarity of the windings, and the correct pair. If you get the pairs mixed up, you will have very poor (if any) performance. If you get the polarity of the windings reversed, you will also get very poor performance.
You will need two H-bridges to control the motor; one for each pair of windings wired in series.
If you really don't care about performance, you might try running it as a unipolar stepper; four of the leads going to +V, and alternately grounding the other four leads. However, you will have to limit the current to the lowest common denominator; that of the 2.2 Ohm leads.
[eta]
Just found this page (again):
http://www.luberth.com/cstep/steppers.htm
Look at the Vexta diagram #5 for bipolar, and #4 for unipolar. That's as good a place to start as any.
