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Hello,
I bought a used owis precision linear table. It already has a (closed loop?) stepper motor attached.
It has a 9 pin d-sub connector, and I am quite unsure how to use that motor. What driver?
Unfortunately I found no markings on the stepper motor itself.
Any Idea on how to proceed?
thanks
Daniel
Hi,
are you sure its closed loop? If so then it requires an encoder, which is often an add-on extension to a stepper. Your photos don't show any such extension, in which case it may
be just an open loop stepper. If that is the case then an hour with a multimeter should sort out whats what.
Please post a couple more shots of the motor and anything attached to it.
Craig
To be honest I am not sure. Their current models are with closed loop steppers, I just assumead that heir former models would be too. But now that you say that that assumption might be wrong.Quote:
Originally Posted by joeavaerage
I am happy to post more pictures when I'm back home.
Thanks
Daniel
So, I took a few pictures.
I took the thing apart as far as I got. Unfortunately the thing connecting the stepper motor to the spindle seems to be stuck (no taking apart even when opening the relevant screws).
https://www.cnczone.com/forums/attac...d=478422&stc=1https://www.cnczone.com/forums/attac...d=478424&stc=1
If I saw correctly 6 wires are going to the stepper, and 3 are going to the 2 limit switches.
So I guess open loop stepper seems the most probable?
Thanks
Daniel
Ok, now I measured it and it is slightly weird
I just cut apart a DB9-RS232 Cable to test.
https://www.cnczone.com/forums/attac...d=478568&stc=1
(all values are in Ohm), X means no connection
Any Ideas?
Thanks
Daniel
Hi,
those measurements look weird. I would expect the resistance of a stepper winding to be 1-2 Ohm, maybe as much as 5 Ohm, but never above 10 Ohm.
You have disassembled the connector housing to identify the two wires to the switches and six wires to the stepper?
I would disregard the switch wires for the moment. That leaves you with six wires. The most common and probable circuit diagram is a center tapped two phase
stepper, per the attached pic. Note that it has six wires.
Its not impossible that it is wired as just a plain bipolar two phase stepper per attached pic, but note this diagram has only four wires. If I had a guess I would
say the two extra wires are a temperature sensor or switch....just a guess.
Identify the six wires and measure them again.
With either type I would expect zero conductivity (infinite resistance) between the two phases A and B.
Between A1 and A2 of each type I would expect less than 5 Ohms. Likewise I would expect less than 5 Ohms between B1 and B2 of either type.
Between Acom and either A1 or A2 then I would expect half of the total phase resistance, ie resistance between A1 and A2. Bcom to either B1 or B2
should follow the same as Acom.
Craig
Ok, i was able to open it up. At least parts of it.
Of the 9 Pins 4 go to the imit switches and 5 to the motor.
However on one pin there are two cables going to the motor. So I have 6 cables from 5 pins.
I just took another multimeter just to make sure. Unfortunately the Values are still true. (The White in the list below has no connection because it is going to the limit switches, So for the motor I have Black(2 cables inside housing), Purple, Blue, Green, Red)
Any ideas?
Hi,
well I would have to guess that you have a center-tapped stepper. The centretap, the two black wires, are commoned together.
For CNC purposes I think that motor is not up to it. The principle determinant of speed in a stepper is the inductive time constant of the windings. With such a high
resistance the inductive time constant will likewise be high, and therefore your motor will probably not turn more than a few revs per second, so your axis will be slow., possibly very slow.
Most steppers for CNC need to be able to get to 500rpm to 1000rpm, that is 8 to 17 revs per second, your motor I doubt will get to 3 revs per second.
Another issue is that the vast majority of drivers are bipolar, and because your two windings are commoned together by virtue of the commoned centertap they will not work.
You'll need a two phase uni-polar drive, and that may be hard to find.
Do you have a 24V or 36V power supply? If you did, you could probably make a very simple driver just to test it out. If it works then start looking to buy a good driver,
if it does not, or goes to slow, then at least you haven't wasted a whole bunch of money on a driver.
Craig
Hi,
Thanks for your answer, you really helped.
Speed is not an issue, small movement increments is in my application. To keep things simple I just bought a 5:1 geared Nema17 stepper motor, that should solve the issue.
Daniel