[Greolt]

Ok I read posts all about RMS an peak. Square wave moving to sinusoidal at higher RPM.
All went over my head :withstupi

On the drives that came with a kit from China amp setting is done with a trimpot. Microsteping is set with dip switches

On Lou's sugestion I put my multimeter in series with one phase of a bipolar setup.

Then jog-stepped one microstep at a time till the amps peaked on that phase and adjusted the trimpot to the amps I wanted.

Is this the right way to do it?????

Next question

Repeated requests to China for info on the motors has been a waste of time.
No markings of any kind on the motors.

Looking on the Kellingnc website for motors that match the physical size and wire count I have come up with these assumptions.

Nema 34, eight wire, bipolar series, 3amps/phase

Nema 23, four wire, 3amps/phase

Does this sound like good assumptions or am I way off :drowning:

Any clever people out there that can help me out will be much apreciated :cheers:

[ger21]

There's no way to guess the current rating based on size and wire count. I've seen PacSci motors of the same size and torque available with 6 different current ratings.

[pminmo]

You should have information with the drive as to how to set motor current. Usually there is a reference voltage that you adjust and measure via a simple dc voltmeter. You method has issues.

[Greolt]

Thanks Gerry and Phil

I suspected that would be too simple.

I tracked down a PDF on the drive (thanks PatrickM) and this is all it had about setting amps.


"The driving current can be adjusted from 1.0A to 4.3A infinitely. The current will go down when clockwise rotate
the adjustable resistor; and the current will go up when counter-clockwise rotate the adjustable resistor."

Nothing else. What do you sugest? :idea:

[pminmo]

Post the pdf, and maybe we can help.

[Greolt]

Phil

The PDF is over the 2 meg limit.

I have read it through six times and the only mention of setting amps is exactly as I quoted.

It is very brief and written in Chinese-English. Looks more like a sales brochure than a tech document.

Thanks anyway, Greolt

[James Newton]

http://www.sxlist.com/techref/io/stepper/wires.asp may help figure out which wire is what. I would expect that some way of meauring the coils must be available that would allow one to compute the other ratings, but I don't know what it is.

[Greolt]

James thanks for that.

I figured out the wires and have the motor connected and it goes no problem.

What I was hoping to do was set the amps to the correct level on the driver.

Mostly concerned about the first question.

[pminmo]

There maybe be some clues even where it's not directly mentioned.

[Greolt]

Phill

This is the link that Patrickm kindly provided for me to the PDF.

Should have remembered this when I first tried to upload the PDF :withstupi

http://koeienuiers.nl/document_libra...otordriver.pdf

I am convinced that you won't find any thing helpfull but I would love to be shown up for a fool :stickpoke

Thanks for taking the time with this :cheers:

[pminmo]

Well, I can't see it either. I'd contact the mfg.

[Greolt]

Well that's my problem isn't it I've asked the manufacturer for this info on so
many occasions that it appears hopeless.

Thanks again for taking the time Phill. I appreciate it.

[pastera]

Looks like your going to need a good meter.

1 Rotate the current limit resistor fully clockwise (lowest current)

2 Measure (don't use the datasheet) the resistance of one coil of your stepper. For more accuracy, measure the shorted resistance of your probes and subtract from the coil reading.

3 Hook up the drive and measure the voltage across the measured coil while stepping, looking for the peak (step slow).

4 Set the current by voltage = stepper current * measured resistance.

You will need to turn the current reduction off to do this.


BTW: Did I mention that I hate products that have the chip IDs scrubbed! How are you supposed to repair the thing!

Aaron

[pminmo]

pastera,
Assuming the drive using pwm/chopping, unless he has some pretty sophisticated equipment, measuring AC current of a chopped waveform isn't very accurate, and in fact the readings could be very misleading. Plus across the motor coil that is being switched?

[pastera]

The DC setting on most digital meters has a low pass filter to allow for reading the DC value of the PWM signal. If the motor is stopped then the AC component is only from the PWM and is of high frequency.

I was assuming the drive was smart enough to use a slow decay (recirculate) current mode while idle. If the drive always uses fast decay, the voltage will be wrong.

So, measure the current directly, just be careful not to allow the leads to loose contact as this could create some nasty spikes.

The best way would still be to measure the votlage across a sense resistor but not many people have a cabinet full of non-inductive low value power resistors.

Aaron

[pminmo]

Hmmm,
Fluke has been around measurements for a long time. Take a look at:
http://us.fluke.com/usen/products/fe...(FlukeProducts)

Notice the difference in the two models, the 83V and the 87V. The goto the bottom of the page.

[Greolt]

I really do appreciate your input Aaron and Phil.

Heading off on two weeks vacation tonight. Don't know if I'll be able to check the forum in that time.

So if I don't reply I'm not being rude