What dip switches to set on Stepper Driver board?

[johnnyt74]

Hi all,

I'm brand new to all this CNC stuff and so far loving it!

I've got NEMA 34 stepper motors, The name plate says 5.6A.
http://www.cnczone.com/forums/attach...d=347294&stc=1

I'm using the following type of driver...
http://www.cnczone.com/forums/attach...d=347296&stc=1

These have got dip switches on. Currently I just have all the dip switches ON (which equates to 400 pulse/rev and 2.8A Peak current).


http://www.cnczone.com/forums/attach...d=347304&stc=1

I'm not sure what these switches are meant to be set at? Am I meant to have the power ones set to 5.7A Peak or set to 5.6A RMS ??

Also, what difference does the pulses/rev make? Is the more pulses per rev linked to the accuracy of the motor? In which case do I just want it set to the maximum?? Or is it software dependant?

I'm using LinuxCNC to send the g-code to my motors.

(Currently I don't have the motors on a machine - they are just sat on the floor and I've just been testing the connectivity etc).

Also worth noting that I'm just in a domestic property and not an industrial environment so don't really want to be pulling lots of Amps down my mains (plug fused at 13A anyway).

Any help would be greatly appreciated.

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[ger21]

You're showing two different drives, with different settings?


I'd set it to 4.9A peak, and either 1600 or 2000 Pulse/Rev.
You need to set up Linux CNC to send the correct number of steps to match your setting on the drive.
Higher steps/rev makes the motors run smoother, but it's generally considered that you don't need more than 8x-10x microstepping (1600 or 2000 steps/rev)

[johnnyt74]

You're showing two different drives, with different settings?

Yep, the first picture was just a 'stock' picture that I got from Google to just show the type of driver. The second pic is my actual driver.
I didn't notice the difference! Well spotted Gerry!! You have eyes like a hawk sir! :-)

I'd set it to 4.9A peak, and either 1600 or 2000 Pulse/Rev.
You need to set up Linux CNC to send the correct number of steps to match your setting on the drive.
Higher steps/rev makes the motors run smoother, but it's generally considered that you don't need more than 8x-10x microstepping (1600 or 2000 steps/rev)

Thanks for this info Gerry (as always). I just wondered why you settled on 4.9A peak? Is there some sort of formula to do with steps/rev or something else that leads to 4.9A?

Thanks again :-)

[ger21]

You can probably use the 5.7A setting, but I usually use a little less than the rated current, and that's the next lower setting.

[johnnyt74]

Thanks Gerry. I've change all the dip switches and changed the settings in LinuxCNC but this has created a couple more questions if you don't mind...

The stepper driver has the following info provided in the manual (which is in German unfortunately for me)...



I took this to mean that in LinuxCNC the following settings were needed...
Step Time: 4500ns (the 2500ns at the bottom of the pulse step added to the falling edge and rising edge of 1000ns each?)
Step Space: 4500ns (same as above?)
Direction Hold: 1500ns (the 2500ns between PU and DR minus the 1000ns falling edge?)
Direction Setup: 5500ns (the 3500ns between the DR and MF signals added to the falling/rising edge of 1000ns each?)

Am I right with this or am I working this out wrong?

Also, in LinuxCNC for each axis they ask for the "Maximum Velocity" and "Maximum Acceleration". I've no idea what to put in here. So far I've just put in 25mm/s (1in/s) for velocity and 750mm/s (29.5in/s) for max acceleration.

Any guidance on this would be most welcome. Thanks

[Toinvd]

Your stepper driver DQ542MA will most probably work without problems on the default values from LinuxCNC
Your motor has 6.5mH inductance.
with 36 volt supply to the driver that gives a maximum speed about 275 rpm if your spindle is 5mm per rev it comes to 1375mm/min so about 23 mm / sec ( your 25 is a good value )
at 48 volt supply the values are 370 rpm 1850 mm/min 30 mm / min
the value for acceleration depends also on the mass that needs to be set into move. just try out some values on your machine and when loosing steps, set a value realy below ( -25 % or so )

[johnnyt74]

Ok thanks for the help. I'll wait until the rest of the machine is built and then do a bit of experimentation. Thanks again :--)

[Jono888]

Hi J, Did you find any info on what/how ip switches should be configured. Sort of got the part about AMPS but what about Resolution and Smoothness? Best, Jono

[johnnyt74]

Hi J, Did you find any info on what/how ip switches should be configured. Sort of got the part about AMPS but what about Resolution and Smoothness? Best, Jono

Hi Jono

I've currently got it set to 4.9A peak and 25,000 steps per rev. ** Disclaimer ** - I've not currently got the motors connected to the machine (because I've not built the machine yet - I'm still finishing off the control panel. So I may need to change these settings when I actually start trying to router something out.

If you get any more info on this then please post back in this thread as I think there is a lot of this that's going to be a bit of trial and error. :-)