Replaced stepper drivers, now raster engraving is messed up.

So I bought this laser back at the begining of the year. 600x900mm work volume 90w RECI tube Ruida RDC6442S-B control.

It had no name stepper drivers running at 24v that could not reliably move the laser head back and forth, way to many lost steps.

After fighting with the builder for 6 months gave up and installed 2 Stepperonline DM542T digital drivers with a 48v PSU.

That seems to have solved the lost steps issue, I have been unable to cause any steps to be lost under normal operation upto 500mm/sec scanning. (500mm/sec raster engraving always caused lost steps.)

But I have a new issue, I am certain it is just a setting somewhere in the Ruida controller as the problem did not happen before replacing the stepper drivers.

When raster engraving the laser seems to activate early in each direction while scanning. The below picture has various speeds with outine fill engraving.

For scale the vertical section of each engraving is .400 inches.

I am pretty sure I could adjust this in Lightburn, but would rather make a permanent fix in the Ruida Controller.

Help!

https://www.pdxmc.com/uploads/CO2Las...terengrave.jpg

Also tested in RDworks and Lightburn same issue happens in both programs.

Quote:

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Originally Posted by nlancaster

Also tested in RDworks and Lightburn same issue happens in both programs.

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Hi,
i think this is same problem like this:

https://www.cnczone.com/forums/gener...eps-think.html

and the solution is here:

https://forum.lightburnsoftware.com/...ngraving/11911

Quote:

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Originally Posted by nlancaster

Also tested in RDworks and Lightburn same issue happens in both programs.

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did you ever solve this? I did the same thing, and now have the same result as you with timing being off. no setting seems to help. I have tried changing the phases A swapped with B. I have tried reversing one of the windings on A and also on B to make the steppers drive the other direction (then have to change the corresponding direction setting on the ruida machine settings). I have also tried the rising edge vs. falling edge valid setting, which this also makes the motors run in the opposite direction, but no matter what configuration, I have the same issue that you show here.

I will add that I have reverted to the DM545A stepper drivers that were on my machine from the factory. Without changing anything but this, the engraving is spot on. I kept my new 48V supply, and set it to 45V. The DM545A drivers emit a very annoying audible screech at idle.

My assumption right now is that the DM542T is a superior driver especially since it doesn't whine, but in timing critical applications like laser engraving, it might be adding some of its own delay in acceleration for example. This is something that you would not notice say on a CNC router, but on a laser engraver there is no room for timing offset or acceleration that is not true to the called for acceleration. That's my take at the moment.

I'd be interested in using the 542T drivers, or an even better driver if available. I had thought to go to hybrid steppers, but am worried that they would add corrective movements and screw up the timing.