Cohesion 3D rotary use causes Ruida controller to shut off and restart

Hello,

I have recently purchased the Cohesion rotary attachment, and set it up for use with LightBurn (currently 0.9.07) and a Chinese red/black machine with a Ruida RDC6442S-B(EC) controller. I used the LightBurn setup procedure on github.

When I attach the rotary to the Y-axis, and switch on “enable rotary” in LightBurn, everything works for a couple of test pieces. After around 15 minutes of use the controller starts shutting down mid-job. When this happens, sometimes the panel blinks white and nothing more happens. Sometimes the controller turns back on but can’t restart the job properly due to the y-axis not being able to home.

The stepper motor feels excessively hot to the touch. I haven’t measured the exact temp yet but I would be burned if I tried to touch it for more than a quick tap with the back of my fingers. Real hot.

When I remove the rotary, and set things back to normal in LightBurn and on the machine, I can engrave normally again.

Are there any known issues with Ruida controllers? I’m not finding anything on this forum from a search or in this section. Some other issue I haven’t considered?

Thanks for your time. I like the design of the rotary, and am looking forward to getting some hours in using it.

Quinn

Another detail I forgot to mention.

The y-axis moves(intervals) are noticeably slower than flat table engraving while the job is taking place. Moving the y-axis manually with the rotary connected seems to happen at normal speeds.

Hi Quinn. Nice to have you with us.

I have a few concerns:

This is a large concern. This is why this the following note exists on the getting started page:

Cohesion3D Rotary:

Rotary instructions start here: Cohesion3D Rotary Unboxing & Setup

IMPORTANT NOTE: IF YOU HAVE A LARGER MACHINE WITH DSP/ EXTERNAL STEPPER DRIVERS, DO NOT PLUG THE ROTARY DIRECTLY INTO THE EXTERNAL DRIVER WITHOUT FIRST CHECKING AND ADJUSTING THE DRIVER CURRENT SETTINGS. YOU CAN FRY THE STEPPER MOTOR ON THE ROTARY. CONTACT US ON THE FORUM SO WE CAN WALK YOU THROUGH THIS PROCESS: https://forum.cohesion3d.com/c/cohesion3d-rotary-attachment


The stepper driver should be set to approx 1 amp and the rotary stepper motor should be cool to the touch.

I would recommend starting there, and let me know if the issue persists.

To confirm, you are hooking up the rotary motor to the existing Y stepper driver?

Some other thoughts:

Plenty of people use rotary units with Ruida as we can see from the LightBurn forum.

If you told me this with no other context, I would say that your laser power supply is the problem.

I have a blue/white 50w with Ruida. The power supply inside was a dual voltage 24v/5v and the 24v rail had what I calculated to be barely enough amperage to run the 2 stepper drivers hooked up to it.

However, see if turning down the current on the Y driver for the rot fixes the issue as I said above.

I appreciate it - I can’t put into words the amount of care we put into making it.

1 Like

Thank you so much. I don’t see that note on the unboxing & setup post. It goes through the steps of assembly, which I didn’t need to do since it happily came assembled, and then talks about electrical docs being in the works. After looking further just now, I did find the “getting started” page. I missed it before.

I did look up the specs for the stepper motor but maybe I misread things. ldomotors website says that LDO-42STH38-1684 is 1.68 amps per phase. My driver is set to 3.0 amps rms but I thought it meant total. It sounds like maybe it’s also per phase.

In any case I’ll rectify my mistake. I have a feeling it’ll work as expected once I do. After that I’ll post back here to clarify. I am definitely always learning. Thanks again.

The packing slip in each box links to the start page. I’ve been thinking about more blatant ways of presenting it to users, and also the above warning in the case of the rotary, such as a sticker that blocks the zipper to the bag with the motor cable, or one that blocks the motor connector port. :slight_smile:

Yeah, that’s not how it works. Stepper motors can run very warm but piping hot is not a good thing. At 1.5 amps the motor will be warm, at 1.0 amps it should be cool to the touch and that should be enough current for most applications.

The last guy plugged the motor into a driver set a 3.33 amps and flash fried his rotary motor. That’s why those warnings showed up. So let’s hope that didn’t happen here.

Even the most disciplined engineer is not going to have a 100% rate of remembering to change the motor current dip switches on the Y stepper driver every single time they switch between rotary and normal Y.

I would recommend installing a separate stepper driver specifically for the rotary.

That’s what I had in mind with the separate driver offering here. Double it up with the Y driver for power, hook up the rotary motor to the outputs whether that’s directly or through an aviation plug, and you would switch the 3 pin terminal block with the step and direction signals on the Ruida controller side when you want to switch between normal Y and Rotary.
You would have to wire up the 5v to the + contacts on the driver, and the step and dir - are the signals going to the ruida.

1 Like

Thanks Ray. I definitely rushed when setting this up. Being busy is a double edged sword, and I should have paid more attention. I don’t think I fried the motor but even if I did, that’s on me. Thankfully these motors and drivers are fairly inexpensive.

This product looks and feels solid. That’s the big value for me and what I need it to do. Thanks again.