Losing position at end of job

[anakaine (Random Person)]

I’ve just spent a long time upgrading an old machine to a Ruida controller + lightburn. Almost everything now seems to be working, happy days.

One thing that is occurring which I cannot seem to resolve is that during complex jobs there often seems to come a point where the controller seems to lose position. A good example of this is a recent cut I did where in one layer in light burn I have a circle with leaves and vines and chains, etc some complex geometry. All gets cut quite well. In the next layer I have the outline of two birds - very simple curves. The laser has tracked the initial cut file very well, but when it gets to the birds, it completely loses its mind. The birds are cut over the top of the existing cut path of the complex geometry, and their outlines are wobbly, not connected at the end, and just generally a piece of spaghetti. Occasionally it will even forget to cut a line.

I’ve had the above scenario happen on a number of occasions with different files.

So things I’ve tried:

• Slowing down the machine maximum speed, ramping, and travel settings. I’m down to a max speed of 250mm/s at the moment, and ramping a little slower than that.
• Doing material tests and getting my overrun offsets etc correct with a micrometer. All the squares tend to come out well enough.
• Transferring the cut files to the ruins controller and hitting go. Still get screw ups late in the job.
• Running the cut files from the PC via light burn. Still get screw ups late in the job.

Months ago I posted about issues with bearing, motors, etc, and was given some good advice. Given this was an old Chinese laser that had quite poor maintenance I replaced all the bearings, one of the motors, the gantry carriage and runners, end stops, and whilst putting in the new computer etc replaced wiring etc. I’m absolutely confident in the mechanical and electrical quality of the upgrades at this point, though am not well versed in things like stepper motor controllers to know if I should be chasing a software setting, communications setting, or controller issue.

[jkwilborn (Jack Wilborn)]

Have you run this through preview? … I assume it appears OK… but?

If you don’t mind posting your artwork (.lbrn) file and a photo of the results… We can still look at it for any anomalies. We understand if you wish not to.

It sounds like you are right in that it’s unlikely your Lightburn file from the symptoms.

I’m trying to think of what could cause this and the only thing I can think of is speed/acceleration values… you artwork may show where this could occur.

Have you looked at the motor drivers to see if one of them faulted? They have a green power led and a red fault led for indicators.

Can you tell if it’s one axes over another… does it shift in any single direction?

The Ruida, in most instances loads the whole file. Not sure exactly how it runs if you send it, at some point it tells the Ruida to execute the code… don’t know if the whole thing is loaded or not.

Photos would be good.

[anakaine (Random Person)]

Still hoping for a little help on this if anyone here has some ideas or has seen it before.

[ednisley]

@anakaine

some ideas

This looks a lot like a communication problem destroying chunks of the job between the PC and the controller.

First of all, clear all the stored files from the Ruida controller’s flash memory, which you can do from LightBurn or the machine’s console. Ruida controller behave strangely when their memory fills up, so scrubbing it clean is always a good idea.

To diagnose the problem:

• Use LightBurn’s Send button to send the job to the Ruida controller and store it as a named file in the controller’s flash memory.
• Run that file from the laser’s front panel

If the stored file fails the same way each time you run it, then the data was damaged along the way, the file contains damaged data, and the controller is correctly performing the damaged commands every time.

If the job fails differently each time, then the problem is between the controller and the laser head, because the controller is running the same commands and producing different results.

To fix:

If the PC connects to the laser with a USB cable, switching to Ethernet will dramatically improve the results. USB was never intended for industrial applications and fails when confronted with typical machine noise.

If you’re already using Ethernet, there may be an overlap between the controller’s fixed IP address and the router’s DHCP assignments. The router can assign the laser’s IP address to another device, so that network traffic intended for the laser collide with traffic for the other device. These collisions occur randomly and are uncontrollable.

You must either:

• Pick the controller’s IP address so it does not fall in the router’s DHCP range or
• Adjust the DHCP range to exclude the controller’s address

How you tweak the router depends on the router; we’ve seen some cable-company routers refusing to be tweaked. Knowing the DHCP address range will go a long way toward isolating the problem.

Obviously, if you’re switching from USB to Ethernet, you must assign the controller’s IP address outside the DHCP range.

But, as the bluesman said: if it wasn’t for bad ideas, I wouldn’t have any ideas at all …

[jkwilborn (Jack Wilborn)]

@ednisley

you must assign the controller’s IP address outside the DHCP range

My last Linksys I purchased, doesn’t seem to look at anything outside of the DHCP set range.

I found I had to put it within the dhcp range and use the devices mac address to bind an IP to that mac address…

Just a heads up

[anakaine (Random Person)]

Just a quick post to hold this topic open. I believe i have found a solution: its related to microstepping resolution and memory issues on the controller.

Ill come back to post with photos and an update.

[SnakyWarrior (Pantelis)]

I have the same problem its definitely LightBurn problem.
i used to work with RDworks i had no issue.
It seems that the problem can be solve by turning all the settings off from optimization options.