Jagged cut line only after a radius into a diagonal line. w/image

Ruida 6445G on a DIY 65x36" Laser and Lightburn 1.1.01
Gantry travel is side to side.
\I have an issue where anytime I have a radiused corner that leads into a diagonal line I cut a jagged cut.
I can slow the cut down to 30 mm/s and it cleans up but this is material I normally cut at 60-70mm/s and the pattern has many corners. This is killing my cut time.
The jagged cut is often worse when cutting vertical but still happens horizontally. It will got around a radius into a vertical or horizontal line without issue.

I have checked and tightened all bearings and rollers and roller wheel adjustments on the side rail carts along with increase and decreased belt tensions.
I have upgraded my gantry cart to a linear rail. I thought maybe this would stiffen things up. I also went to a wider drive belt.
I have run cuts while applying some pressure to the laser head. I thought maybe preloading it some would help take any flex that it might be experiencing?

Attached is a photo of the issue I am having. If I run a zip zag pattern with pointed peaks and valleys, I have no issue and can run it at full speed.
If there is a radius, .03125, .0625, .125” etc added to the peak or valley then I get a rippled line well past what you would thing a hard direction change would induce.
In the bottom pattern I alternated between pointed and radius direction changes and it only happens after the radius.
It cuts great circles as small as 1/16" at normal speeds.

Hardware all seems fine. The laser head will flex slightly if I push on it at the focal lense but this does take a decent amount of pressure.
Curious if I am asking it to do something it can’t, if this head flex is causing a resonance or if there is something in my controller or Lightburn that I would need to adjust to slow down the cut just around the radius? What gets me is that this is almost a ripple effect that continues well past the direction change.

I think you hit it…

Looks much like a resonance trace… you are also adding energy in multiple directions.

What is the physical size of this aberration…?

At certain speed(s) some part(s) of the machine may resonate…

The problem with a diagnosis is that you can’t really determine the speed this is occurring.


Make sure you have a backup of the Ruida controllers setting before modifying anything

Since you confirm that everything mechanical you know is tight and/or checked.

I would try modifying the ‘acceleration’ and/or ‘start speed’ and see if that would help dampen the effect. You should see a change in the ‘pattern’ so to speak…

There is also an ‘idle’ speed, but I think that is just how fast it can move without lasing.


The Ruida 6442G manual states


Turning Speed: the turning speed at closed-angle corner, the lowest speed in the whole cutting process.

Turning Acceleration: the acceleration speed at the closed-angle corner when cutting. If the two speeds are set too large, vibration will be happened when turning; if set too low, it will influence the cutting speed.


Never dealt with or seen where they can be modified. It may be via the controller, sounds relatively suspicious that this may have something to do with the issue.

Good luck

:smile_cat:

Thanks for the reply.

My manual shows tuning and acceleration speed under user parameters on the control panel. My panel does not show these parameters at least not listed by that name. I will to look around and see what I can find on these setting. not sure exactly what they are in relation to. I changed them by factors of 100 and 1000 and saw no visible changes in cutting or increase in quality of cut

The pattern shown about ranges from .75" to almost 3" at its tallest. The “ripple” looks to last almost the full length of the line segment its on even the tallest cut looks terrible on the climb up then crisp after the sharp peak.

I feel like this has to be something lose but like I mentioned earlier, even if i press against the air nozzle to preload it a bit I still get the same poor cut line.

I dont know why it will cut a circle (big or small) crisp and at high speeds but can handle this corner radius.

I would think that’s too large for a resonance issue.

I’ll have to think about this…

:smile_cat:

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