I’m looking for advice with an ongoing motion problem on my CO₂ laser, and ideally recommendations for an experienced laser engineer in or near West Sussex, UK if I cannot solve the issue !.
The machine is an upgraded HPC LaserScript 1290 fitted with:
Ruida RDC6555G controller
80W RECI CO₂ laser tube
The main symptoms are:
Circles do not join cleanly at the start and finish point
Straight cuts have a repeating wavy or jagged appearance
Some corners have small tails or distortions
The problem appears more noticeable at higher cutting or travel speeds
So far, I have:
Cleaned and inspected the X- and Y-axis belts
Adjusted and compared belt tension
Checked the timing pulleys and drive belts
Inspected the rollers, guide bearings and linear motion
Checked the gantry alignment
Checked the motor couplings and drive shaft
Tested the stepper drivers
Reduced speed and acceleration settings
Confirmed that the artwork itself is correct
I initially found that the Y-axis drive belt was excessively tight. Loosening it removed the abnormal noise, but the poor cuts and distorted circles remain.
At this point, I’m unsure whether the fault is a damaged belt, pulley, bearing, stepper motor, drive shaft issue, electrical problem or something else I have overlooked.
I have customer orders outstanding, so any diagnostic advice would be greatly appreciated. I can also provide close-up photographs, videos of the machine moving and test-cut files.
The workshop sits normally around 20 - 30 degrees depending on what machines I have running, however this morning its currently 20 and the problem is still there.
I have tried taking the side door off and using a large 18" fan to blow across the steppers, psu’s etc as I was concerned a little about this during the last heatwave !
I’d think, somewhere, you have a loose Y axes. At least something is loose. I base that on your photos. These are sometimes misleading. As it looks good along the Y axes, meaning the X axes is working. It fails along the Y axes.
Both of these show the same symptoms. If you notice where the Y axes should not move, it is.
Also what makes me think it’s something loose, this is next to impossible to make a mistake that can cause this. Sometimes before I get too far, I think can I get the software to do this. I doubt you can without a lot of work, so I’d go with hardware.
Since it’s clearly something loose on the Y axes, I’d start there.
Keeping belts tight, but not too tight is something that is learned from experience. I can’t tell you how to do it, maybe make suggestions.
This can be anything from the head/lens assembly being loose somewhere or about anything else in the gantry system.
Thank you for your input — you were absolutely right that something was loose.
I completely stripped and rebuilt the Y-axis, checking everything from the stepper motor onwards. Although the axis was running smoothly afterwards, it still did not resolve the problem.
I then turned my attention to the X-axis and laser head assembly. I found that one of the laser mirrors had become loose in its holder. It appeared secure at first, but when I physically pressed it, I could feel the movement.
Once the mirror was tightened properly, the problem was completely resolved.
A very simple fault in the end, but one that took me around 36 hours, a partial machine rebuild and a considerable amount of swearing to find!
Thanks again for pointing me in the right direction.
