Hello. I’m using an OMTech 55W laser, Ruida controller trying to do fill patterns.
I’ve read the threads with similar issues (loose belts, too high acceleration, shifting workpieces, etc) but I don’t believe I have any of those issues despite the results. However open to opinions and experience here.
My fill speed is 150mm/sec, x acceleration is 5,000 (mm/s^2), y acceleration is 2,000, x start speed is 20 mm/sec, y start speed is 15
When doing a fill on letters the output seems to skew and/or shift
Note the skews are different on each piece (one I cancelled), with the seven in particular slanted much more than the design, while other letters have shifts to the left. I’m doing a bi-directional fill. The top image was a fill of the whole project at once, the bottom image a fill of each individual shape/letter.
I ran two tests, one of a low-density fill of a large box and the patterns did not shift (both at 400mm/sec).
The second test was of individual fill boxes at 400mm/sec, again without fault. The moiré patterns (if you’re seeing them) are not on the actual test output but must be a photo artifact.
Is it possible that my acceleration values are too high for my machine, even though they seem to be in the normal range? It clearly looks like the bad examples are missing steps, but there does not appear
I have a very similar machine, OMTech 50W. The values are lower than I believe mine were, so I doubt that’s the problem.
From what I can see it looks like it’s loosing steps but I can’t tell if it ever recovers from that.
I’d suggest first eliminating any mechanical issues… ensure belts, pulleys and especially grub screws are firm and holding. The electronics are pretty dependable, so check for the likely cause…
I’ve messed with this a lot and usually you can hear it loose steps…
Here is my machine almost original and in almost current configuration.
There is an obscure setting that needs to be unlocked in the Vendor Settings under machine settings:
If your output looks like this, you likely have your motor pulse step polarity set incorrectly. On Ruida controllers, there’s a setting called ‘PWM Rising Edge Valid’ that you can change for each axis that tells the controller whether the rising edge or falling edge of a step pulse is what the motor driver is looking for. Toggling this may fix skewed engraving.
The fix is relatively simple. In Edit > Machine Settings, look in the X & Y axis motor settings section at the bottom, and look for the value of ‘PWM Rising Edge Valid’ on the X axis. Change that - if’s it’s checked, un-check it, or vice versa. Then, copy the new setting over to the Y axis as well.
Unlocking vendor settings comes with a warning so I wasn’t clicking around in them. But switching this setting to “off” gave me a successful job.
Thanks for the attention to this – at this point I think this can be flagged “resolved”
