I’m trying to understand a strange behavior on my Ruida-controlled CO₂ laser rather than simply changing settings until it works.
At low engraving speeds, a test pattern containing both **Fill and Line** stays perfectly aligned. When I increase the engraving speed, the fill gradually shifts relative to the outline, but the final vector outline itself remains dimensionally correct.
For example, at 200 mm/s a 50 × 50 mm test looks correct. At 500–600 mm/s, the engraved fill begins to move progressively away from the vector outline as the scan continues. The amount of displacement seems to increase with the number of bidirectional scan lines rather than appearing as one sudden mechanical jump.
The interesting part is that:
* Calibration is accurate.
* Belts and pulleys appear tight.
* Repeating a vector cut gives the same result.
* Lowering acceleration reduces the effect but doesn’t completely eliminate it.
* The problem is much more obvious with highly fragmented artwork than with a simple rectangle.
Before I start changing random Ruida parameters, I’d like to understand **what is actually happening at the STEP/DIR and laser timing level**.
Could this be related to **PWM Rising Edge Valid / STEP pulse polarity**, scanning offset, acceleration, or some interaction between the Ruida controller and the stepper drivers?
What test pattern would you use to distinguish between a controller timing problem and an actual mechanical/stepper issue?
