Cuts in the wrong location / offset

[ApexCrafter (Toni Vaskenvalaja)]

I’m running Lightburn 1.4.00. I should renew my subscription, but money’s been tight.

All of the sudden, the cuts are being made in an offset, looks like both X (positive) and Y (negative) axis. The prototype was cut fine. After that, I made some alterations to the design and the offset appeared. The preview shows that everything should line up correctly, but the laser does something different. I’m 99.9% sure it’s not belt slippage or some other mechanical issue, since I’ve cut other designs in the mean time without issues (that have both engraving and cutting in the designs).

This might be a Ruida issue, not sure. When the file is being uploaded to the controller, the size is over 600 MB. Could the file size be an issue? Maybe I need to update the firmware, I haven’t done that since I got my machine a few years back. I’ll look up how to do that next.

UPDATE: Updating to the latest Ruida firmware and the latest Lightburn version did not fix the problem, unfortunately.

[ednisley]

@ApexCrafter

This might be a Ruida issue

It’s likely you have a layout that triggers the Ruida “skewed engraving” gotcha, which boils down to the wrong polarity for the STEP signal.

A previous discussion on a similar problem and its resolution:

Image shifting and bunching up but cut out is OK

Red-Black 90w Laser Ruida controller engrave 400mm/s 25% Fill 450mm/s 20% Cut 25mm/s 65% Birch ply held down pins belts are tight so are stepper motors When doing a engrave/fill and cut I get the fill shift while the engrave bunches up, cut out in just fine. This is repeatable, and all come out the same, like it was meant to be, how do I attach image?

[ApexCrafter (Toni Vaskenvalaja)]

Thank you, thank you, thank you! Problem solved. PWM Rising Edge Valid was true for X and Y axis and I changed them both to false. Now to research what that setting actually does to actually understand the problem.

[ednisley]

@ApexCrafter

what that setting actually does

The effect is pretty well described in the doc link, but it boils down to misplacing a STEP pulse when the DIR signal changes.

AFAICT, CO₂ lasers with separate stepper drivers bricks always have a FALSE setting for the polarity, because the brick should trigger on the leading edge of the STEP pulse (when it goes active) rather than the trailing edge (when it goes inactive).

Tracing the logic through all its inversions can only be done on a low-caffeine day …