Rotary burn bottom edge is compressed

[twmaster (Mongo)]

I’m burning some tumblers on my rotary. When I attempt to etch the image the bottom is being compressed.

See the photo. The right side of the Harley image on the black tumbler is narrower (would print as the bottom in the rotary). On the orange tumbler (I just etched that same edge then stopped) the image etches fine so long as I draw a box around the image and set the box to a tool layer.

I heard a presenter in a YouTube video mention this using a box. That did fix this for me. But I cannot find the video I remember seeing this in.

While I’m mostly OK with drawing the box, I’d like to understand why this is happening and if there’s a way to correct without the additional tooling layer box.

Lightburn 1.4
Wheel type rotary attachment
100W Co2 machine

As always, if I’m dense and missed something please hand me a Coke and point me in the right direct.

Thank you.

[twmaster (Mongo)]

No ideas??

[JohnJohn (John Johnson)]

I’m puzzled by this.

Anything in the Tool Layer, shouldn’t produce (and to my understanding) shouldn’t change the output behavior.

If you’re willing to share a couple of files, I think I can troubleshoot it.

Take the Harley Davidson project,

Set up the project for the rotary without the box in the tool layer.

In LightBurn, click File, click Save GCode, and save that file somewhere convenient.

Draw the box and put it in the tool layer to fix the problem.

Then click File, click Save GCode, and save that somewhere convenient with a different name.

I’ll examine the two files. Hopefully I can see what’s causing this ‘fix’.

[twmaster (Mongo)]

I’m on a DSP machine. Do not see a way to export as Gcode.

I was doing some tests on blue tape while setting up for a 20 piece job. I noticed the edge of the tape was burned through and again was obvious the edge was compressed just like the HD image.

I’m happy to post whatever files you ask for. Thank you.

[JohnJohn (John Johnson)]

May I ask which controller you have in your 100W Monport CO2 engraver?

I have their K40 replacement controller here, but not the DSP.

[twmaster (Mongo)]

Hi John, our 100W machine has the Ruida 644 or similar controller.

I think I’ve figured out what is happening. It’s not a Lightburn problem. It appears to be mechanical with some backlash to the driving wheels via belt/pulleys. I’ve checked all are tight but still see the backlash.

While I have not figured out where the mechanical issue is I’ve been able to engrave an image without the compression of the bottom edge by advancing the rotary just 1mm prior to starting the engrave. This explains why with a tool layer box the ‘slop’ is removed.

After some additional searching here it seems there are a few others with the same issue with the same brand rotary tool. Mansfield Customs.

Will report back when I find more info.

Thank you for your offer to help.