Rotary seamless etch wrap around

LightBurn Software Questions
1

Guys,

I am trying to achieve a seamless pattern engrave 360° around a cylinder. I dumped my roller style rotary for a chuck style with a 5:1 gearing. I have verified my steps per degree in grbl as I can etch a horizontal line, rotate 360, 720, 1440, or whatever and still hit that same mark exactly again and again.

So in the rotary setup I specify an object diameter and it provides a circumference. I create a graphic with that same exact vertical dimension but no matter what it seems that the pattern comes short and I have a gap. Am I missing something?

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2

A quick update, I just tried

Cutting a 219.911mm vertical line and it meets one end to the other.

Also tried rastering the same dithered rectangle in Laserweb and it also lines up fine.

Seems to be an issue with Lightburn rastering.

Please help

3

Was this image dithered outside of, and prior to importing into LightBurn? If so, have you rotated this image from its original orientation? Are you using ‘Pass-Through’ on the ‘Cut Settings Editor’ window for this image? Please show a screen capture of the ‘Cut Settings Editor’ window for this layer. Double-clicking the layer exposes this window.

4

Hi Rick,

The image is a solid gray rectangle. I scale it to the desired size in Lightburn and apply Jarvis dither. below are my settings. Should I enable pass through? Or disable overscan?

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5

I exported the G-code and tallied up the A moves. It ended up totaling 359.04 degrees

6

Seems like a bug. I tried this a few different ways now varying the line interval. I tried using values which divide my vertical height by 360, 720, 180, 1440. Going through the G-code it stopped short between 1 - 2 degrees for the first 3 and overshot by 1 degree for the last.

I do have some urgency to complete this job, so I am hoping there is possibly a quick resolution to this issue.

7

The developer is currently moving across the country.

8

It is also possible that the object diameter you have input into LightBurn is not exactly correct.

In either case, can you adjust the object diameter in order to make the ends meet exactly?

9

Yeah, that is why we moved from using a roller style rotary to a chuck. Our cylinders outer diameter would vary slightly from piece to piece and would cause inconsistencies in the final etch pattern. Using a chuck style rotary should eliminate the error from slightly different diameter tubes because the distance traveled is not dependant on the actual tube. Instead the software should just create evenly divided lines totalling to 360° if the calculated circumference and object height match.

We can compensate manually, but it’s a quite time consuming to test and expensive to verify as these are quartz crystal tubes of which we have many diameters.

10

Hi Guys,

If this is indeed a bug in the software, how realistic would it be to have some sort of fix available this week?

11

As I mentioned in an earlier comment, the developer is in the middle of a cross country move, so it patience will be required.

12

Understood, but what does that mean? 1 week, 1 month? I just need to plan accordingly.

13

The glass in the picture appears tapered. Is that true or just a distortion from the camera/lens? If it is tapered, how did you compensate for the taper?

14

Not tapered. But that should not matter on a chick style rotary for this specific issue.

15

Hello Lightburn Support, have you had a chance to look at this a bit further?

16

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