Objects Imported from Adobe Illustrator are slightly smaller in LightBurn

[esplinjl (J Lynn Esplin)]

I have created a bunch of objects and files in Adobe Illustrator. When I import them into LightBurn, they are all slightly smaller than they are supposed to be. To test this, I create a rectangle in Adobe Illustrator that is exactly 3" x 2", and import it into LightBurn. It is now 2.9861" x 1.9861" in LightBurn. I create a 3" x 2" rectangle in LightBurn, and then cut them both on the laser cutter and they are not the same size. They come out the size LightBurn says they are, not the size I created them in Adobe Illustrator.

Any ideas how I can fix this? Thanks.

[Rick (Technical Evangelist)]

@esplinjl

I create a 3" x 2" rectangle in LightBurn, and then cut them both on the laser cutter and they are not the same size. They come out the size LightBurn says they are, not the size I created them in Adobe Illustrator.

Thank you for this post, but I am a little confused by the wording here.

If you draw a square in LightBurn, say 3" x 3", then cut that, what does it measure?

It should measure 3" x 3". If it does not, there is an issue with the calibration of your laser.

[Hank (Hank Morgan)]

Is this a stroke width problem? Lightburn doesn’t recognize stroke width so if you’ve stroked an object in Illustrator and imported to LB it may appear a different size.

[Rick (Technical Evangelist)]

Yes, and this as well. @Hank is correct, so thank you for that. I do want to check that the laser is producing as expected due to the OP’s wording, though.

[TomWS]

Inkscape will do the same thing unless you’ve set it to use Geometric Bounding Box:
Edit->Preferences->Tools, Select Geometric bounding box
If it’s in Visual Bounding Box mode Inkscape will say the size is +1 line width (the Geometric Bounding box is considered to be in the middle of the line width).

[Hank (Hank Morgan)]

I know. I’ve been an Inkscape user for many years and it drove me absolutely crazy until I found that Geometric Bounding Box setting…

[esplinjl (J Lynn Esplin)]

When I make a 3" x 3" square in LightBurn, it prints the correct size.
When I import a 3" x 3" square form Adobe Illustrator in comes into LightBurn too small.

[esplinjl (J Lynn Esplin)]

Thanks for the input, I will check the stroke width in AI.

[esplinjl (J Lynn Esplin)]

When I make a 3" x 3" square in LightBurn, it prints the correct size.
When I import a 3" x 3" square form Adobe Illustrator in comes into LightBurn too small.

[Rick (Technical Evangelist)]

Thank you. I was concerned there may be something out of calibration with your hardware. The LightBurn result you are getting confirms your hardware is producing as desired and expected.

As suggested, Line width is the next issue to check. Source art should be designed with a very thin line weight, like .01mm.

[TomWS]

@Rick

Source art should be designed with a very thin line weight, like .01mm.

Line weight won’t matter (within reasonable bounds) if Geometric Bounding box is used (from Inkscape anyway).

[esplinjl (J Lynn Esplin)]

Line Width was the problem. I tested several line widths and the smaller the line width the closer the object gets to the correct size. Unfortunately, with my very old version of Adobe illustrator (CS2), I can’t figure out how to get the line width to go less than 0.25 pt. But at least I understand the problem and I can compensate if I need accuracy closer than the 0.0035 inch error I get with a line width of 0.25 pt.
Thanks for all the comments.