Can't figure out how to engrave without tray

I read several topics about what to do when working without the tray.
I made the helper from Guide for engraving thick objects without crumb tray
Added materials under my box lid until it hits the helper.
I set the focal point at 0.01 and also tried with 0.02.
This is the result:
As you can see it started engraving at the wrong location. It even engraved outside the box lid into my craft material.
What are the correct settings to do this?

Did you set the material height underneath unknown materials at that number or in the settings under focus height?

I set it in the unknown materials and the same number is in the focus height.
Shouldn’t they be the same?

You did it right then. The number you put in for unknown materials is both used for getting the camera as accurate as possible and setting the focus height unless you choose to manually change that in the settings. Personally, i’ve found the Cutting Without the Crumb Tray - The NO MATH Edition to work out great as long as you have set of calipers. All of the crumb trays seem to have slightly different heights and the creator of the guide you used made it specific to his glowforge and crumb tray.

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It’s hard to tell how far off the engrave is because there is no scale.

How thick is your material? And how much material do you have stacked underneath it?

Jig, jig, jig.

You can even jig a no-crumb engrave, I have a process that I use but need to document it.

Nutshell: make art file with jig cutlines in correct placement. Raise cardboard to crumb height. Disable engrave, cut jig out of cardboard. Place item in jig also at proper height. Set proper engrave height, turn off jig cut line. Engrave.

I should really document this.


I struggle with going trayless too. :-/ I agree that your material height number could be the issue. I just want to make sure, have you measured the height of the helper guide you cut out? I was thinking it’s possible the scale was changed when you brought in into the GUI.

Thanks all for your help and suggestion.
I now know I shouldn’t take short-cuts.
I followed this tutorial Tutorial: How to cut without the Crumb Tray (Honeycomb) because I don’t have a digital caliper. After doing the math my tray is 35.5 mm tall. After adding extra material my total height is 36.4mm. So I set 0.9mm is 0.035" as my material thickness. And now my engraving is at the position I need it to be.

I’m not sure about the focal height. Does this influence the engraving dept?
I need to engrave about 1mm to add some inlay. I now increase the power making a lot of burn marks.

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Focal height will override the autofocus mechanism. To get 1mm of depth, you’ll just have to experiment to see what gets you there. If you’re making just one, just start easy and do multiple passes. Don’t move the material and run another pass until you’re satisfied.

If you’re planning to engrave an inlay, you might consider a cleanup score around the edges once the engrave is complete. It helps get the gunk out and generally makes a more consistent pocket.


One other note on engraving for inlays, your LPI setting will affect your engrave depth, as well.
I was setting up an inlay, had the exact setting I wanted, then I increased the LPI to get more detail. It became deeper, so my inlay was no longer flush with the surface.