Community Help Needed - Tray Removed Focus Issues

[glen]

Hi Folks,

before I go to support with this issue I would like to ask everyone here if this is a problem or not.

I have not used the GF with the tray removed recently so I want to check if I’m doing something wrong. I want to engrave something on the lid of a wooden box. The box is just over an inch think (26.8mm) so I need to do this with the tray removed. However, when I put the lid in the GF and go to do the engrave, the lid appears much smaller than it should.

The square should be the same size as the lid. When I repeat this engrave on some scrap plywood with the tray in everything appears as it should. Is this normal? I’m indicating the correct thickness of material so the focus should be correct.

[lightner]

You most likely have set the material height incorrectly. Please show your work so that someone here can comment.

[Houdini7]

You need to calculate the distance from the top of the material to the laser.
That value needs to be entered EXACTLY.
Off by fractions of a mm will cause the issue you are seeing.

[jbmanning5]

You need to prop the material up so the top is at least equal to the original crumbtray surface.

[cchhun]

Here is a great tutorial on how to calculate the correct thickness.

Cutting Without the Crumb Tray - The NO MATH Edition

There’s a great tutorial here on cutting without the crumb tray when you want to work with thicker material. If you want to know the numbers and theory behind it, go read that first, and then come back. Thank you, @henryhbk! This method uses the digital calipers you should already have, and the not-used-often-enough ZERO button. We’re going to go through the steps from the tutorial above, but without any math or writing down numbers. The first step is to find the height of your crumb tray’s su…

[glen]

Thank you. That was helpful. I had done most of this stuff but I’d assumed (wrongly) that the crumb tray was exactly 1 inch.

I now have it working. Your help was much appreciated.

[rpegg]

Might want to mask the top and do a extremely low power test for positioning. Or some sort of test jig.

[glen]

Given this was for a customer I was quite nervous and did a ‘quick’ test. I was actually more nervous because the material was not my usual plywood. I dialled back the power a little and did a quick test to test the positioning and depth of engrave and when I was happy went ahead with the print.

The artwork isn’t mine but I’m happy with the result. I think the customer will be happy.

On a side note, I keep meaning to put together a post about all the projects we’ve done so far. work keeps me busy but at some point that’ll happen.

[ptodd]

Nice turn out!