Warning THICKNESS warning

This is the first time I have gotten this error , been cutting the same stuff for over a year now without any problems .

Im getting this material thickness error. As no now I can no longer use the machine.


I read something about some RED DOT that i have to trick , but I dont get it

Please help : This Material Thickness Error is not right !

The red dot is the laser measure of the height of your material. Sometimes it doesn’t land on your material and therefore isn’t measuring what you’re actually cutting/etching. If you watch while using set focus, I think you can see where the dot lands. Either move your project or use another piece of material that’s the same height to where the laser dot is measuring.

I do wish that the GF would use your design to place the dot as close as possible to where the etching/cutting is happening so at least it hits the material.


It does. Not sure how ignored components impact the possible placement, but it does use your design as a guide.

It’s accurate enough on a cut-only file that it will measure right on the cut actually (if it’s already been cut, that is).

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Hmmm. I have definitely had it fall off my material on occasion. Maybe it has changed over time? I’m rarely cutting on small scraps of material so it’s not typically an issue anyway.

I am just cutting a 10 inch circle on soft .5 foam as I have been for the last year , so your saying i have to make square material to cover the red dot and than cut the circle.?

I’m saying you should set everything up and when you press “set focus” look to see where the red dot is falling. If it’s on your material and your material is the correct height, something else is wrong. If the dot isn’t landing on your material, you need to find a way to get the red dot to land on something that’s the correct height.

Ok so that set focus is new to me , have not seen that before, what is the purpose of that to control where the red dot goes ?

When you’re working at the height thresholds like that, any deviation in material tolerances, stuff in the crumbtray divots, warped material, etc can all push you above the threshold.

You can override the autofocus by setting a manual focus height that differs from the material height that you put in, but if it’s reading that the material is too tall, you’d better be real sure it’s not going to catch on the air assist fan.


ohhhhh, ohhh how do i set the manual, maybe that is the answer how do it do that, Thank you.

Set focus is brand new and is amazing. And apparently my brain is not yet on today, because, yeah, you decide where to set the focus so the “red dot” shouldn’t be an issue. :slight_smile:

But @jbmanning5 is right. I’m assuming you KNOW your material is the right height, but that’s far more important than anything else.


If i put in my own thickness level is that setting the manual focus. ?

Maybe if i understood how the red dot measure depth, does it shoot a beam and measure the bounce ? Nothing says manual focus just put in your depth which i have been doing for a year. 0.5 clears fan fine.

First thing…measure the thickness of the foam, unscrunched, with calipers. Just check it to make sure it is less than 0.5" tall. (Don’t try to cut it on the tray if it is over 0.5" tall. Period. It’s possible you got a slightly thicker batch of the foam. That warning, and the shut down, is a safety measure to keep fires from happening.)

Having said that… it is possible that you got the warning in error. That can happen if the foam is dark colored. Try placing some white masking tape over the spot where you use the Set Focus tool so that the red dot can be seen by the camera. (Set Focus, and auto-reading, don’t work really well on dark materials.)

Things have changed quite a bit with recent upgrades to the system. The Set Focus tool was announced here:


at what point in the stages will i see the red dot ?

the problem I have now is that its becoming hit or miss, sometimes it makes the cut others times i get that error message,

Is there a way to trick it by pulling the material out after its set up. ?

Nope - it takes an auto-reading now. Can’t fool it.

What has to happen is the red dot, which moves out (rapidly) to take a reading after you hit Set Focus, has to fall on the material (not off to the side if there is a cutout or something in the material). And the camera has to see it to do it’s calculations, so dark material can interfere with the visuals.

The red dot is located slightly off center of the laser beam…mine falls about a quarter of an inch to the left of the laser, but it can vary from machine to machine I think. Others have said it falls to the right.

It only happens for a split second, you have to be standing at the front of the machine and watching the bed underneath the laser head to see it. But just send a few Set Focuses (Refresh the screen in between) and watch to see where it is going to hit. You can get pretty close at estimating how far off it is, then just select a point slightly left or right to make sure that it’s going to land on the material.

Or if you get an error, and you are trying to cut near a cutout, just click a little further over to the side when you run the Set Focus again.


I waited as long as I could , i had to get the job done,

I had to fool it !

I put a pice exactly 0.3 of material and got the Ok to print , I hacked the door to remain open using the magnet system.

Once I got the Ok to print I switched the material out back to the 0.5 and got the thing to cut.

I think its got some bugs as I am using the darker material , jet black, With your help I got it to work for now. ugh.

Thanks again jules.

I’m glad to hear you were able to resolve it for that job, @coalakida. If you’re still running into trouble with this, could you please let me know the time and date this most recently occurred (if you can’t remember the exact time, please estimate), including time zone? I’d like to take a look at the logs from those print attempts to see what may have occurred.

Thank you.

It’s been a little while since I’ve seen any replies on this thread so I’m going to close it. If you still need help with this please either start a new thread or email support@glowforge.com.