Focus height check

My understanding, maybe incorrect, is that when the glowforge head moves to the center of the part and the red laser comes on briefly, the machine is verifying the height of the material compared to what you may have entered.

If this is true, and if you have a part that is not a consistent height, will this throw off the cut? For example, in my photo mat project, I am cutting out the openings for the pictures, removing my masking, and then going back a second time and engraving the captions. So it’s possible that when the machine gets ready to begin the engraving step, it will take its “check measurement” where there is a void in the part. Will this have any effect on the final outcome, if i have already specified the material thickness and focus height when setting up the job?

Even after 16 months of use, I am not 100% sure I understand the laser dot scanning step and how or when it sets focus. There are so many variables in the process. I know that I can override by manually setting my own focus. But yes, if it hits a hole in your material it can cause the focus to be off. Folks have speculated that is no longer the case. Had it happen twice last week. No doubt that the focus was way off. My kerf doubled in size and the cut ended up about halfway through the material. My fault, I saw the laser dot hit the hole. Always watch it.


Would it be possible for you to do an initial caption run at very low power, so that you have a perfect location for it. Then after cutting out the central window, you might leave that in place for the second run, and only remove the masking from the area of the caption ?
John :upside_down_face:


Theory is that if you specify a focus height and it is different than the specified material height, the red dot measurement is ignored and the manual focus height is used instead.

But sometimes it can refuse to print if it can’t see the red dot anyway (error message about material). I haven’t seen that in a while, so maybe they’ve changed the behavior or maybe I’m more careful about having material near the center of my design for the dot to hit.

I’ve seen the material height error in the past week. But it was only a warning because it allowed me to print.