Laser focus inconsistent

[R-Snodgrass]

I’m having issues with my laser focus being inconsistent specifically when cutting silicone 0.06" thick.

I’ve manually set the focus height and sometimes it cuts perfectly. Many times I have to stop and restart the cut or turn off the machine.

Cleaning the lenses is not the issue.

I’m also manually setting the focus height but it is definitely changing between cuts as you can easily see the cut width being much wider when in error.

It’s now part of my process to have a number of small test cuts in every image in order to stop the cut before it gets to the actual project.

[R-Snodgrass]

I should add that it seems much worse the darker the material (IE:black) though that doesn’t make sense given I manually set the focus.

This could be coincidence as it was cutting black that drove me to writing this.

[R-Snodgrass]

Here is a bad cut left and good cut right.

It appears to be focusing as though it’s a thicker object, I conclude this because a sectioned was on a slope and the hight point had a tight line.

[Jules]

Easiest thing to do would be to put masking on it. (White masking tape…large rolls are pretty cheap.)

The Glowforge records a couple of measurements during it’s process, if they don’t match, it’s possible for the focus to be off. (And it’s hard for the camera to pick up the red focusing laser on dark materials.)

If you want to do it manually, you have to enter the thickness information in the Unknown Materials slot, and then enter the focal point height in each operation in the thumbnail column. That second set of entries will over-ride the auto-focus set by the laser beam. But you have to enter it a lot of times for a lot of operations.

[jbmanning5]

The focus height has to be a different height than the material thickness for it to override auto focus.

So material thickness of .060” and focus height of .059” will override whatever the auto focus is picking up.

It’s also worth cleaning the windows on the bottom of the head. One is a camera and the other is a red diode laser. Both ate used for autofocus and if dirty, you might get inconsistent or bad results.

[R-Snodgrass]

I’ll bank on the auto focus overriding then… I’ve already set the height of material and the individual cuts.

Good to know on the dark material if I’m using auto.

[R-Snodgrass]

For the record… not a fan of this nuance.

[jeremyh]

Since this problem is being seen on materials that were purchased from another company, we can’t offer support for prints that don’t come out as expected. Materials may vary widely from piece to piece, even if they’re created by the same manufacturer. I’m going to move it to Beyond the Manual so other folks here can help. Should this happen with a print on Proofgrade materials, please open a new ticket in Problems and Support and we’ll help you right away!