Getting around auto focus override glitch?

How do I get around the auto focus override glitch?

Specifically where the machine ignores the material thickness & manual focus if it’s too close to the auto focus reading?

My laser consistently cuts very poorly on all dark materials and I’d prefer not to mask the entire surface with masking tape every time. Keep in mind the same settings for the same material (but brighter color) will cut consistently every time.

The laser (IMO) should not even run the auto focus before cutting if I’ve manually set it for each cut.

I now have to build into each cut a series of bogus cuts just to see if the dang thing is going rogue.

Just set one of them to be 0.01" or so different from the other.

The laser (IMO) should not even run the auto focus before cutting if I’ve manually set it for each cut.

Absolutely correct. Causes a blood pressure spike every time I click the PRINT button!

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I’ve tried that and still not consistent… I’ll try more. This is a terrible flaw.

Edit It still won’t come close to focusing correctly when the material thickness is set to 0.06 and the cut height is 0.058.

What if you use set focus instead? Just mask a small section to focus the red dot on?

I’ll try that, good suggestion.

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That sounds like a different problem unrelated to respecting your manual Focus. Unless your system acts different than everyone else’s and how it’s intended to work. While it will still do the scan, it should always respect your inputted focus height if that value is different than the material height.

If you are getting varying results (out of focus with manual focus height), it could be a mechanical focus problem with the lens, material not consistent, or something with the crumbtray giving varying material height (distance from lens)

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Thank you all for your help.

I kept lowering the focus height as I had suspicions that it was focusing much higher up, this appears correct.
Ultimately I’ve gotten the best, as well as consistent, performance at a focus height of 0.00 and thickness to 0.059. I does appear that if I could focus at a negative height (perhaps I can) it would actually improve a bit more. I’ll look into fake cutting without a crumb tray tomorrow.

I did try doing the set focus on a piece of tape (verifying each time) before every test cut as I lowered the focus. I can’t say if it helped in any way or not as I’ve not tried without it. I ran out of time and beggars can’t be choosers tonight.

As for it having a mechanical issue… it may that and it may be isolated to small thicknesses (less than 1/8") because it cuts 1/8" acrylic perfectly every time and I’ve run hundreds of new plates through it.

Can you throw an example picture up of what your cutting lines look like?

If it’s cutting 1/8” perfect though and not anything thinner, it definitely sounds mechanical to me.