Camera Focus Question Z axis

I have read a few posts and find the info a little confusing regarding focal points and Z axis.

Ive read that LB recommend focusing the camera on the top of the piece during calibration which is fine but what about the difference in Z height (distance) when cutting or Etching as the focal point of the laser stays constant in both modes the height (distance) of the bed will differ thus the Visual focal point changes…

How is this circumvented?

What I do is move the bed so the top of the piece is where I calibrated the focus at. Then I move the bed so the piece is the right distance from the piece for either cutting or engraving. I’m lazy and never changed the focus height after changing a lens, so I place my part @ .5" from the nozzle to place the work in LB, and then move down to .75" to engrave and cut.

You could always move your table towards the laser 1/2 of the material thickness so your focus is roughly in the middle.

Maybe I’m not understanding what you mean though.

I get you, but wouldn’t this void the point of the camera for accuracy?

I.E lets say you have a etched border 5mm wide making a square then at a later date you want to cut around that border and then add another etching within the border etch which touches the border.

if you align the cut line on the camera to be exactly on the outer edge of the etched border but then raise the bed (to the lasers cutting focal point) the cut will now bi bigger than it was when aligned on the camera view.

Hope that makes sense.

Edit: This is wrecking my head :slight_smile: I think what you said is correct and my example makes no sense (or does it) :slight_smile:

It may be bigger in Lightburn, but your laser (hopefully) only shoots directly downward. So theoretically you can pull it away or put it as close as you want, and the line should be in the right place still, just your dot size on the material will be smaller or larger, depending.

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so to clarify,

you have 3 gauges?
One for camera focal placement (based on original calibration setup)
One for medium distance laser to top of material (for etch)
One for smaller distance laser to top of material (for cutting)

Personally I have a stepped gauge with measurements in 1/8ths of an inch. I just know which measurements to use for which application.

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yeah I get you now, so we basically treat the initial placement of the material for camera alignment as if it were another laser method, then after all is aligned use depth gauge to lower/raise for the cut process (cut or etch)

makes sense now :slight_smile:

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Yep, that’s what I do. You’ll find out real quick if your laser isn’t coming out straight. (Mine is angled, but I struggle with chinese crap, and my customer base doesn’t have the same eye for these things that I do, so I get away with being a bit lazy.)

I know mines dead straight.
I actually dismantled part of the housing (frame of laser tube) last year as it wasn’t true in alignment to the rails in both height and squareness I then realigned all my mirrors in height also as they sat on different levels, this made alignment so much more accurate.
i can fire a dot close up to tip then move bed far down and refire and dots are on top of each other.

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