Question about measuring material thickness

I’m going to cut an acrylic sheet I’ve never used before, so I’ll run a test on it first for engrave/cut. When I measure the thickness (with my accurate but not-precise calipers), it wavered between 0.06" and 0.07".

If I hold gentle pressure on the jaws, it reads the lesser number, but when I let go it reads the higher number. I’ve had this happen where I went with the lesser, and didn’t get a clean cut (had to run a 2nd cut). Should I just default to the highest reading from now on, or improve my technique? Or just take the average of the two? [I can be a slow learner some days.]

I take at least 3 sample readings on each new piece.

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The cut is not that sensitive to focus height to where 0.01" will make a difference. Power and speed have much more of an impact on cut quality than focus height (within limits, obviously.) The auto focus is nowhere near that precise.

For thicker materials, you can focus much lower than the surface of the material for the “straightest” kerf, although most people just use surface height. For something as thin as you are using, it won’t make any difference.

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Seconded on everything @eflyguy said.

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For basic cutting, I find it better to let the GF autofocus. If you are concerned about a specific portion of your print, use the “Set Focus” tool (under the 3-dots icon in the toolbar) and click on the area of concern.

If you are going for a defocused engrave, score, or cut, the manual focus is the way to go, otherwise, I’d let the GF drive.

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Heh, I go the other way here, I set my focus manually on almost everything. The UI is so confusing, it’s really hard to tell what it’s doing otherwise… can I override the auto focus height in cut settings? How do I know? What actual height is it doing?

I think the auto height stuff is too dumbed down, and the UI doesn’t have enough info density to make me comfortable with it. I really wish they’d put some effort into improving it.

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I Set Focus on everything unless it’s a material and file I used a lot.

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Since you’re using set focus and cutting I don’t think it practically matters what the material height is. Focus on tuning speed and power. There are a lot of great testing files in the forum if you want to get really nitty gritty. For something simple like this I just set three small circles at full power and different speed increments.

I do a test on every new material I use. Unfortunately, the tests don’t accurately reflect the details of my work. I usually have to tweak after the first sample has been created (and that’s after I’ve run the test).

One oddball thing today is that I’m cutting 5 separate pieces of the same file. They are big enough they each have to be on their own board of HDF. First two dropped out of their waste material w/no problem. The third was just connected enough that I had to crack the waste material to get the project piece out. I wonder if it’s humidity? It’s a wet day outside–I keep the external fan running to prevent moist air from getting into the GF from the outside in between jobs.

Materials can be inconsistent, even Proof Grade. Acrylic is well documented to vary significantly across a single sheet. One thing you can do is check that things cut completely before moving them, run the cut again on anything that isn’t. GF will cut in the same spot as long as art and material haven’t been moved. People use tape, xacto knife, picks, etc to try to lift cut pieces without disturbing the waste material.

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Yep, the high-tack masking tape I got by mistake is perfect for this.