Lessons learned the hard way: Proof grade material is not the size on the package

So mother’s day rolled around, and I spun up this gorgeous box for my wife for her photos/scrapbooking stuffs, only to find out the hard way, proof grade walnut is NOT the 3.175mm aka .125 inches the website said but actually is 3.440 aka .135… Inches.
I found this out the hard way, and now my trust issues with proof grade are getting worse because now not only can I not trust the default settings, I can’t even trust the sizing of the wood.

Ending
Up having to use some left over Baltic birch to cut this as I couldn’t use the proof grade that cracked when attempting to accept what should have been a perfect fit. Next time (if there is a next time) I’ll be measuring all thickness before cutting so I don’t waste anything.

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Last year I started a thread asking others to measure the thickness of a Proofgrade thick material because mine was not the size indicated.

I am thinking the wood expands if there is lots of humidity.

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It’s always best to measure, since wood products can vary from lot to lot.

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I follow this rule 100%:
Use “SET FOCUS” everytime.
Everytime. Even with proofgrade.
Use SET FOCUS.
Everytime.

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Not a bad practice, but I think the issue here isn’t focus, but fitting tabs into slots…

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oh man… I misunderstood… I thought they were having it cut or engrave incorrectly
Sorry!

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Oh yeah I’ve ALWAYS had issues with it not cutting the proof grade stuff correctly, I know what speed to set it to to garentee it cuts but it’s incredibly frustrating. And the last time they didn’t even respond when I posted in support about it

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Exactly, because my pattern was made for 3.175 mm aka .125 inch thickness

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So sorry you had problems with it. I’ll bet the whole lot of it was mislabeled, and of course, GF would just expect it to be correct. But at least you were able to compensate and get it done for your wife. The design looks great!

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Many of us have put aside our calipers now that set focus works as it does. However, for tabs and slots and other projects that require precise information measurements must be taken.

On the Glowforge sales page, all of the items thickness is listed as “approximately”. Wood is variable and organic. It swells and warps when humidity levels change. It is the same with wood from other suppliers.

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An email to Support listing mislabeled wood should get the wood replaced. Documenting that even with clean lenses the GOGM does not cut through should get a change in what 100 power is, and proofgrade material replaced. That replacement is the guarantee.

I have had a number of cases where the six inch width of the basswood was critical and measured, only to have that change by as much as a half inch over 24 hours. Walnut is not basswood but change over time is what wood does. I have needle files and fingernail files for that even if only to align the start.

I don’t know when that was, but they’ve stopped doing support via the forum, which could explain it. :slight_smile: PG settings generally work for me, as long as my optics are clean.

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I don’t know that I’ve ever had a piece of medium PG that was .125 - typically it seems to range from .118 to .128 depending on the species. Mostly on the shy side. Draftboard seems to be on the thicker side.

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This has been my experience also.

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To be fair, the website does say approx 1/8" when you purchase it. There has to be some tolerance both ways, although .135" does seem to be on the thick side. I’ve seen some of my maple as thin as .119".

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I don’t have an issue with it not being 1/8" because I can plan around a known thickness. I don’t even mind that the different types are different from each other.

But the variability within a type drives me nuts - I have to either design for a specific sheet (or sheets) of PG or modify the design once I hit the GF. One of the benefits of PG was supposed to be consistency.

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I’m at this point thinking about moving to spoofgrade because that is more consistent than the official PG at this time

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It does not matter what it is at purchase, it will change over time. The specifics will vary by location and season.