What's the minimum acceptable thickness for Proofgrade medium hardwood?

My current batch of hardwood is much thinner than previous batches. What’s the minimum acceptable thickness for Proofgrade medium hardwood?

AKA How thin would it need to be for :glowforge: to replace it?

How thin is your hardwood?

There is no “minimum” - it’s all “nominal” size. In fact, you won’t find a precise size specified. That’s why it’s “Medium” and “Thick” - about 3mm and 6mm / 1/8" and 1/4".

Even single sheets can have significant variance across them - all materials, not singling out proofgrade.

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Because I’m curious, I just picked up my stack of “medium” PG hardwood and also what’s sold as1/8" at Rockler. Cherry, Oak, Maple, Walnut, Poplar, and a bunch of exotics.

The PG is all masked, which adds around .15mm (sorry, I use metric mostly), and it varied from 3.11-3.91, so subtract masking and it’s 2.96-3.76. I also checked some of the larger scraps I’ve saved and one piece of Cherry (no masking) was 2.91.

The Rockler stuff, which is unmasked, varied from 2.54-3.74 (again, all sold as 1/8).

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There’s gotta be a point where it would be deemed “too thin” or “outside of spec” from Glowforge support, that’s what I’m asking.

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Well phooey I think my cheap calipers are dead. Will have to wait a few days to replace them and properly measure.

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Hi @thejambi thank you for letting us know about this.

Could you please send a photo of the Proofgrade you mentioned? If you have calipers or another accurate way to measure, please include measurements of the material thickness. If you have another sheet to use as a comparison, that can be helpful, too.

So above in the comments, someone reported their medium hardwood thickness lowest range being 2.96mm (0.117") unmasked. I’m seeing 0.097" for the unmasked thickness of the cherry hardwood from a sample cut from my recent batch.

I’ve had some thin boards here and there, but I’ve just ignored them as they were rare. This time around, it’s all more than 10 pieces of cherry hardwood I got, it seems. Here is a picture of one of them, it clocks in at 0.104" thick with masking. A medium walnut hardwood board I have is 0.134" with masking.

Please let me know what you’d consider “too thin”, I’d appreciate it so I know what to expect. Thanks!