Inconsistencies with Proofgrade depth!

And unfortunately the you can’t make any adjustments to the catalog designs.
If it’s possible, someone please share.

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It would be interesting to see if the QR codes are the same. If they are different thicknesses I would hope the codes would be different. Then the whole point of the QR code would really make sense. The glowforge could adjust the settings from batch to batch.

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Actually once purchased you can download the SVG files by using the debugger in your Browser. You could then edit them but it would be a bit tedious.

However if you upload them they seem to lose their auto score / cut settings.

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Every piece of material has its very own QR code. It is even more specific than for each batch. It’s a number that gets associated with material in a database, so what you say would be possible, but not for environmental differences (swelling due to in transit humidity for example).

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All the maple plywood you purchased? That is strange. I’ve been working with the Proofgrade for quite a while and haven’t had an issue. But my latest shipment was in September.

I would imagine it is a bad batch then because the whole ecosystem is built around consistent materials for consistent designs. For their designs to work, the tolerances have to be less than what you measured.

I could image them changing the Proofgrade thickness somewhere along the line but they would have to announce this because so many folks have designs they’ve already downloaded locally or purchased that would suddenly be obsolete. It would be a pretty bad move at this point.

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It wasn’t all of my last order, but seems to be most of it. Really strange.

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I’ve had it happen as well. Are yours all labeled the same (e.g. Medium Maple) or do you have some 1/8" Maple? I noticed that the old stuff (1/8") is different than Medium. If they’re still not all the way through the old stuff now that they’ve switched to the new med/thick sizing.

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If the wood swelled, shouldn’t the 12" side be significantly longer as well? I think it should be, but I’d be happy to be shown why I’m wrong.

If the thickness went from 0.124“ to 0.134“, that would be an increase of ~8%. Some quick internet research says that maple has a “T/R ratio” of 2.1, which I’m understanding to mean that the radial shrinkage (and presumably the expansion) of maple is 2.1 times that of its tangential shrinkage. So, if the thickness expanded by 8% (which IS apparently the amount of radial expansion maple will experience when going from its minimum to maximum moisture content (0 to 30‰)) then the width of the wood should have also expanded by approximately 3.8%.

Is the piece of wood around 12-1/2" wide?

Sites I looked at in my quick research…

http://www.wood-database.com/wood-articles/dimensional-shrinkage/
http://www.thisiscarpentry.com/2010/09/03/moisture-content-wood-movement/
http://owic.oregonstate.edu/wood-shrinkswell-estimator/mobile

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Wood swells differently with the grain than across it. Maybe that’s the difference you’re seeing?

Right. But that only addresses two directions and wood is three dimensional. It seems that it’s typical for wood to swell some amount in X (radially), another similar amount in Y (tangentially) and a tiny bit in Z (um… “axially” maybe). @teditz has observed some wood that is 0.134“ thick when it should be 0.124“ thick. There’s been conjecture that this is due to swelling. If that’s the case, at least one more dimension of the wood should be significantly larger than expected.

Oh wait, we’re talking about “plywood” with an MDF core. The majority of this piece of wood doesn’t even have grain so it’s probably irrelevant.

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I went back out of curiosity and measured a recent project that was a rectangle. The rectangle is one kerf width short. Thinking I was losing my mind, I went to an older project. It measured 0.0015 inches smaller.
So I don’t know anymore. I will continue to measure.

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It is wood then an old project may have changed if the weather was different when it was cut. The kerf is very small compared to the length.

Yes, the kerf on hardwood and plywood is about 0.007 inches per cut. The round hardwood part that is my old project has varied a total of about 0.003 inches since I made it. I have checked it about every three weeks as it is a size check for an ongoing project. Its diameter is 3.250 inches. When I fist cut it, it was exactly to size as measured on my 4 decimal point calipers.
The new project that I just cut shows 0.008 inches short on a 7.2 inch length, when measured with my 4 decimal point calipers.

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You are probably bumping into the accuracy limits of the GF. The exact distance travelled depends on belt tension and backlash, etc and whether you hit cosine belt problems like @jtbarrett.

Thank you for letting us know about this! You should have received an email from us with more information. We’ll look into it.