Yep! A piece of tape would work. 
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both work, I learned my lesson with all the settings on the pRu’s being wonky now I always hold the scrap so nothing moves and lift if it is not for sure it cut through. As @Jules said, a second pass will get it every time as long as nothing has moved.
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Blue tape is my go-to cut tester. I just had a sheet of maple ply where 3 of 15 cuts didn’t make it through. Slowing cut speed by 15 has prevented additional partial cuts.
Btw, I’ve had success when I’ve moved the entire piece by placing a scrap of masking over the oopsie and running the cut as a score @ minimum power. Once I’ve lined then back up, I take the power back up and re-cut.
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Ive found the best test is just to see if the piece jiggles around while holding the large part down with your other hand to prevent moving. This way if it hasnt cut through, just run it again with a lighter setting.
I keep a magnet that holds a couple of needles next to my forge which I use to shift around the cut pieces or pry them out.
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I assuming that one of the values of proofgrade is the automatic settings. If it doesn’t cut right, they should give you another one. No?
Also, didn’t I read somewhere that the camera will take warping into effect? Does that come with a later update?
Thanks
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You mean this from the June email? The warranty is a quick read.
New: Proofgrade™ warranty
We have another new announcement: Proofgrade materials are covered under a Glowforge limited warranty as well. This means that your $150 bonus pack of Proofgrade and any other Proofgrade materials you buy (for example, with you gift certificates) are covered too.
We’ve sourced the highest quality materials for our Proofgrade line, so we feel confident backing your materials up with this additional guarantee.
You can read the details at https://glowforge.com/warranty.
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No indication that there is a defect in the material or material workmanship. So wouldn’t count on a replacement. Usually it is caused by slight warping, dirty lens, etc. Not saying that is the issue, just that it’s not necessarily or likely to be a material defect.
And no the camera does not yet take into account slight warping of the material or other curvatures.
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It’s interesting. The warranty clearly states ‘defects in materials and workmanship’ and nothing else is warrantied. But in doing a wider search I found some non-staff posts that give the impression that Proofgrade is guaranteed to work. So it’s not surprising that one can get the idea that the warranty covers the cutting of Proofgrade as well. Which isn’t true. But it does bring up a question: If the material is flat, and the Glowforge is new (i.e. the tube’s power hasn’t degraded from use), then why wouldn’t non-cut-through be an indication of a material defect?
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Not sure that’s really the case. But even if it were, I don’t want to have to wait. If I’m cutting something critical that I don’t want to potentially have to do a double pass after the first one (and suffer the wider kerf and additional charring that creates), I switch it to a manual cut and drop the speed by 10% (so on PG cherry ply for example that’s 163 speed units by default and I’ll drop it to 150 before hitting Print).
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Right - I don’t think it’s necessarily an issue with the material. I think it’s more a function of @staff still fine tuning proofgrade cut/engrave/score settings on both Basic & Pro models. My guess is that they are trying to bump up speed of cuts on the pro models, but might have been a bit too aggressive resulting in partial cuts.
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It’s a balancing act. The faster you cut it, the smaller the kerf you wind up with, and the current Proofgrade settings create a very minuscule kerf. Almost non-existent.
And this is a natural material, there are always slight variations in material, so you have to expect that too.
For those of you who are worried about being out the money for a bad cut, yes they will replace the material if there is a defect in it, but frankly it’s just not worth the hassle. It makes much more sense to just send a second cut, then you don’t have to worry about filling out warranty information, waiting to get approval on the claim, and waiting another week to get another sheet of material shipped out to you.
One process takes five minutes, the other process takes ten days. How much is your time worth?
(And try the pick, or tape, or jiggling. Whichever one you like. They are methods that work.)
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The one I did last night was about 3/4 of a sheet of PG Cherry 
It was my last sheet of cherry so there wasn’t a chance for a second cut. I used the 10% slower setting instead of doing the first and maybe needing a second.
It’s definitely not worth the hassle of a return.
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This feels like a dangerous thing to say without qualifying.
Proofgrade is very high quality material, but it is not magic. The minimum kerf is right around .008" which sounds minuscule, but If you are trying to get two things to fit together tightly, it is still too big.
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And to add to the hassle list: the user has to pay shipping both ways on Proofgrade warranty claims.
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Correct. For tight fit I still adjust for kerf. When glue is okay then I don’t bother.
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You’re quite right - that was a subjective statement. My bad. 
Since the settings on the last update were made available to all of us and I’ve tested them on the PRU, I’ve noticed a much tighter fit due to the currently created kerf on Proofgrade materials. BUT, it is based on a PreRelease unit so I have no idea if the same holds true with the Production units. So everybody ignore that statement.
Thanks!
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Either the PG material varies more than GF thought or the Glowforge varies more than they thought, or the concept is flawed. In either case it isn’t user error so either the PG or the GF should be refunded.
Sorry to hear things didn’t turn out right, I have a few quick questions for you.
Can you let me know the date and time of the print?
Which type of Proofgrade maple were you using, hardwood or plywood? Have you had similar issues with any other types of Proofgrade material?
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I’m getting much tighter kerfs on PG maple plywood, but combine that with material warp and I’m basically just using custom settings for everything on maple ply. I’d suspect the dry desert climate here is not playing nice, here’s a shot of an un-used sheet of PG maple ply, been here about 8-10 weeks (it’s the Starter Kit material). That’s a 1" wide roll of masking tape for reference. Now I can’t say that the wire steel shelving I’m storing materials on is completely flat, but it’s not 1/2" out either, and it does sit with all 4 feet contacting the supporting surface so I know it’s not racked out.
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Looks good, is that at the widest point or the narrowest point?
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