Need Proofgrade for accurate alignment results?

They currently use the red laser and the head camera to make a single height measurement for auto focus, but that is done after you have placed your design and pressed print.

Yes. I’m thinking the red laser may be good enough to focus the CO2 laser, but not accurate enough to be helpful with the lid camera adjustment.

I’m anxious for their staff to return from the factory, so they can get back on task with software development.

I’m hoping production gets streamlined enough when my day 22 order is delivered that we will start to see some focus shifted back to software development.

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The quoted spec for the surface measurement is 0.1mm which should be good enough. Who knows if that is currently what they achieve?

A simple set of nice digital calipers should fix this problem.

I have to disagree with your disagreement. :wink: If the implication that the most accurate alignment could be achieved by only proofgrade material, the list would consist of,

  • scrap your non-PG material and use PG

The very mention of entering height for non-PG material negates the premise that PG is mandatory for best alignment results. In fact, they should probably go a step further and mention “exact height as measured by digital or mechanical calipers.” Just because most of us are measuring using calipers to get within a few .000” doesn’t mean that all are. Guarantee some are measuring with a ruler or even just guesstimating.

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Putting all else aside, I don’t find the statement out of line with common practices. For example:

To get the best results, use one of the Hewlett-Packard papers, which were developed especially for HP inks and your printer.

I’m not picking on HP or anything. You’ll find similar everywhere.

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Yes but we are only talking about alignment. You could argue the end result might be better with PG as it is good quality material but alignment shouldn’t be any better.

BTW are there laws about false advertising in the USA? It is illegal in the UK to make false claims about products that don’t stand up to scrutiny.

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Yes, but in practice the FTC only really goes after certain categories of misleading or false claims.

Also, the First Amendment to our Constitution provides for quite a bit of leeway.

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Unfortunately the red laser is also not parallel with the IR laser (by design). The red laser fires down at an angle. This means the XY offset of the red laser’s spot and the IR laser’s spot will vary depending on material height. Of course, the position of the red laser’s spot will also vary within the head camera’s FOV, and this variance is what is used to calculate material height.

I think this is the case, a similar post I made a while ago got a reply of “correct” from Dan.

Though, I suppose once the material height is determined (by sensing the XY offset between the two spots) the red laser spot could be used for positioning on flat materials, the software would just have to use that offset to calculate the true position of the head.

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Yeah i had to deal with that recently on a Facebook Page where someone was trying to claim that the Glowforge would ONLY cut Proofgrade thus Glowforge is a scam Q.E.D.

It did not take much to set them straight, but the perception is already out there

The other issue ,as @palmercr pointed out… buying Proofgrade is unlikely to be an option for us Internationals due to the high shipping & time costs. Until they set up regional distributors this is likely to affect International uptake.

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I concur. While it is fine for Glowforge to flog their own product to enhance alignment and settings, even giving it priority, wording might be best that allows that you can get just as good of a result from properly measured material that is of a consistent thickness. I don’t see that their wording disallows this.

How about:

Accurate alignment requires the accurate measurement of the thickness of material.

  • Proofgrade materials offers excellent consistency in material thickness and does the measuring for you.
  • Manual entry of non-Proofgrade material thickness measured with an accurate measuring device.

but it’s too wordy. Fine as it is Glowforge has it, but could be interpreted that non-Proofgrade is for wannabees.

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The bullet list is clearly a logical OR since the first bullet is with proofgrade and the second is without proofgrade.

All the proofgrade is doing here is automatically entering a pre-measured thickness, which eliminates user error both in the measurement and entry of thickness.

Nothing to see here. These aren’t the droids you’re looking for. Move along.

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The bullet list is not clearly a logical OR because all the other items are things you should do as well. That is why I suggest combining the first two with an explicit or and emphasizing that it should be measured thickness.

  • Use Proofgrade materials or enter the measured thickness of the material if it’s not Proofgrade

It might be less prone to user error but that is not the same as saying “For the most accurate alignment results use Proofgrade materials”. That is a falsehood unless the machine treats a user entered thickness different from the barcode one. I can measure thickness to a resolution of 1um.

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I’m sorry… I mistyped. I should have said “The first two items of the bullet list are clearly a logical OR.”

It is a logical fallacy to read those two lines and think that Proofgrade will be more accurate than accurately measured and correctly entered thickness. Please don’t continue with such a pedantic and false reading.

Lollers.

Those two completely separate bullet points? Yeah, they’re part of one statement that has an “or” between it. You don’t see the “or”? Well, better go get your logic centers checked then because we all see the “or”.

Is there an “or” between the other separate bullet points you ask. No, of course not, those separate bullet points are separate statements.

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This makes sense. However, it also knows where it is hitting the material after doing the focus adjustment.
The problem is, it appears the Red laser is only used just prior to the job starting, and for some reason they haven’t used it to assist in Lid camera alignment Workpiece height calibration or any other pre-job functionality.

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Is it more an issue of consistency (of materials) than one of accuracy?

If Glowforge knows how a material responds in the GF :glowforge:, then determining hardware/software issues have a consistent baseline.

This is it. Thats why i said a good pair of digital calipers should fix all of these issues for anyone

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Thank you for the feedback and discussion – we’ll consider it!

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