Pro Shields questions

Hi 'forgers! I work in a public library makerspace and we are considering purchasing a Glowforge Pro. We’ve had a Basic model for over 4 years and sadly it recently bit the dust. I’ve never used a Pro before, and I’m wondering what sort of situations would constitute removing the pro shields? I’ve been reading that if you keep the pro shields on, you’re operating in ‘class 1 laser conditions’ but if you remove them, you’re now in class 4 territory. We are a busy makerspace and children are often using the Glowforge with their parents (and many are at eye level of where the passthrough slot would be.) Are the pro shields removed when your material is over 1/4 inch thick? Thanks!

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The pro shields are removed whenever you need to use the passthrough. They are covering the passthrough slots.


The passthrough slot does not accommodate any material thicker than 1/4". The shields are removed whenever the passthrough is in use.


Ah, I see. And I see now that I misread the safety manual. I was confused about this part:

“When the Pro Shields are removed, the crumb tray is properly installed, all instructions in
the manual and the Glowforge App are followed, and Proofgrade materials are in use, Class
1 conditions exist. The laser operator must prevent children and untrained users from
accessing the Glowforge Pro.”

Why is it that when you are not using proofgrade materials, class 4 conditions exist?


I thought class 4 was from having open areas of the laser, in this case, specifically the passthrough slots. I didn’t think it was material dependent, but specifically a precaution because for laser bed is no longer fully enclosed.

I could be mistaken though.


Maybe this is from unknown conditions from the material you are using, whether it be from fumes or sparks, since the laser wouldn’t be fully enclosed, you’re more at risk to unknowns? Really just guessing right now though.


@CMadok had it exactly right — unsurprising, they’re super smart[1]. Here’s a guide to laser classifications:

  1. “always listen to cmadok” is solid advice all around :slight_smile: ↩︎


Thank you so much @evansd2 for the link, @CMadok for the help, and @dklgood for the clarification! I find it interesting that “The laser operator must prevent children and untrained users from accessing the Glowforge Pro” even when using it under ‘class 1 conditions’ since they are heavily marketed to schools and makerspaces. Am I misinterpreting that?

I would be curious to hear from other educators about this as well and how they handle the Pro with regard to children. We rarely use proofgrade material in our makerspace so it would certainly be a class 4 situation.


How old are the children? As long as you have one laser safety officer present, you should be fine.
You can get the certificate for free through laser sites and I think Glowforge too. It’s a short safety class and then you pass a quiz and get your certificate. I got mine right away, and it’ll run through the safety procedures of a class 4 laser, so you’ll be more informed and prepared in your workshop with how things should be handled.

Are you planning on keeping the shield off all the time? If so, I think you’d need to give kids a required safety lesson prior to allowing them to use the laser or be in its vicinity-for example, don’t run around near it, which is especially important if there are materials sticking out the passthrough slot. Don’t put your fingers or other non-approved items through the passthrough slots, even with the machine off (Besides obvious safety issues while the machine is running, the rubber that covers the slot when the guards are removed can become brittle over time and mine ripped just using it the way it’s intended). Don’t look through the passthrough slots while the machine is running (this goes with not putting stuff in there because in order to look, they’d have to move the rubber seal up)

Personally I’d be more concerned about kids slamming the lid closed or doing something else that would break the glass, and that will be an issue whether you have a basic, plus, or pro. And just make sure they know that any material containing chlorine is off limits (vinyl, PVC, etc). The machine is pretty good as far as operational safety goes, like if someone opens the lid, the machine automatically stops running.

My local library had a pro in the makerspace. They had a rule that children under 8 couldn’t operate the laser without direct parent supervision and the parents and all adult users needed to sign a safety waiver.


In a personal (home) environment, the shields are a non-issue. The laser doesn’t come shooting out of any opening, which the GF doesn’t have in any case. I had to go looking for the shields when I had to ship my first machine back, they had been removed from day zero.

In a public setting, however, you are opening yourself up to legal issues. There still is no danger, but lawyers are always ready to take on a new case…


normally. The risk is mostly from reflections. You’d have to be making a bunch of bad decisions that would lead to real laser danger even with the shields uninstalled, but it’s theoretically possible.

So yeah really low chance of real issues but if you do have them the potential damage is really bad. The class 4 warning is Glowforge being (reasonably) cautious.


I believe that assumption is based upon the size and thickness limits of Proofgrade materials, that being able to fit within the confines of a sealed cabinet (no passthrough in use) and less than 1/4" maximum thickness.

As mentioned, Class 1 lasers are fully contained and operate with no exposure to the user, Class 4 lasers have exposed laser beams, or in the case of Glowforge, an exposure opportunity that exists when the shields are removed, albeit a very minor one.


I think there is excessive lawyer driven protection in any case. With the shields in place it is not different from a basic for most practical considerations. With adults or children I would never want someone using it without supervision. There are too many things that will damage the machine if not paid attention to or known about by the inexperienced user at any age.

There are also many materials that can damage both people and machine so any non proofgrade needs to be checked. Ordinary wood, cast acrylic, and vegetable tanned leather are safe but wood with added material, or non standard leather need scrutiny as to what the added is, and even proofgrade acrylics can destroy a machine if one is careless. Plastics that are not acrylic need to be treated as dangerous until the specifics of its chemistry is known. Even though most rocks are good to engrave that chemistry must also be known and even salt on/in the rock can cause a problem.

If your basic is dead you still might be able to replace it at a discount.


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