Using the passthrough for thicker materials

So you’re saying that after the machine goes through it’s startup calibration, you can manually move the head to make it think the home position is somewhere else?

Can… but not SHOULD.

The manual expressly warns you against moving the head and gantry manually, because motor = generator, and forced motion on the motors puts charge on your control board where it shouldn’t be.

Also, since it is a manual move, you will abandon all accuracy by doing such a thing, including camera accuracy. So unless you are wanting to cut in the physically possible but programmed out of bounds region (and are willing to risk warranty voiding damage to do so, and abandon all precision of placement), there is no reason to want to do such a thing.


It puts it on the supply rail via the back emf clamping diodes and is completely harmless in my experience. I move my 3D printers frequently with power on or off without any problems. The most that happens is some LEDs light if I move them quickly with the power off.

It would be poor design if the driver could be damaged by the motor acting as a generator. If you disable the drive while the axes are moving you would get the same effect, so simply resetting the controller with an axis in motion would kill the driver.

I agree. I manually move the gantry on my own laser all the time. But, I don’t know the precise design used in the Glowforge, so the manual does say to avoid it, and that there are safety measures in place, but damage remains possible, and so it should not be done.

And since it permanently (until re-calibration) messes up your motion and alignment, there is little practical reason for doing so.

In my case, I had moved the head to try and grab the back rubber flap on the pass through. But eventually realized if you are doing .35" material through the slots it is best to work in reverse.


I didn’t understand that part. I thought the two slots would be mirror images of each other, so both easy in hard out or vice versa. Are you saying it is easier to feed in the back and draw it out the front?

Ever since I saw the rubber sealing strips I feared they would have a ratchet effect.

The slots are (as far as I can tell) the same size. The issue is that when you push from inside the machine to outside of it, the rubber flap goes out the hole with your work piece. If you stick to the 1/4" maximum that Glowforge says is possible, this is not an issue. But when pushing to the absolute limits of the slot, what can be pushed in (only your material is in the slot) cannot be easily pushed out (your material + the rubber is in the slot).

So, you have to remove the rubber flap (I really don’t want to, I frequently strip screws by over-tightening), or you have to lift it out of the way while first pushing the material through the slot. This lifting is essentially impossible on the rear flap, but reasonably easy on the front flap.


I don’t have a pro, but can you potentially push something through the back flap to help you get it to sit on top of the material and then push it through the rest of the way? I’m thinking like thick cardstock or something like that. Something that is rigid enough to push the rubber, and thin enough to be pulled back out easily, leaving the flap on top of your material as you push it through.

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Possible. The flap is very short, pretty heavy, and very flexible, so you would need to get the secondary material to be flush with the top of the work piece as you advance the feed to ensure the rubber winds up on top of the work piece. And with the width of the machine, that would likely mean you need a second person involved in the process.

Pushing from back to front worked reasonably well, and was possible alone.

Mostly… just going to try and minimize the cases in which I attempt 1/3" thick materials long enough to need both slots.


Moved to Beyond the Manual


Looks like the main “using thicker material” post didn’t come over with the responses to it.

But yeah, good call on splitting this out to be more readily located.

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Not that I’m thinking of doing this or even have a use case in mind, but since the front door of the laser opens, is it possible to operate within the focus height parameters on an object that wouldn’t fit in the machine with or without the passthrough slots and still engrave a little something? Albeit recognizing that it may not be a good idea.

I do believe that this has been tested, although official forum guidelines remind us that discussing off-label use that specifically defeats safety features is a flagable offence.

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There are 2 magnets in the door opening that are part of an interlock preventing the machine from operating when the door is open (there are corresponding magnets in the door). That prevents you from opening the front door and putting something thicker than the pass-through into the machine on the bed and running the machine.


Oh no, now I feel bad. I didn’t think about that, though of course it makes sense. It’s so easy to underestimate a machine’s power. I’ve been pretty lucky, save one minor planer issue, another minor table saw incident, and a chisel stab or two. But I do have friends who have lost fingers to table saws and finger nails to routers. I did sew through my finger, nail and all, once. I have a hard time placing the glowforge in my “how afraid should I be” ranking. It certainly seems and feels safe. A good wood working instructor starts the class with a healthy dose of horror stories and I feel like I may be missing the corresponding “laser talk.”


Bypassing safety interlocks generally leads to an “evolution in action” event. :thinking:


I worked around (much smaller) lasers in college, so I got a little of that. There was the guy had put a hole through one of his fingers by having the finger in the beam path when it was turned on. The GF has been engineered to be quite safe when used as directed, which may lead some people to think of it as safe even when abused.

I was probably really lucky to have stepped away about the time of that metal-cutting bandsaw incident in college. :fearful:


:rofl: Another form of natural selection at work…


I gots my suit on, I should be covered.


Not sure I agree with that. I’ve cut off all of those goofy click-tab things on plastic gas cans that prevent you from using it unless you’ve got it tipped and twisted “correctly”. They’re a super PITA especially in a snowstorm when you’re just trying to snowblow the driveway! :frowning_face:

Bet there are more table saws with the kerf splitting blade guard removed than are still on the machine. Yes, there are accidents that might/would be prevented by having them in place but they get in the way of a careful user and those of us who already have been naturally selected a step or two above the “look ma, no hands!” level shouldn’t need to be constrained by the lowest common denominator.


Am I alone when it comes to Darwin. I am so sick of the anti-whatevers. I am so sick of the Lawnmowers with the trip to cut them off. Keep your feed out of the mower…

Life has been so complicated by protecting all of us…

Anyone got a .22 to replace a fuse? I rest my case…