Yesterday, I started a 7-hour-long engraving on PF thick acrylic. It went through at least the first five hours fine. Around hour 6 I smell smoke and come out to this. The laser tube exploded out of the lid? I don’t even know. Help?!
This is terrifying to me…I have had a GF for 2 days.
Ive had mine for a year. I was a Kickstarter. It’s been great right up until today.
1 Like
Are you okay? Sorry that happened. It looks like the tube is still intact on the carriage? Its hard to tell what exploded? Could it have been a temp issue with the internal temp getting hot with hours of constant running and the exterior air on the vent tube being too cold and shattering the lid glass? I am just spit balling here. Again I hope that your okay.
That’s disturbing. Glad nothing but the GF was seemingly harmed!
Looks like the acrylic caught fire. The laser tube is intact, but covered in thick soot.
Were you using the PF settings or manual settings? Anything under the acrylic? There have been a couple of events like this with acrylic, but they have all used manual settings at a higher power than PF, IIRC.
Possibly, your air assist fan stopped working or stopped moving a lot of air? Forensics will be difficult, sadly.
3 Likes
ugh. that sucks.
where were you monitoring it from? were you watching on a camera remotely? acrylic can catch on fire. obviously a 7 hour engrave is a really long job to stay with the machine, but you really do need to monitor the machine. if it catches fire and you don’t notice…
one thing i will warn everyone else who is seeing this photo: pretty much every picture you see of the GF (and other laser cutters) that get heavily damaged or destroyed by fire happen when the user is in another room and don’t catch the flare up / flames quickly enough.
9 Likes
The tube appears to still be intact, so more than likely what you heard was the lid shattering.
Clearly I’m not the expert here, but It actually looks like a fire to me. We’ve seen others just like this. Hope everybody is ok
2 Likes
I’m fine, and the house is fine, thank you. The explosion seemed to have been somewhat violent, given the distance it threw glass. But the laptop next to the machine and wood/fabric stock for cutting are all fine. No smoke marks on the wall, so I don’t think there were big flames. But the laser tube is certainly unhappy.
I don’t even know enough to spitball. Hopefully the GF folks have logs and pics.
I was using the PF settings for a 3D engrave, except that I set it to do three passes instead of 2. The piece was on the standard honeycomb tray.
Been doing a lot of work lately with 3D engraves, and i’d hazard a guess that that third pass you programmed probably set fire to the acrylic. What happens if an engraving pass cuts all the way through thick acrylic is that additional air feeds to the flame from underneath the material, and since the laser beam is moving over and over in the same area with an engraving run…things can get extremely torchy. I’ve seen it in very small spots and it always damages the piece beyond use.
(For 3D engraving on thick acrylic, two passes is enough. The default setting has a high LPI to start with.)
So that, and walking away from it, probably caused the acrylic to catch fire, and the heat popped the safety glass. Shame you weren’t there to stop it in time, but at least the damage was limited to the machine, which is how they designed it.
I’d count it as a lucky thing, so I’m happy there wasn’t any more damage to your home. They’ll be by to discuss next steps soon. Good luck! 
9 Likes
Well, my walking away didn’t cause the acrylic to catch fire, but it’s possible I could have caught it in time. I accept my responsibility for not being sufficiently diligent. I’m very sad about this; I’ve loved using the machine for the past year.
I’ve used these same settings on prior projects, and the third pass doesn’t come close to going all the way through the acrylic. FWIW, I was making a fabric stamp, and the extra “height” for the positive section of the stamp is useful. But I agree with you and other that an internal fire and heat build-up is the most likely explanation.
1 Like
Well, they’ll get something worked out with you either way…I’ve never known them to not do it, so aside from the extreme hassle, you’ll probably be back in business soon. I do hate to see things like this happen, but the fire was contained, and that’s what the machines were designed to do. It’s actually very lucky all around.
Hang in there.
1 Like
Most of our catastrophic fires have been acrylic. I didn’t know the hazard early on, I’m just lucky that others have found this not me.
At this point, I’d think it prudent for 
to add a popup warning anytime acrylic is used.
Bottom line though is we are literally playing with fire and have a responsibility to keep an eye on our machines when they are running.
3 Likes
Tempered safety glass is like that. When it decides to go, even if it’s from a tiny tap in just the wrong place, BOOM! Glass flies everywhere.
2 Likes
Thanks, Jules. And I agree, on balance I got very lucky indeed. We will rebuild!
I had no idea that acrylic was particularly risky. In the future I’ll try more, smaller steps yo make monitoring more practical.
5 Likes
That’s the spirit I like to see! 
(Good for you…i think you’ll succeed quite well.)
Every fire I’ve seen reported on these things (so far) has happened on thick acrylic or foam. So yeah, I watch those like a hawk. There’s a little camera setup that has worked really well for me that works with an iPhone. If i have to take a potty break or something, it goes along with me.
Of course now, we can Pause the print and it will resume where you left it off as long as you don’t turn off the machine, so that will come in handy for long jobs in the future.
4 Likes
Wow! That does not appear to be a pro model. I thought I read somewhere there is some advisory to not run a model, that is not the pro model, for more than a couple hours continuously.
I don’t recall ever seeing anything along those lines, at least not anything official. The machine will pause for cooling if it needs to. (There are controls in place to keep the tube from overheating through use. The machine will just pause if it needs to cool off.)
3 Likes
It’s a basic model; I don’t recall run-time warnings either. The machine definitely gave itself breaks when I was running it in July 
Also, @GrooveStranger makes a good point about the safety glass. That’s what did the exploding, as it’s meant to do.
That may be an assumption on my part based on the Glowforge ad for the pro model. The pro model features upgraded solid-state cooling that allows nonstop printing all day long. But I still thought I read somewhere in Glowforge literature to not run the other models for not more than like 4 hours continuously. But I am new to Glowforge, and checked out a lot of brands and models before making my purchase. May have it mixed up with something else.