Fire risk

qa

#1

I’ve been looking into laser cutters for a while. I’ve read though tons of forum posts and discussions trying to become as informed as possible about the capabilities and the risks associated with laser cutters. One of the major hazards is fire inside the machine. Most of the materials that can be cut with a co2 laser cutter are at least some what flamible and when mixed with a laser there is an obvious fire potential.
My concern is that all of the reasonably high powered machines I’ve seen have metal enclosures which provides some amount of protection to the machine and enviroment. The GF housing appears to be plastic. With a plastic housing it seems that even a small fire could do significant damage to the structure of the machine, depending on how its constructed, and worst case the whole thing could go up. I don’t mean to be alarmist, but we are talking about a bringing a pretty serious price of equipment into a home environment.

I’d like to get GF’s take on this and any innovative saftey measures that may be in the works.

Thanks


#2

Thanks so much for the thoughtful note. It’s something I worry about too, as I’ve had a giant industrial laser in my garage for a year or more.

I’ll start at the end: Don’t leave Glowforge unattended during prints. It’s unlikely anything will need your attention, but if it does, you should be nearby.

That said, the design was created from plastic that softens rather than ignites, and as you probably saw, the lid is a very solid piece of glass. It’s designed to fail in a way that does not spread any fire.

We’ve also added a number of safety systems to avoid all the major causes of fires we’ve seen in laser postmortems. For example, we won’t leave the head blowing air on the ember left from a cut - we shut off the air when the cut is done, unlike most systems. As another example, we can detect the collisions that are usually the start of a problem with our onboard accelerometers.

This isn’t something I’d let a child use unattended, but I worry about it less than, say, my blender when they’re around.

–dan


Plastic Body and Fireproofing
How flame resistant is the tray/bed of the Glowforge?
#3

“but I worry about it less than, say, my blender when they’re around”

This made me smile as my son as an unusual fascination with our blender… and probably will with our Glowforge as well.


#4

This is the first laser cutter I’ve seen without an Emergency Stop button on it. They’re so ubiquitous, I assumed they were required by code (in addition to being a good idea). Is there a kill switch somewhere?


#5

The button on the stop pauses it while running - unlike an e-stop, though, you can resume. There’s a power switch on the back. Lifting the lid also cuts all power to the laser immediately.


Print button to pause a print? -- It's in the hopper
#6

@dan Is it safe to assume that lifting the lid would cut power to the laser on both the pro and basic models? I ask because I know that the class IV laser in the pro is able to operate with the pass-through slot open, so I just wanted to confirm that it still had the same safety feature in the lid.


#7

OSHA requires a Class IV laser to have a master key interlock and eye protection. I believe EU requires an e-stop on cutters…so EU buyers might want to look into that before attempting to import and setup a GF anywhere it might be inspected. In the US, Federal Laser Product Performance Standards DO require an e-stop for Class 3b and 4 lasers:

“Every commercial Class 3b and Class 4 laser sold in the United States shall include a remote electrical interlock connection. The connection will have two terminals that need to be electrically shorted to each other. If the circuit opens, the laser will not emit a laser radiation hazard above the MPE threshold. The manufacturer is given leeway in choosing the method to be employed to accomplish this task. The manufacturer may use an electro-mechanical shutter or electro-optic modulator behind the laser housing, or they may choose to electrically shut down the power supply to the laser. The only real constraint is the fact that the device must be fail-safe and the voltage used for this remote interlock circuit shall be less than 130 volts RMS.”

If the pause button on the GF relies on firmware to shut down the laser it certainly isn’t failsafe.


#8

@jpshupe Class V lasers do require a master key interlock. However, it’s up to you to make sure it’s compliant if you’re putting it anywhere it might be inspected.

@Chsmith In 2 years of heavy usage we’ve had only 1 small laser fire. It was due to a user who failed to clean out the bottom of the case between jobs that were producing a lot of small paper bits falling through the honeycomb cutting bed. Those bits of paper accumulated and were heated up by the unfocused laser enough to combust. The user immediately noticed the fire and put it out. Keep your case clean, avoid combustible plastics like HDPE and never ever ever leave it cutting unattended and you should be OK under normal operating conditions.


#9

Has anyone attempted a nitrogen or CO2 blanket to prevent the possibility of ignition? I realize, of course, that this suggests the presence of a compressed gas cylinder nearby. Just curious.

I’ve yet to use a laser cutter, so am unsure of just how much risk is to be expected. For instance, when cutting paper, does it always just cut and never flare up? Perhaps a noob question, but certainly a topic I’m pondering while excitedly waiting for the hardware…


#10

With an inert gas blanket, won’t you also have to worry about asphyxiation by oxygen deprivation? I suspect that the ventilation rate necessary to remove the smoke from the chamber would make an inert purge pretty expensive.


#11

Paper is fairly minimal risk, since you vaporize everything in the beam almost instantly, and no energy transfers to the remaining paper outside of the beam anymore.

Running at a lower power that cannot vaporize the paper instantly, or having a thermally conductive material immediately behind the paper can of course change the story. Or I suppose running a ton of layers of paper, which would boil down to the first issue (power insufficient to obliterate) from a different angle.


#12

For what it’s worth, the giant E-Stop button on our makerspace’s 80w Rabbit takes longer to stop a job than the tiny recessed stop button… Hard to believe, but we made a number of timed tests to convince ourselves.

I’m not worried about this issue per se, but I always have both a smoke alarm & fire extinguisher in my home workshop, plus every floor of my house. Better safe than sorry!


#13

There would certainly be the oxygen displacement issue to contend with, though an open window and a fan are easy solutions there.

Am already considering a CO2 extinguisher for the just in case. (I’d rather not blow any other extinguisher powder all over my work space, should the need arise)

In general, I’m just considering the possibility that I’m tinkering/lasering away in the garage at 2am, when suddenly the dog goes ape in the backyard over something random, and I get distracted…


#14

Another concern is the cost of the inert gas. I’m not sure what a typical ventilation rate is for this sort of laser cutter, but at 150 cfm, a #250 cylinder of nitrogen would last only a few minutes,