[hackerspaces] Laser Cutter Fires?

Morgan Gangwere morgan.gangwere at gmail.com
Thu Apr 30 04:59:59 CEST 2015

At Quelab the rule is that the laser cutter is to be attended to when
cutting. You stick with it.

I've had a few small fires from wood, but nothing dangerous. We only allow
materials that have been cleared, and that clearance includes a test run
with a couple of people just to check if it lets off anything noxious.

As for remedies, we have a fire blanket next to the door and next to the
On Apr 29, 2015 18:43, "matt" <matt at nycresistor.com> wrote:

> Foam Core torched our old epilog at resistor.
> Biggest fire we had.   Did significant damage.
> And frankly we're occasionally ... adventurous with our burninantion.
> -matt
> On Wed, Apr 29, 2015 at 3:51 PM, Nathaniel Bezanson <myself at telcodata.us>
> wrote:
>> Thinkhaus had a small fire back in 2011:
>> http://www.thinkhaus.org/2011/04/03/lazzoring-is-serious-business/ and
>> their post about it has become part of i3Detroit's standard laser cutter
>> training. Thanks, Thinkhaus!
>> At i3, we've had a few small fires in the chamber, though not by the
>> apparently-common tray fires described by others in this thread. For us
>> it's the material being cut, remaining aflame after the head moves away. I
>> think corrugated cardboard is the usual culprit, since it has channels that
>> can sustain "peaceful" combustion, even as the air-nozzle blasts down from
>> above. (There's a project idea floating around, to use the oxygen-poor
>> exhaust of a medical O2 concentrator, or just a plain old tank of argon, to
>> supply the air assist blower with inert gas during the entire cut. I'd be
>> super curious if anyone else has tried this and how it went! It should
>> reduce edge char too, no?)
>> Most folks just pause the job and Big Bad Wolf the flames, but the
>> extinguisher has come into play at least once.
>> I don't know how others' cutters are constructed, but on our big
>> machines, the platform (tray?) is several inches below the cutting plane
>> (there's the honeycomb, and then the slats, and then a gap caused by the
>> slat bracing), and while the beam is still focused enough down there to
>> melt through adhesive tape, I'm not aware of anything ever having caught
>> fire in the tray. That's a good point worth making, though; we should give
>> it a look after shutting down the exhaust, in case anything down there is
>> smoldering.
>> In addition to linking to the above Thinkhaus page from our tool-info
>> page, I make a point to discuss the incident during training. (I don't know
>> if other trainers do, but operators are supposed to be trained twice by
>> separate trainers, so I think most have gotten The Talk.) We have a strict
>> "do not walk away" policy, and have recently mounted a phone/intercom near
>> the operator's position to help with this. Sometimes when I walk past, I
>> make a point to offer to grab a soda for anyone babysitting an active job,
>> even though I know they could easily pause the job and get their own, since
>> I want to emphasize gratitude for their vigilance.
>> We have a checklist for operation, which includes "lift the fire
>> extinguisher from its spot and set it back down" as the last step before
>> pushing Start, with the intent of both confirming that it's always there,
>> and building the muscle memory of how to unhook it. That's a 5-pound
>> nitrogen unit, which is what the service place offered as a replacement
>> when our beloved halon unit went out of date. (That's a tradeoff.
>> Nitrogen's environmentally harmless, but pound-for-pound, inert gas isn't
>> as effective as halocarbons at actually extinguishing fires.)
>> In the future if we ever get a tool-auth system going, in addition to
>> badging into the laser to prove that you're on the operators list, I'd like
>> to rig a switch so it confirms that the extinguisher-mount changes state
>> before enabling the machine. For the time being it's all manual.
>> Also sitting nearby is a 20-pound CO2, which every laser operator is
>> encouraged to practice with before getting certified. We blast each other
>> with it and generally treat it as nonthreatening, in hopes of building
>> familiarity and reducing hesitation in the event of an actual fire. It's
>> cheap to refill, and since it's not the "official" extinguisher for the
>> area (that would be the nitrogen by your knee), I'm not worried about
>> running it empty playing with it. That's happened once already, and I think
>> the practice and familiarization was well worth the trivial refill cost. I
>> plan to swap it for a 10-pound next time it's due; the 20 is clunky to
>> handle.
>> I've had a LOT of folks say it was the first time they ever actually
>> pulled the pin on a fire extinguisher, much less discharged one. I think
>> this is important -- we practice CPR on dummies, we practice fire drills by
>> walking outside, even the AED has practice pads. Why isn't it more common
>> to rehearse with actual extinguishers? They're cheap and fun!
>> There's another 5-lb clean-agent (halon or nitrogen, I forget) in the
>> electronics lab, and the rest of the space has big dry-chemical
>> extinguishers everywhere. Most are mounted right near the supply-stations
>> (paper towels, tape, pens, markers) in each zone, to capitalize on the
>> habituation of turning toward those during other instant needs, such as
>> spills.
>> -Nate B-
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