[hackerspaces] Laser Cutter Fires?

matt matt at nycresistor.com
Thu Apr 30 17:06:48 CEST 2015

coherent scimitar?

On Thu, Apr 30, 2015 at 8:08 AM, James Arlen <myrcurial at thinkhaus.org>

> It is worth noting that I watched the acrylic burst into flame.
> Saying "you have to stay with it while it's running" is just not enough --
> and you WILL run right past the closest fire extinguisher.
> The most important thing to remember is that a laser cutter is an
> industrial tool and you need to treat it with respect.
> Also, seriously, we are talking about how we all regularly use a photon
> sword (the other term is TM Lucasfilm/Disney) and that's pretty damn cool.
> --
> James Arlen
> On Apr 29, 2015, at 22:59, Morgan Gangwere <morgan.gangwere at gmail.com>
> wrote:
> 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
> cutter
> 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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