This is why we never leave the laser cutter unattended…

Burnt stock

So last week we had a little bit of a fire in the small cutter. What you see above is the bottom side of some stock that I was cutting that ignited. Luckily I was watching it so it only was burning for a few seconds before it was caught and the fire was handled. The fire was entirely under the material being cut so it went undetected for a little bit (in fact the top side of the above sheet is warped but not burnt in the slightest compared to the bottom).

Damaged Vector Grid

The vector grid delaminated a bit so it's toast and the connector for the rotary attachment got a little charred. The Delrin slides at the back of the machine that the downdraft ports the Z-axis tray ride on got more than a little melty as well (pic below). After closer inspection it looks like the dusk accumulated in the back of the machine ignited as well.

Melty Parts

Fortunately nothing above the stuff being cut was effected and the optics were just fine. The flames were easily controlled with the squirt bottle I keep handy around the cutters and we've got a proper CO2 extinguisher if things get really bad. I didn't have a lot of material in the catch tray to act as fuel, but enough that a flare up turned into a little fire. We've got an extra vector grid on hand so we were back up and cutting withing 2 hours after checking everything out. Thankfully with a quick call to Epilog and I can get replacements for everything damaged as well.

It looks like either the different masking material of the frosted acrylic I was cutting or insufficient air flow at the active cooling tube might be the culprit. The compressor was reading 30 psi, but much less than that was getting to the actual head. I tightened up a leaky fitting after the dryer that helped but I'll be giving that entire system the once over this week. Either way, I'm glad that even after 4 years of running the cutters I still walk over and check them every couple of minutes when it's operating and always make sure someone's watching them when I can't because this flare up could have turned into a full on fire rather quickly.

 

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2 Responses to “This is why we never leave the laser cutter unattended…”

  1. Djuradj Vukovic says:

    Wow that looks like it could have been bad, if you weren’t nearby

  2. Oren Beck says:

    Smoke Operated Relay and Nitrogen Inerting the box when possible? Do note that an N2 flood would easily stop “most’ non-exotic material fires with lower risks than CO2.

    CO2 risks are thermal shock and ESD more than any other factors. N2 does have “some” ESD percentage but it’s negligible by comparison that I’ve experienced.

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