PSA: I am guilty of reading about not leaving the laser unattended, but doing it anyway. An employee was cutting some acrylic and we are not in the habit of watching it when running.
There were 2 other employees working within 15 feet of the laser, but the fire was able to burn for 6 minutes before being noticed and put out with a fire extinguisher.
The employees were running other production machines and did not see or smell the fire as is was contained in the enclosed machine. An employee used an ABC extinguisher. We were lucky the fire didn't do worse damage to the machine or building.
Best guess as to the cause...we were using some orange plastic supports under the acrylic to avoid nicks on the edge of the cuts. We think the laser ignited the plastic under the acrylic and started the fire.
Lessons learned. don't leave the machine unattended when cutting, don't use flammable items as supports, also looking into some type of auto fire suppression system.
HERE IS THE FULL VIDEO:
Luckily Thunder's tempered glass viewing windows kept the fire contained. If the machine had acrylic viewing windows, the outcome could have been much worse.
On the note about automatic fire suppression, have a look at this:
Here is what the aftermath looked like:
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