Laser – Fire Suppression?

New Home Forum Mostly Printed CNC – MPCNC Advice – MPCNC Laser – Fire Suppression?

This topic contains 4 replies, has 5 voices, and was last updated by  Barry 9 months ago.

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    Okay…I had a major hangup last week when I was using the laser for the first of a four part burn for a sign I am making. About 1 hour in…and the machine froze with the laser on. Okay…I know I am not supposed to ever leave…but I did. I don’t know how lone it was in that position…but there is a nice burnt spot on the “one of a kind” piece of wood I was engraving.

    I am just wondering if someone has installed some sort of fire suppression or a make shift flame/heat detector? I’m not planning on being around the machine for 10+ hours if I am doing a lengthy engrave. My first thought is some of these…


    But I’m a cheapo. I have an extra Arduino Nano laying around and could wire it to an alarm. the thought is I could hook up a thermister (or something else) and have it monitor heat directly above the bed. If it gets above 130°F the alarm is on and I come running with a fire extinguisher. Not really the “automatic fire suppression” I was hoping for…but I have the parts (except the annoying siren but I figure $10-$20 for a smoke detector that I can hack and make work for my situation)

    Has anyone done anything worth sharing?



    Mike Atencio

    Welllll. First off, you should be able to pause the machine when you aren’t able to babysit it. And as you found out, you can’t leave these machines to run unattended. You’re not fixing the problem with an extinguisher/ alarm and eventually you’ll burn something down or at least damage it (as in this case). It’s either babysit the machine or pause it until you can come back and sit.

    That or don’t take on a job you can’t complete. Pretty simple choices. Sorry your wood was damaged. That sucks. Even the big, commercial CNC machines costing mega bucks aren’t ever left unattended. Building alarms are going to give you a false sense of security so please don’t risk everything you own going that route. It’s just not worth it.

    1 user thanked author for this post.

    Dui, ni shuo de dui

    Yeah, you can’t ever know what might go wrong.

    For instance, what if your alarm system fails for some random reason?

    It could be a nice addition, I mean that obviously couldn’t hurt and it might be useful in case you need to go to the toilet or have to leave for a very short period of time, but never get too confident about it.

    For instance, I’ve tested my machine as a 3D printer for already 4-5 months and it has been 100% reliable so far, but I still don’t trust it enough to leave it printing overnight or whenever I’m not in the house. I would even trust it less if it was in milling or laser cut configuration.

    Aside from those considerations, building a fire detector is actually not very easy. You obviously cannot trigger it with smoke, since it will not work fine with laser fumes, I’m pretty sure you can’t use light either, for the same reasons. So that leaves you with heat, but I wonder where you should put the sensor in this case. If you put it on the tool head there is a chance that it won’t get triggered because the fire can catch at some point but then the head will continue to move to another place to continue the cut and might not come back to this point. In which case the fire will have time to grow quite a lot until it finally triggers the thing, if it doesn’t destroy its wiring before or mess up with something else.

    Aside form image recognition with a camera, I can’t think of anything that could work reliably.



    Can use a fridge thermometer as heat sensor and audible alarm:



    We have had fires before, and not the just “hey look smoke” kinds of fires.  Don’t leave it unattended for more than a few minutes.  That’s all it takes.

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