So, this happened ('small' fire)

millerized · March 10, 2024, 2:26am

3 month old OMTech 1060 24x40 100W CO2, had issued with the autofocus nearly since new. Several back and forth with OMTech, nothing permanently fixed. Disconnected the autofocus, turned off the z axis stuff if the software and did manual focus from then on.

Had a need to play with the autofocus a few days ago. Turned it on, clicked the autofocus button and sparky and smoky show up inside the drag chain and the power goes off. Closer inspection shows about 6" worth of melted wiring and air line inside the drag chain. Shoot off an email to OMTech telling them about the problem.

OK, great, but I need this running tonight, so I replace the wires in their entirety, from autofocus sensor back to the controller. One for one swap using some spec grade stuff I’ve been using on my cnc builds, made for drag chain use, flexible, UV/ozone resistant industrial stuff. Everything is back together that even. A few test runs, temperature checks on the wires and we’re good to go.

Drop in the ‘needed it done today’ job, hit the button and woke to the smoke alarm telling me my shop was on fire. Yeah…this is going to be pretty. Figured a little bit of smoke, nothing big.

Until I got to the door of the shop and could see the yellow flames dancing out of the top of the engraver. Open the door, smoke to about 3’ off the ground, alarm going, exhaust fan going, and fire about 2’ out of the unit. Fire extinguisher was right behind me, so I fill the engraver with that fun to clean out white powder. Yeah…this is gonna suck to clean since the fans blew it all over the shop. Just stood there, wondering what happened, staring at the machine I just put back together and had running just fine. Guess I’ll clean it up and see what happened. Waited until it was cool, and went back into the house.

Inbox has a "“We’ll send replacement parts right out” from OMTech, to which I reply “Yeah, don’t worry about it, the engraver caught fire and is pretty much out of the picture for the future”. A few back and forth, but since I put in the new wires, they won’t cover anything. Pretty much what would have happened if I put in the wires THEY sent me, so there is no warranty to worry about. Know that once you put a sticker on the front, or change the air pump and put in a solenoid or swap out the anemic exhaust fan (like all of us probably have), you have just voided the warranty, and OMTech won’t touch it. Understand that up front before you even ask. If you turned your back on the machine, left the room, or fell asleep…cardinal rule broken, and you’re SOL with regards to warrant, so don’t even ask. You can lie. I could have lied. I didn’t, and “I” get to fix my own machine. No good deed and all that.

Fortunately, everything in that machine is available online, either AMZ or EBY or a hundred other sources. Linear bearings, 15mm HD belt, proximity sensors, wire, motors, pumps, hoses…all cheap and assembled by sub-NASCAR IQ folks. This happened on a Saturday morning, and it was back up and running the following Friday. Unfortunately, it’s about $700 that I didn’t have to spend on fixing a 3mo old machine. But it is what it is, and it was what it was. If you come in to the need to fix things, broken, worn out, small toasty-q happens, the parts you’ll find are much better than what came with it. Hell, the belt is metal reinforced this go-round.

After action: Fire was caused by the final ‘cut out’ stage of a long engraving process. The material (laser ready acrylic sheets, specially designed for engraving) had a lot of smoke build up under the honeycomb bed. Every now and then you’d see the fire on wood…this was no different, other than the concentration. The 310cfm bilge fan could not keep up with the 15psi air supply pushing the smoke down, and the smoke flashed over. The constant cutting (126 circles were being cut, aka 63ea 3" rings) made too much smoke, she reached the wrong concentration and went poof. And kept poofing until things didn’t unpoof. The big metal scraps pan on the bed of the engraver was clean before we started, the honeycomb was clean, the knife supports were clean. Just the gas ignited and stayed lit.

Prevention: Higher velocity exhaust fan, onboard fire sensor and extinguishers (made for under car hoods, whodathunkit) and a pair of thermal fuses to shut the machine down if it gets over 130 under the hood. Also, put a 4" pancake fan under the bed, off the side facing the center to help disperse the fumes and blow them towards the bigger fan in the back. And, lastly, purchased a replacement, different type of extinguisher for the shop.

#1 Do NOT leave your machine unattended.
#2 Do NOT modify your machine in any way if you want to maintain your warranty.
#3 Do NOT forget to have a networked smoke and fire detector so you can get notification wherever you stay if you’re not watching your machine. (read #1 again) One in the shop, one in the attached garage and one inside that wall which is the living room…all tied together
#4 Do NOT skimp on your purchase of a fire extinguisher.
#5 Please don’t follow my example of ‘I need it now, I’ll fix it’ unless you don’t care about the under warranty damage you fixed on your own and own a great fire extinguisher and smoke detectors.
Your mileage might vary, remove clothes before ironing, objects in mirrors and all that stuff.
burnt wires in the chain tray

So much happiness in one photo

one week after the fire

LSS · March 10, 2024, 7:32am

Hi.

Thanks for sharing.
I have a hunch that these things are more common than we think, people just don’t report them.

Goes to show why it’s never a good thing to leave any machinery unattended while on the job, and how the ample airflow below the workpiece is also crucial when cutting with laser or plasma.
Or oxy-acetylene for that matter.

As for the fire extinguisher, providing the local legistlation allows the use of Co2, that’s by far the better choice at least as the mess is concerned.
As well as Halons that are probably banned almost everywhere in domestic use, Co2 does have its fair share of risks which has to be understood before using such a fire extinguisher or fire suppression system indoors.
Even more so if the system is automatic.

Even before I noticed the hobby grade automatic ~12g Co2 cartiridge extinguishers are available for our hobby lasers, I toyed with an idea to convert a larger ~425g soda-Co2 cartiridge into an automatic fire suppression system.

The engine compartment Co2 and Halon fire suppression systems used in the high performance cars and boats You mentioned could also be an alternative.
As would a Hi-Fog (-style) system as well.
But the price skyrockets very quickly.

Regards,
Sam

bernd.dk · March 10, 2024, 7:53am

Thanks for sharing this. There have been many threads regarding the fire hazard of our machines and your report is a sad confirmation of the basic attitude towards it. Especially your conclusion that the “right” gas-air mixture that leads to smaller explosions in the honnycomb matches my experience. Acrylic has this property widely, but I have also seen it with normal wood.
It is a pity that OMTECH’s guarantee does not cover your accident, for 2 reasons. Firstly, you could have been good without the extra financial burden and the production loss, secondly, it indirectly encourages you to be dishonest otherwise you become “cheated”. - It is wrong.

On the posetv side, it is good that your workshop did not also burn down and no one was injured.

millerized · March 10, 2024, 6:32pm

https://www.amazon.com/Ougist-Automatic-Extinguisher-Effectively-Extinguishes/dp/B0BY4PCCTN is the extinguisher modules. One placed toward the top of the window on each side, but still within the cutting area. Thought about everything from Halotron through CO2, but the trip sensor is the hard part, as well as expensive. I have an assorted box of fusible links (soldered metal), that and a spring loaded something…and the bottle gets emptied kinda deal. I’ll keep playing, but the laser doesn’t get run without either the wife or I in the shop. Even as ‘protected’ as it is now, I can’t play that game again.
My lesson is learned, and it could have been a lot more expensive than it was. Could have been a lot LESS expensive, but my lessons are rarely cheap.

LSS · March 11, 2024, 4:58am

Hi.

True, trip sensors are always the hardest part on systems like that, but…

Those work very reliably, as do the plunger/bulb types used on smaller air duct fire dampers.
Both are also affordable and come in a variety of breaking temperature and exposure ratings.

Another one that works well are one-way acting sprinkler heads, even though the exploding bulb may cause some small inconvenience.
Not nearly as much a fire would though.

Very wise choice.
I always shudder when someone asks -or demands- that LB should be able to control lasers remotely over a great distance.
Granted, if used wisely that’d offer some undeniable advantages, but one doesn’t have to be very imaginative to come up several ways to things go very bad, very very fast if used sloppily or without thinking what may happen.

The good ones rarely are .

But, since You shared Your lesson (and I thank You again for that), also others can benefit from it.
From personal experience I do know that’s a rather small condolence, but that’s the method I’ve used with my similar lessons.

Regards,
Sam

Rob_H · March 11, 2024, 6:34am

If you are looking for the latest High tech in home/shop firefighting you may want to have a look at this:

&

Okay, maybe it’s not really that high tech but it works on most fires you might have in your laser.
One word of caution though, if you have a cat keep your pail of sand covered unless you want him to leave you a little gift.

millerized · March 11, 2024, 1:58pm

LOL. I DO have 2 shop cats now. 2 ‘end of life’ cats that need the protection of a roof over their heads and ‘secure’ environment from other cats. Not that the fire hurt them, but I’m sure that’s the last thing on their minds while basking on the 80F radiant heated floor.

But now either the wife or I being in the shop the entire time it’s running, and with the internal protection of the 2 ‘fire activated’ extinguishers, I have a feeling (aka hope) I’ll sell the machine in 10yrs with everything still intact. Once is enough. The removal of the honeycomb and all knife edge table, the air movement under the bed…I’m hoping everything is unnecessary going forward. I’m even tempted to tie the thermal fuse into the building alarm system, but that would be temptation to leave the building. Yeah, no.

I can still ‘see’ myself as I walked into the shop and just stood there. I knew the fire was small enough that it wasn’t going to ‘go’ anywhere, but the incredulous look on my face as I stood there saying ‘dammit…I just fixed this thing’. I’m still laughing at my reaction. I guess I’ve had enough ‘events’ in my life even a fire doesn’t phase me any longer. “Gee…is that 'friendly fire, or is the enemy shooting at me again?” kinda deal.

millerized · March 11, 2024, 2:03pm

mistakesdemotivator

LSS · March 11, 2024, 3:07pm

Hi.

Yep, That’s the feeling .

Regards,
Sam