Catching Fire on the new laser

Laser
#1

Today a fellow member and came in early to laser cut some Radio Controlled plans from Dollar Tree $1 foam. We have previously cut many sheets of foam on the lasers. One of them was un-serviceable and another was occupied so we had to use the NEW laser. Does it have a name? (The one in the middle).

We used some of the same settings we used previously and the foam caught fire. We extinguished the fire and reset the setting to much lower settings. The cut still caught fire.
We then changed the settings to very low settings (15% at 250mm) and the cuts were insufficient to cut entirely through the foam. I presume we could lower the settings further and cut multiple times, but this extends the amount of time on the laser and makes each cut more time consuming.

Any suggestions?

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#2

With effectively zero experience, I offer my observations/perceptions of what others have suggested:
Is the air assist on? Having it off or improperly aimed might cause flame up. I have the impression, anyway. Maybe someone with actual experience can weigh in, too…

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#3

The overriding rule in Laser is: If you don’t know what’s in the to-be-cut materials down to the MSDS level, you likely shouldn’t be lasering it.

What exactly is in this foam? What type of foam is it?

Do you believe the Laser is damaged as a result of the fire? Have the optics been sooted?

Is anyone who’s been cleared to check the Lasers onsite to inspect the laser in question? Paging @Team_Laser

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#4

The normal paper skinned foam core board has never been restricted that I am aware of.

But air assist isn’t just about protecting the lenses, it is also about blowing away and diluting combustible fumes before they reach flamible concentrations. This really sounds like air assist not turned on, or disconnected somewhere.

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#5

Since you were using “old machine” settings on the “new hotness” it was likely too much power or too slow.

You should retest on the new machine with faster and lower powered settings and creep them up until they just make it through.

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#6

What folks have said is good. Move fast, make sure the air assist is blowing, don’t use more power than you need, make sure the focus is correct, and settings can vary over time.

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#7

When my son was doing some raster work on the big laser we found that a power level of 5% did not consistently fire the laser. We had to get above 8% but then needed to double the speed. Even then we had deep markings.

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#8

Foam core is allowed.

I suspect a problem with the Air Assist. The compressor was offline yesterday for repair (we took the lasers offline). I would check to make sure it is running and that the system has compressed air for the air assist.

@Lampy that’s weird, and a problem. Normally 3% power will fire the laser.

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#9

Cathy and I had the same issue Tuesday. 1% to 7% would not fire the laser. Previously the floor was 5%.

#10

Do we want fire or not? :stuck_out_tongue:

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#11

I took a class in cutting this foam making RC airplanes on the laser. It is definitely on the approved list.

No. The fires were very tiny and quickly extinguished with the CO2.

There was no one onsite at the time, but that is why I posted on talk as soon as possible.

I truly believe that no damage was done. I also believe that as @kbraby said it was a problem with air assist. It is possible that it wasn’t turned on. I don’t recall hearing the air being on. I apologize for not following the checklist provided. My friend had just cut several sheets without problem so I assumed he was using the air assist.

Lesson learned.

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#12

Scott, here’s the info on the Wiki for the foam and RC planes. https://dallasmakerspace.org/wiki/Flitetest_Planes

#13

I do agree with Pearce’s Advice regarding the new laser being stronger using the old settings.

Sounds like you did all of the right things. Carry-on and happy lasering!

#14

Can confirm. I tried to do 5% on some fabrics a few weeks ago and it wasn’t firing. Had to bump up speed and percent to adjust.

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#15

To check air assist, start a test cut and pause it. The air assist should still be engaged. Open the lid and check for the blast of air under the nozzle.

Then cancel the test cut.

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#16

“Do a test” is my standard practice for pretty much any marking/cutting tool that’s new to me or been out of my sight since the last time I used it.

Laser cutter, jointer, planer, table saw, band saw, router bit, skiving knife, utility knife blade, bottle of dye, calligraphy pen, you name it. First touch/cut is on something I can afford to toss.

#17

FWIW - Was in yesterday morning and got a flare-up. I immediately stopped the cut. I found that the AIR ASSIST was OFF!! Who is turning it off and if they do, why are they not turning it back on when they finish??

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#18

I still strongly feel like the hazard of allowing users to adjust/turn off the air assist outweighs the benefits. @Team_Laser can we just remove the shut off valve and pipe past it?

#19

I agree regarding the big laser. We could leave one of the smaller ones with the valve for people who are crazy enough to want it off.

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#20

I know, “how hard can it be” is the sign of someone who is too dumb to understand…

Would it be possible to add an electronic solenoid valve to the air assist line, and have it default to “air assist YES” and reset after every job? With … a button to toggle it off before a job? Ok the more I think about it the more complicated it gets.