Laser firing randomly when table is bumped!

I’m sharing this more as a PSA than anything…

So I just finished wiring up a new OXlasers 3.5W module on my MPCNC Primo, and even though it started off like a three stooges episode (grbl has poor docs regarding d44… which is ttl spindle pwm by default, anyhow), I have it all wired and configured properly. When I hit spindle on in Bcnc it burns wood, and it turns off when I turn the spindle off… also it is responding properly to M3 pwm changes.

Party time… now to setup the table to burn stuff!

Then it happened… the cnc was powered up while I was in the process of putting away my 3" vise that was previously mounted for aluminum work. I accidentally dropped the vise from about 1" above the table… and the frigging Laser turned on full blast (yeah no eye protection on at the time)!!!

I quickly used my arm to shield my eyes as I scrambled to the screen to turn it off assuming maybe it was a phantom touchscreen press… no response… so I yanked the plug from the laser.

Now with eye protection on, I played with it a few minutes to see what happened. Sure enough, every time I smack the corner of my MPCNC with my palm, the laser blinks. When I tap the laser module directly, wiggle wires, flick the pcb… nothing happens. It’s weird that only tapping the table makes it happen. I figure I may need to check soldering on the laser control board, and double check the pwm duponts on my ramps.

At any rate… with potential sight loss at play, always have eye protection on anytime your laser has 12V available, period.


[edit: FWIW, it ended up being the dupont on my Ramps board… the connector was not pushed all the way in and was barely dangling from the pin.]


Are you the Fonze?

Good call unplugging it before taking off the glasses. These are expensive enough to trust with your eye sight.

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LOL, perfect… now I’m having flashbacks of that Happy Days jukebox! :wink:

Thing is, I did not have glasses on when it happened. So I had to reach for the plug mostly blind (with my elbow covering my eyes except just enough opening to peer to the db9 plug I mounted on the side of the table). I put the glasses on later on when I was troubleshooting it of course.

FWIW, I went ahead and spent over $90 on 2 pairs of OD6 glasses for the wife and I (or whoever is in the room operating with me). The laser came with those cheap red goggles. Even with my OD6 on, you can’t look straight at the dot for more than like 20sec without having some bit of retina burn (like looking at a bright bulb puts a spot in your eyes). I am guessing I may already be half blinded if I trusted those red things.

These are very dangerous toys we’re playing with!

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