Laser cutter



  • @pierre
    Hey. About half way through a cut today the laser stopped firing on the laser cutter. I’m not sure what’s up. I know the mA were hovering around 12 -14 for the cut.No funny noises or anything like that that I could hear. I tried to pulse it once and got nothing. I didn’t want to mess with anything else but it would seem to me that the laser cutter is down.


  • Classroom

    Thanks for reporting @chrisyewchyn.

    Did you happen to notice if the water was flowing for the chiller unit? There is an interlock that can stop the laser from firing if the water isn’t moving. If the laser stopped mid cut this could be the culprit.

    I’m hoping the 12-14 mA you noted were while the laser was still cutting and not after it stopped—as that would indicate a much more serious problem—can you please clarify?



  • Chiller sounded fine but I didn’t notice the flow. The mA dropped to 0 after it stooped firing.
    Hope this helps.


  • Classroom

    @chrisyewchyn said:

    Chiller sounded fine but I didn’t notice the flow. The mA dropped to 0 after it stooped firing.
    Hope this helps.

    That helps for sure! It could be a good sign, and gives some info to start troubleshooting.

    I think, that the drop in power most likely indicates that the power to the laser was cut off by an interlock. This could either be chiller flow sensor, or lid open. @pierre was talking about installing another one or two I think, but I’m not sure if there are any others besides these.

    Did you put any signage on the machine? I’m guessing some folks will be around shortly for Maker Monday, and hopefully someone can have a look and at least put up signage if there isn’t some already. I won’t make it in tonight, but I will tag the usual culprits that I expect may be (thanks for all your hard work folks). @KillwithKindness, @pierre, @megan-fenkhuber, @Vaughn



  • I wrote on a piece of tape that it was down and sealed the door with it.


  • Classroom

    @chrisyewchyn, awesome!

    Thanks for doing all the right things in this case.



  • The reservoir on the chiller was empty. The pump was not moving liquid, and the water outlet line was lying on the floor. Oddly, there was no puddle of liquid on the floor (Several gallons of water and glycol should have been on the floor…) There was a thick, fluorescent green, jelly-like residue in the reservoir, like a lot of glycol had evaporated. @Krankin, @megan-fenkhuber and I refilled the reservoir and the pump fired up again. The tube is still not firing. I think the liquid is in the wrong places. The outer jacket is full of liquid, and I think it needs to be trapped between the second and inner layer of glass. I’m going to talk to the manufacturer to see if I’m making the right assumptions. It is possible that the flow-switch is jammed from the thickened glycol, at which point the laser would have briefly fired with no water flowing through the tube.


  • Classroom

    @pierre thanks for the update!

    Yikes, this looks a little more serious than I had hoped. Hopefully the dry firing time was limited, and we can get the goop out.

    If the laser manufacturer recommends an organic solvent that could melt the goop without hurting the tube, then I can try to get my hands on some from the chem dept if it isn’t readily available.

    I would probably want to start trying with methanol if the supplier says it should be safe. It is easily available, fairly inexpensive, minimally hazardous, and has less severe effects on most rubbers and plastics than other organic solvents.



  • I would just crawl into the back of the laser cabinet, unplug the line from the flow switch, and see if the pump can fill a bucket. If it can then I would try reconnecting the line to the flow switch again. Water is the best universal solvent



  • Water is flowing through the return line fine. I left the pump plugged into the wall over night to see if it unsiezes anything.



  • I ran the pump and water is flowing. I made a float level indicator from a dowel and a block of wood and topped up the tank. I also fixed the lid to fit better. Could not test fire, key too well hidden. 0_1511929160344_20171128_200129.jpg


  • Member

    @Grant-Fraser said:

    I ran the pump and water is flowing. I made a float level indicator from a dowel and a block of wood and topped up the tank. I also fixed the lid to fit better. Could not test fire, key too well hidden. 0_1511929160344_20171128_200129.jpg

    key is hidden in the yellow tool box in the lid.



  • Thanks, got it. Bad news. We’ve broken another laser. The outer jacket is filled with water. It is trying to fire the laser through 2 inches of water. 0_1511931992753_15119319720131137712711.jpg



  • Good-ish news. It appears it’s only the water jacket that’s broken. It’s worth it to try cutting through the outer layer and patching the inner layer with rubber hose or JB Weld. If anybody has a friend in the neon sign business we could use some help. I don’t expect a glass repair as the sign shop wouldn’t have the exact glass to work with. I am hoping they can help cut the outer tube without breaking it. 0_1511935511318_20171128_215906.jpg



  • Hmmm. Maybe don’t shoot any more test-pulses with the electrode submerged… Can’t be good for the power supply. I have no idea if the warranty will cover that leak, but I’ll see what they say.


  • Design Lab

    A laser-less Christmas then?? Say it ain’t so!



  • Here is an interesting FAQ page. It says that the laser tube should be kept between 25 and 30 degrees celcius and that in colder climates we should drain the laser between uses. Not really practical. I will suggest that we can make a much fancier chiller unit. One that warms the water to 25 degrees before use and keeps it under 30 degrees. And make it interlock with the laser.

    http://efrlaser.com/profile/faq/200473/0/


  • Classroom

    @Grant-Fraser, I have often wondered if our chiller unit may be too efficient. This seems like a valid issue. I had assumed that the tubes were likely borosilicate glass and should stand up to the temperature changes better without cracking.

    I’m wondering if a less expensive laser tube might be associated with less expensive glass thereby increasing the failure rate, especially with overkill cooling. I’m not saying we have that, just that if we did, it would kill cheap glass faster than HQ borosilicate glass.

    I have no idea what any of the tubes are actually made of, but maybe it is something worth examining when we are comparing specs.


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