Our 1390LC Laser Cutter

  • So, we have 65 hours on the laser since I installed the meter.

    @Vaughn told me he cleaned the lenses in the last couple of days, so I got Jerid to swap out the furnace filter and vacuum out the filter enclosure.

    I tried to fix the x-axis belt alignment issue, to no avail. It looks like the holes were drilled slightly off at the factory and it just took us a while to notice the wear on the belt. In order to compensate, we are going to have to make a mounting plate that gives us control of the pulley angle. Either that or resign ourselves to replacing the belt occasionally, and having spares in stock.

    I confirmed that when you move the Z-axis, the laser dot still drifts down and to the left. Alignment is better than it was at its worst, but is still off. Also the laser, when in focus is not round at all:


    I dropped the bed about an inch and a half between shots. The two hits should have nearly co-witnessed but the beam drifts as it moves down. Also, the close hit beam should have been perfectly circular. Initially I thought maybe the beam was hitting the inside of the lens tube. But this shot makes it clear that it is not hitting near the center of the mirror at all:


    That circle is me rubbing my greasy thumb on the paper and outlining where the hole that goes into the lenses is. Documentation I’m seeing online indicates that we need to hit within 2mm of the center of that circle everywhere on the bed. As it is, we are just clipping the edge of the circle, losing some of our beam, and getting the strongest part of the beam to hit the edge of the lens, which is likely curving it off center.

    About 8 minutes 20 seconds into this video is a pretty good description of how to systematically remove the error from your laser alignment.

    Unless someone comes up with a better suggested procedure, I’m going to try to follow those instructions. @arasbm @Nicholas @MIPS anyone else have suggestions?

    Also, I’ve created a very simple form for logging laser cutter maintenance:

    It just saves info to a spreadsheet in google drive for now. I’d like to capture how many hours before various things need doing so we can start to predict issues. I’ll eventually build it out into `a proper maintenance application with a database backend, but this will do for now. If you do work on the laser, or replace any bits, please use the form to make it easy to track. I’ll try to put it on the desktop on the laser-cutting machine.

  • I did some cutting yesterday afternoon. 3 things:

    1. it’s generally cutting more vertically than when I used it a few weeks ago, eg, my cuts didn’t have a slope to them.
    2. before I started, the bed was not nearly high enough, and the bed was bowed upwards, eg “concave”. It seems the back of the bed was caught on the frame, so I lowered it down and pulled the bed forward, at which point it moved freely, and came up high enough to focus properly.
    3. it looks like the laser is out of alignment when cutting on the forward right corner (towards the control panel) like the laser is diffracted inside the tube and cutting two lines. I noticed this on a few pieces. I’ll see if I can find a sample to get a picture of.

  • I also noticed today, the laser doesn’t look like it’s coming out of the center of the tube at all :(0_1493604223202_20170430_163855.jpg

  • Design Lab

    We should plan a Laser Servicing Party soon! Maybe @arasbm and @pierre and anyone else interested can meet (Hack Night?) and address the alignment.

    I am concerned the laser is hitting the inner housing of the lens enclosure and may be damaging the part!

    One thing to note: when the honey comb is taken out and replaced for cutting on the rails, the honey comb has to be properly aligned on the rails or it can catch under the blue surround! That may even be the cause of the bad being out of alignment with the gantry/laser.

  • I will be there on Thursday for the first aid workshop, after I will inspect the laser and report back.

  • I’m interested in learning as well. Happy to learn the procedures and document maintenance done in the log.

  • Watching this today. Will not attempt the procedure without the assistance of someone who has done it before.

  • @Vaughn The laser has not got nearly the power to damage the aluminum tube. Not by several orders of magnitude. I wish we had that problem, because then we’d be able to cut and engrave metal.

    It’ll mark the anodized coating if it is in focus when it hits it though, which might tell us if we are hitting the edge of the tube after we exit the last lens.

    Beam is about 8mm in diameter before it hits the last mirror so the energy concentration is considerably lower than it is after the lenses. It barely sets paper on fire on a full power pulse. If I could get a decent filter that gave me about 10% IR transmission, we could probably see interesting things by burning paper with the unfocused beam.

  • so @pierre and I did a quick inspection today after the workshop. The laser is out of alignment. It also not hitting in a round circle shape as you would expect. This may be due to damages mirror or lens, or hitting side of one of the mirrors on the way. We need to set a few hours aside and do a full inspection and realignment of the mirrors.

    I do not think it is unsafe to continue to use the laser for now, however you may notice reduce cut quality.

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