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Thread: Bad tube?

  1. #1

    Bad tube?

    Would it be safe to say this is a bad tube? This is marked on the mirror directly by the tube. The tube lens is clean.
    PXL_20201002_142929901_2.jpg
    Rabbit QX80-1290
    TTP Stingray
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    CorelDraw 2018

  2. #2
    Steve

    I would check all the mirrors and the lens then do some other tests before blaming it on the tube. It could be that, but a call to your supplier might point you in another directiion.
    Mike Null

    St. Louis Laser, Inc.

    Trotec Speedy 300, 80 watt
    Gravograph IS400
    Woodworking shop CLTT and Laser Sublimation
    Dye Sublimation
    CorelDraw X5, X7

  3. #3
    Need info-
    tube power
    % of power applied for that test
    length of test--

    Remember, the incident beam from the tube is un-focused. I'd be more interested in what the focused beam is doing...
    ========================================
    ELEVEN - rotary cutter tool machines
    FOUR - CO2 lasers
    THREE- make that FOUR now - fiber lasers
    ONE - vinyl cutter
    CASmate, Corel, Gravostyle


  4. #4
    Join Date
    Mar 2011
    Location
    Olalla, WA
    Posts
    1,532
    If you want to see the beam profile take a piece of clear acrylic, the thicker the better, and place it in the beam path far enough away from the output of the tube to avoid getting the window dirty but close enough that the beam is not passing through any mirrors. Make sure it won't move. Burn at high power until a pattern develops in the acrylic.

    If the beam profile is good you will get a result like in these pictures.

    TEM00_1.jpg TEM00_2.jpg TEM00_3.jpg

    If the beam is not good you may get something like this;

    Bad profile.jpg
    Shenhui 1440x850, 130 Watt Reci Z6
    Gerber Sabre 408

  5. #5
    Thanks for the replies. I don't think it was a bad tube at all. I have had to do almost no re-aligning since I've had my machine, so I find it hard to recognize different things when it comes to those burn marks. I have been having some strange problems lately, and I am trying to figure out what is the culprit. The picture below shows some of the issues I am having. The circled areas show that whenever the laser is making a pass over both tags, the beam seems to stretch. At the left end of the left tag, the V and I are pretty close to what they should be, but if you look at the T in "HOST", you can see that it is stretched just on the bottom. Not to mention, the edges everywhere are quite a bit more rough than usual. On the right tag, the stretching happens in the opposite direction. Those are the engraving issues. Then, if you look at the top right corner of the left tag, the laser didn't finish off where it started.

    The laser is aligned, and all of the lenses and mirrors are cleaned. The belt tension is good and nothing else seems to be loose. I was using a vector file for cutting, so all the edges should be clean.
    PXL_20201005_201627844_3.jpg
    Rabbit QX80-1290
    TTP Stingray
    LogoJET UV2400

    CorelDraw 2018

  6. #6
    That looks mechanical. Could be simply the lens holder/tube is loose, and is shifting slightly -left to right when the head stops and changes direction- and may stay that way for several sweeps, then shifts back.. Or the lens itself may be loose IN the holder... Or, could be an almost-tight set screw on the X axis stepper pulley... or where the belt connects to the lens assembly, could be one of the mounting or adjustment screws is a bit loose...
    ========================================
    ELEVEN - rotary cutter tool machines
    FOUR - CO2 lasers
    THREE- make that FOUR now - fiber lasers
    ONE - vinyl cutter
    CASmate, Corel, Gravostyle


  7. #7
    I have checked all of those things. I have re-aligned my machine, tightened the belts, tightened all the set screws, and checked the lens holder. If it was something loose, I would almost expect the engraving/cutting results to look slightly different every time, but I am consistently getting the stretching in the same places, and the cutting is consistently coming short when I am cutting anything more than one piece at a time.
    Rabbit QX80-1290
    TTP Stingray
    LogoJET UV2400

    CorelDraw 2018

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