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Laser cutters

RS_JimRS_Jim Posts: 1,766
edited 2013-02-28 09:07 in General Discussion
Hi,
Two questions, is there anyone in the Phoenix area that has one and is it possible to cut clear PVC with one if it has paper backing.
Jim

Comments

  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2013-02-05 09:16
    You must never cut PVC with a laser cutter. Doing so releases chlorine gas, which is not only poisonous but hightly corrosive to the laser cutter's electronics.

    -Phil
  • RS_JimRS_Jim Posts: 1,766
    edited 2013-02-05 09:45
    Thanks Phil, Iguess I should have realized that problem.
    Jim
  • LeonLeon Posts: 7,620
    edited 2013-02-05 12:12
    Perspex/Plexiglass seems to be OK.
  • Brian CarpenterBrian Carpenter Posts: 728
    edited 2013-02-06 19:49
    i have a CNC and am in the phoenix area. i can assist in the cutting of your PVC
  • GordonMcCombGordonMcComb Posts: 3,366
    edited 2013-02-07 08:43
    You really want either rotary cutting (like Brian's CNC) or waterjet. This leaves a nice clean edge.

    What PVC are you using that's clear and has a paper film on it? That sounds more like acrylic. Either cast or extruded acrylic is infinitely cuttable on a laser, and leaves a good edge with no scorch marks.

    -- Gordon
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2013-02-07 10:02
    If in doubt, you can always use Rich's (W9GFO) test for chlorine content:
    1. Grab a chunk of pure copper -- not a penny but, for example, #10 solid wire with a small loop formed in one end.
    2. With pliers or Vise Grips, heat the copper in the flame of a propane torch.
    3. Touch the heated copper to the suspect material to melt it and pick up a glob.
    4. Return the copper and melted plastic to the flame.
    5. If the molten plastic on the copper burns with a green flame, it contains chlorine and should not be laser cut.

    -Phil
  • Mark_TMark_T Posts: 1,981
    edited 2013-02-07 15:31
    Phil Pilgrim (PhiPi) wrote: »
    If in doubt, you can always use Rich's (W9GFO) test for chlorine content:
    1. Grab a chunk of pure copper -- not a penny but, for example, #10 solid wire with a small loop formed in one end.
    2. With pliers or Vise Grips, heat the copper in the flame of a propane torch.
    3. Touch the heated copper to the suspect material to melt it and pick up a glob.
    4. Return the copper and melted plastic to the flame.
    5. If the molten plastic on the copper burns with a green flame, it contains chlorine and should not be laser cut.

    -Phil
    All copper compounds burn with a green flame - but pure copper needs to be very hot to start giving off much green flame
    (the oxides are not volatile), chlorine compounds make copper chloride which sublimes at lower temperature I think,
    and colours the flame much more strongly. To avoid being fooled check the flame colour with and without the plastic sample - its
    very different. There could also be yellow in the flame due to tiny amounts of sodium impurities, there usually is,
    ignore this.

    And don't breathe in the vapours!
  • W9GFOW9GFO Posts: 4,010
    edited 2013-02-07 15:41
    When you heat the copper with the torch you will see what the flame looks like without any chloride-containing plastic residue on it.

    Best to test on something that you know will get a positive result such as a piece of PVC pipe and also test on something that you know will get a negative result such as acrylic or ABS. You don't need much material to be picked up on the hot copper, just a half-second light touch is enough.
  • GordonMcCombGordonMcComb Posts: 3,366
    edited 2013-02-07 16:01
    Seems to me the acrid smell and the itching sinus membranes would be all you need to determine if the plastic is giving off chlorine, and the color is just for pretty looks!

    To be specific, the chlorine gas is poisonous to us, but the corrosive element is hydrogen chloride, which when mixed with the moisture in the air produces hydrochloric acid. That is the stuff that eats your precious little laser cutter parts.
  • RS_JimRS_Jim Posts: 1,766
    edited 2013-02-28 09:07
    Ok, I know the plastic is pvc as the label states this fact. Thanks for the testing techniques will save them in case I need for future reference.
    Brian I will contact via PM.
    Jim
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