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Thread: Troubles with fiber laser engraving copper

  1. #1

    Troubles with fiber laser engraving copper

    Hi everyone,
    I have been trying to deeply engrave on copper with my 30w fiber laser. What happens is it seems to only go so deep and it wonít go any deeper. I saw an Ezcad video that showed you should have 3 hatches and the middle one should be parameters that will get rid of the slag build up. Unfortunately the video was kind of tough to understand. Should I have some kind of a clean up hatch in the middle? Is that the reason it just wonít engrave any deeper? I ran a small graphic almost a half hour and it hardly engraved at all. Does anyone have any suggestions as to the parameters needed to deeply engrave copper using the Ezcad software with a 30w fiber laser?
    Thanks, Marianne

  2. #2
    When I want to go deep I find that after a few passes the noise the laser makes eating into the metal gets quieter which indicates not much is happening, so I wind the focusing wheel down a bit until the noise builds up again.
    Shenhui SG350 fitted with a 60w tube.
    JQLaser 9060 with 90w tube.
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  3. #3
    Fiber lasers don't engrave pure copper very well, if at all. I have a thin 8" x 32" pure copper sheet, my fiber won't do a thing to it, just reflects off (which is dangerous!). But my laser will mark copper pipe, which likely has something else in it, like tin, zinc, etc...


  4. #4
    Thanks, Iíll try to refocus and see if that helps!

  5. #5
    Thanks Kev, yes Iím really struggling with both copper and brass. I might just end up not using copper as much!

  6. #6
    What lens are you using? That will play a major role in the results you get. The smaller the focal length the smaller the beam will be with higher power density. I use a 100x100 (f160) lens when I'm working with copper and certain types of brass. I try and arrange the artwork towards the back of my week area to limit reflections and scatter. Most of the time my 200x200 lens sits on the machine but I do change it when needed. Sort of like having a favorite camera lens but you still need the right lens for the job.

    I've been looking at the 70x70 (f100) lens for awhile and saw Kev recently bought one. I'm ordering one this week for tougher materials and a little time savings.
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  7. #7
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    I had posted a couple months ago about having trouble with electrical Copper cubes. I placed a few in the freezer for a short bit. When cold, they not only lasered deeper, but faster & cleaner. Not sure about the science behind it, but I've used that trick a couple times and it's been very beneficial.
    Tim
    There are Big Brain people & Small Brain people. I'm one of the Big Brains - with a lot of empty space.- me
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  8. #8
    Quote Originally Posted by Jeff Watkins View Post
    What lens are you using? That will play a major role in the results you get. The smaller the focal length the smaller the beam will be with higher power density. I use a 100x100 (f160) lens when I'm working with copper and certain types of brass. I try and arrange the artwork towards the back of my week area to limit reflections and scatter. Most of the time my 200x200 lens sits on the machine but I do change it when needed. Sort of like having a favorite camera lens but you still need the right lens for the job.

    I've been looking at the 70x70 (f100) lens for awhile and saw Kev recently bought one. I'm ordering one this week for tougher materials and a little time savings.

    I believe its 290mm focal lens. So maybe the beam isnít small enough to handle copper. Thatís frustrating!

  9. #9
    Quote Originally Posted by Tim Bateson View Post
    I had posted a couple months ago about having trouble with electrical Copper cubes. I placed a few in the freezer for a short bit. When cold, they not only lasered deeper, but faster & cleaner. Not sure about the science behind it, but I've used that trick a couple times and it's been very beneficial.
    Wow thatís crazy! I never would have thought to put the copper in the freezer. How did you even think about giving that a try? Iíll give it a try... thanks!

  10. #10
    A thought on focal length concerning fiber laser lenses...

    There's 3 'focal lengths' that are in play:
    1- the lens "F=" number,
    2- the lens working area,
    3- the lens actual focus length from lens to work...

    Most lenses are sold/advertised based on working area, a "110mm lens" means you have an approximate 110mm working area. But the lens F-number for a 110 lens is typically 160mm, which is the approximate outer-limits of the lens's full scan area.

    someone on the board taught me this (forget who, but thanks! ) - to find the scan area of a lens, take it's F number- say 160mm, and draw a circle that big. Now draw a box that fits perfectly within the circle. According to Corel, a 113.128mm box will fit perfectly into a 160mm circle

    I have 3 lenses, F numbers are 100, 210 and 300... The working area's calculate out to 70.7mm, 148.48mm, and 212.115mm respectively- These lenses are advertised as 70, 150 and 210mm lenses, so the box in the circle thing does work as a rough calculation...

    I don't know how to calculate focus length, other than to test the lens manually, there may be a math calculation?

    That all said, if you're indeed using an F-290mm lens, you're getting a lot of working area but the compromise is lower beam power density. A 110mm lens will focus to a much smaller spot and will likely more than double the beam power, which may get your copper to better...


  11. The math to figure out your actual working area: Example... F-theta mm number (210mm) divided by the square root of 2 (1.414213562373095) = 148.49mm
    Anyway, just remember to divide the lens mm x 1.414.

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