• Free stock for your laser!

    Peter Walsh11/01/2020 at 16:23 2 comments

    Political signs make great cutting stock for CO2 lasers, and starting Wednesday you can get a boatload of them for free!


    The official term for the stiff material is "corrogated plastic"(*), and it's basically corrugated cardbord using polypropylene instead of paper. It's light, stiff, strong, and waterproof.

    Here's a desk organizer made from it. The pieces were lasercut and then hot-glued together. (Then glued to a wooden base.)


    Here's a closeup showing the corrugation style of the board.



    Some older types might be PVC, and you shouldn't cut these on the laser, so be sure to perform a flame test on anything you find before you start cutting. Modern signs should be polypropylene, which is fine to cut.

    (*) Some trade names:  Cartonplast®, Polyflute, Coroplast, FlutePlast, IntePro, Proplex, Correx, Twinplast, Corriflute or Corflute

  • Connecting USB lasers to linux

    Peter Walsh10/16/2020 at 16:01 0 comments

    Overview

    This post explains how to troubleshoot and fix USB laser cutter connection problems on linux.

    More specifically, if:

    • You have a laser cutter
    • Your cutter communicates via USB
    • You are trying to communicate with linux
    • Your software cannot talk to the laser

    ...this post will take you through the steps needed to troubleshoot the problem.

    Step 1: The Quick Fix

    If you are reading this post for the first time, see if this fixes your problem.

    In a command window, type:

    > sudo usermod -a -G dialout $USER

    Enter your password when prompted, and if no error is shown reboot your system.

    If your software now works with your laser, you're done: It was a permissions problem, you fixed it, you can stop reading.

    (Note: enter the command literally as shown, including the $USER field. $USER is a variable set by the command prompt containing your login name.)

    If this does not fix the problem, the next steps will help you identify where the problem is, and give some suggestions on how to fix it.

    Step 2: Hardware/Electrical

    The first step is to check the physical USB connection to your laser.

    With the laser disconnected from your computer, in a terminal window enter "lsusb" to list the USB devices. (Note: "lsusb" is one word, no spaces.)

    Without rebooting, connect the laser to your computer and enter "lsusb" a second time.

    Look for an extra device in the USB listing, one that appears after you connect your laser.

    For example, on my system I see the following:


    Before:
    
    > lsusb
    Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
    

    Bus 006 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 005 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub

    After: > lsusb Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

    Bus 006 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 005 Device 002: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC Bus 005 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub

    When I connect my laser to my linux system, a new device of type "Future Technologies USB-Serial" is seen by the system, and all is good.

    If you do *not* see a new device line (of any type) when connecting your laser, you have an electrical or physical problem with the USB connection.

    Some things to try:

    • Check that your laser is turned on (doh!)
    • Verify the USB cable is seated properly: jiggle the connectiors, swap the cable end-for-end
    • Be sure the USB connector at the laser is connected to the USB port and not the UDisk port
    • Try a different USB port on your computer (sometimes they burn out)
    • Try a different USB cable
    • Try a different computer/laptop
    • Be sure your laser is configured to communicate by USB and not, for example, by network with USB communications turned off
    • Be sure your computer and laser are plugged into the same outlet, or same outlet strip (grounding issues)
    • Ask your laser vendor for help

    Step 3: Device drivers

    If your laser is shown on the USB listing, the next step is to see if the system is using the correct device driver.

    With the laser disconnected from your computer, in a terminal window enter "ls /dev" to list the available system devices. (Note: "ls /dev" is two words, with space between.)

    Without rebooting, connect the laser to your computer and enter "ls /dev" a second time.

    Look for an extra file that appears when you connect the laser.

    For example, on my system I see the following:

    Before:
    
    > ls /dev
    bsg dvdrw i2c-4 loop6 ppp snapshot ttyS14 ttyS26 uhid vcs5 vhci
    
    After:
    
    > ls /dev
    bsg dvdrw i2c-4 loop6 ppp snapshot ttyS14 ttyS26...
    Read more »

  • Etching anodized aluminum

    Peter Walsh12/24/2016 at 02:38 0 comments

    Laser etching anodized aluminum

    One thing we teach in the laser authorization course at my hackerspace is that the laser will remove the anodization from aluminum.

    The laser won't touch the aluminum metal, or any metal in general(*), but etching away the anodization is sometimes useful when you want to put your logo on a finished project, or for front panel markings.

    The process does not remove *all* of the anodized layer, so the end result is a slightly tinted aluminum against the anodized background. In other words, the process does not result in perfect contrast of the image against the anodized background.

    Still, it's something you can do with the laser that will give your project a professional, polished look.

    You can purchase anodized aluminum plate (and many other forms) on eBay.

    (*) This is not strictly true, but it's against house rules to try, so we tell people that the laser won't do it.


    Christmas for Frankie

    So when my grand-niece had her water bottle stolen and her mom suggested I get her a new one for Christmas, I made personalized versions. The results are shown up top.

    She's studying genetics doing research on viruses and fruit flies, so one bottle has a virus capsid, one bottle has fruit flies (which doesn't photograph very well), and one bottle has Alice and the caterpillar.

    Each has her name engraved along the bottom, so they're less likely to be stolen.

    [HA! I just now figured out how to make Hackaday.io break paragraphs at the image boundary. Take *that*, Hackaday!]


    Speed and Power

    Scan speed is 350mm/s, scangap is 0.15mm which is about 3 scans per line with our laser's 0.5mm line width.

    Remember to turn OFF bi-directional scanning to avoid any backlash in scan positioning. Turn ON bi-directional, and the left scans will be offset from the right scans by backlash in the mechanical system, making edges look like saw teeth. Probably not what you want.

    The power reading of 50% for our aging 80-watt laser probably translates to about 25 watts(*), convert as needed for your system.

    (*) Our unit mins out at about 25% due to the age of the tube.



    Positive and Negative

    Be careful with the positive- and negative-ness of the image. The "Alice in Wonderland" image is originally black on a white background, but the etching removes the darker anodization to reveal the brighter aluminum.

    The Alice scene thus became a sort of "X-ray" version - I should probably invert the image and make another one, but I ran out of bottles.


    Engraved Closups

    The accuracy of engraving is pretty good, considering the spot size of our laser is .02" to begin with. The line on the right is freehand from the image; ie - it's not a computer-drawn straight line.

    The aluminum metal has a slight bluish (left) or greenish (right) tinge from leftover anodization, because the engrave process doesn't remove everything.

    It would be interesting to see how the anodized/etched sections respond to chemical etching. Chemical etching might be an interesting hobbyist way to make complex thin aluminum pieces using a laser cutter.