• Test punch card punched

    spencer • 05/21/2016 at 21:16 • 3 comments

    So, a punch card reader isn't really going to be that great without some punched cards to read.

    However, I don't have any punched cards.

    So, off I head to Lasery McLaserface* to make some!

    Now, of course I didn't just click the "cut punch card" button on the laser cutter. Things are a bit more involved with that, although one of the main goals of this project is to automate the the process of turning a text file in to a bunch of laser cutter ready .dxf files.

    What I actually did was go to http://www.masswerk.at/keypunch/ and typed a message. From there I could download a .png file of a punch card

    All of the cutouts are transparent, so from there, I used Imagemagick to convert it to a black image that retains the transparent sections.

    Potrace should be able to trace the edges of the image and create a dxf - however, it doesn't like .png files and even as a bitmap I couldn't get the output right. So I used Inkscape (which has Potrace built in) to do this bit.

    The .dxf looked good, and came out pretty well - although some of the holes had just the tiniest whisker of card holding the chad on. At 97mm x 255mm it is bigger than 83mm x 187 of a standard size card, but at least it gives me something to get started on.

    As mentioned earlier, automating this side of things is will be key to this project. I don't consider myself fluent in Linux command line syntax, but I know it *should* be able to read a text file, convert it to hexadecimal strings, send that to a web page in an appropriate amount of chunks, download the resulting images, modify them and produce a single dxf file containing all the cards needed to be made. All I have to do is teach myself how to do that :-)

    * Lasery McLaserface is the name of the laser cutter at Nottingham Hackspace