• A Boat Hardware Project: And, Oh … for a Toolpath-Generating QR Code!

    by  • July 5, 2015 • News, Projects • 1 Comment

    A job well suited to Handibots is machining cut-outs for hardware items of one sort or another – – brackets, outlets, hooks, fixtures, lamps, switches, controls, handles, etc. My Handibot was particularly useful for just that type of job on a recent boat project.

    Project Details

    I had broken the pull-ring for a floorboard hatch on my boat. The only replacement pull that I could find was larger than the original hardware and needed a larger cutout. Marine hardware is a particularly good example of parts that frequently need specialized cutouts for mounting in bulkheads, decks, and panels. Here’s my new part and the floorboard, with the old hole, that I needed to put it in. You’ll note that the necessary hole for this part is actually a 3D pocket type of thing, not just a cutout in a panel.

    My floorboard with old hole and new part.

    My floorboard with old hole and new part.

    The Toolpath

    We can hope that, someday, manufacturers will be providing machining information that will allow “smart tools” like Handibots to quickly machine a mounting area or cutout for their product – – perhaps after just allowing us to scan a QR code on the packaging! Someday …

    Out of perverse curiosity,  I wrote the manufacturer of my part asking for a CAD or CAM file… I think they thought I was joking. Thus alas, no instant toolpath. And, in fairness, as the part was probably made with an old, pre-digital, casting it is not surprising that they did not even have a CAD file for me. So what would be the best and fastest way to create the new, 3D, cutout shape for housing this pull-ring?

    Someday, we'll get the needed cut-out from the QR Code on the package or part.

    Someday, we’ll get the needed cut-out from the QR Code on the package or part.

    Scanning the part did not seem the best approach. In the absence of a ready-to-run tool-path from the manufacturer, scanning or digitizing the part and creating a tool path from the new digital model would be one approach that could be useful for a lot of cut-out jobs. In this case, I didn’t think scanning was right. To scan, I might use a service like the 123D-Catch-tool provided by Autodesk. Using 123D Catch would involve taking a number of pictures of the pull-ring from many different angles, uploading the images to Autodesk’s cloud server … and a little while later, receiving back a 3D model. The 123D Catch system is pretty cool and it’s free. I’ve had it work well in a number of cases. For the back of the chrome pull-ring, to get a good model, I would have probably needed to first spray-paint a matte color to prevent miss-cues from all the reflections.

    A more physical approach to scanning would be to digitize the part with something like the ShopBot digitizing probe that can be chucked up in a Handibot and, using the “CopyMachine” tool [TC] in the software, can produce a surface map my touching off the surface in small increments.

    The problem with both modeling approaches is that they are a bit overkill and they prioritize getting the shape of the back of the part perfect. I wanted to prioritize getting a crisp, perfect fit where the pull sat in the surface of the floorboard. I didn’t really care about the shape of the hidden, back-side of the pull ring as long as I took out enough material for clearance.

    So, just using conventional CAD to CAM seemed the most straightforward. I used calipers to measure the diameter, depth, and other details of the pull-ring and focused on making a perfect countersink for the outer ring. To accommodate the sunken part of the pull, I just made sure I pocketed out deeply enough for good clearance. I used the V-Carve Pro software that is shipped with Handibots to draw the machining perimeters; then tool-pathed with its CAM functions. This gave a machining path that looked like this in preview.

    Tool-path inV-Carve Pro.

    Tool-path inV-Carve Pro.


    The simulated pocketing.

    The simulated pocketing.

    Machining the New Hole

    Since I could not afford to mess up my only floorboard, I did a test cut in a scrap before attempting the real cut … it looked good. So I moved on to the real piece.

    Practice cut ...

    Practice cut …

    When I created the toolpath, I set the 0, 0 location to the center of the part so that I could use the “Laser-Site” accessory to position exactly over the old hole — except I moved it forward slightly so that I could machine over a slight tear-out in the wood from the previous work.

    Using Laser-Sight to position the cut-out.

    Using Laser-Sight to position the cut-out.

    Then I was ready to do the job. Here’s a little video of the cutting.

    With the final, perfect fit, in the floorboard.


    One Response to A Boat Hardware Project: And, Oh … for a Toolpath-Generating QR Code!

    1. Mark Evans
      July 5, 2015 at 2:59 pm

      Great article Ted,

      I am glad to see I am doing my inlays for parts the same way you guys do. Amazing what you can do with a pair of digital calipers, a six-inch rule, and a notebook.

      I’ve have been inlaying plates for Kreg clamps this way, as well as making the plates.

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