@dsherburn, the Devlin designs are great; I do love his work, and he is one of the great grandfathers of the whole Stitch n’ Glue movement. I have not used QCAD, but I think I may just try it out (I’m never wedded to any particular application)! For the puzzle joints, there are two ways to go about it, both of which involve simply making a gently-curving spline. First, I lay out that series of S-curves (or back-to-back Cs) by eye; no measuring other than ensuring that the curves will not bind up the cutter by being too tight. Next, I just lay that curve over the panel objects. Depending if the panels are ‘surfaces’ or ‘bodies’ (insert your CAD terms of choice, here), I either split the surfaces with the puzzle spline and then extrude the two surfaces or I extrude the one panel and make a surface out of the puzzle spline by extending it normal to the panel…then using that surface as a cutting object. Does that make sense?
@MidnightMaker, that is awesome about starting on a Passagemaker. I once built up a CLC Northeaster Dory from the purchased plans: laying out the wood, scarfing the panels, connecting awl marks with a batten. Tiring work just to draw curves on the plywood! The CNC would have chopped off about 20% of that time, even with input of data (if it were available in offset tables, that is). As for accuracy, I did find that it does drop off at the ends (R/L) of the board, and consequently my puzzle joints needed a bit of helping and putty. No biggie, though. Fortunately for me, most accuracy nits were on the ‘oversize’ end, so I have to saw/sand down. For that, I am thankful. I am trying to make up a diagram of all of the inaccuracies observed, but building is taking my free time! I ordered a triangulation kit a while back on Etsy, and am still waiting for it; I have the stock sled setup, currently.
For plans, I got mine from the URL that you mentioned (Payson’s Instant Boat web site). That’s the place. I also have Payson’s book, “Building the Instant Catboat,” which is really good, but I actually have some additions I’d like to make to it from my experience building other boats (e.g. epoxy the interior of the centerboard trunk before slapping it together)! Doing paper edge as baseline would be good, I think, for your plans conversion. That, and taking a photo (and unwarping it in Lightroom or similar to make it a true orthophoto) and using that as a guidance background image may help.
For anyone wondering just WHY I decided to go CAD/CAM and do all of the legwork when cutting out the panels by hand is fine, here is one of the biggest reasons (besides the fact that the whole Maslow ‘movement’ kicks butt and I like machinery): SPACE. My workshop, which has birthed (berthed?) about half a dozen watercraft, some 17’ long, is teensy tiny. I could never have a lay-up like the Bobcat, now, and still cut panels. The Maslow lets me put that whole operation up against the wall (which I have to watch out for when walking around the 'cat) and frees up precious floor space. As for panel assembly, I can always lift the boat on sawhorses and do that beneath it. I would never do that and try cutting out panels. Maslow makes my use of incredibly small space so much more efficient. I could, I suppose, go outdoors and cut, but it is currently 20 degrees and there is snow in that area. A no-go for me.
Now, then, if I could ever clean up my space, it would be more efficient, but I get off topic, there.
