Another Scotch Yoke

prusaprinters

<p>This is a redesigned Scotch Yoke mechanism. I had posted a non-printable sample design some time ago. Recently another Thingiverse user, Sprik, had generated a nice printable design. I made a couple and they worked very well, but the design relied on printed round pins to hold things together. This resulted in a final assembly that I thought was a bit fragile. Also, the tolerances needed to make the pins work on my printer were pretty loose. This made the yoke and end pieces rattle quite a bit, and the whole assembly would fall apart pretty readily unless glued together.</p><p>The attached design, which may feature some of the worst OpenSCAD code ever, addresses these issues.</p><p>Thanks for the great inspiration, Sprik! Your design is very nice!</p><h3>Instructions</h3><p>A plate file is supplied, with everything in a nice printable orientation. The plate file includes (2) Main Shafts, both for breakage and to keep the ends a bit cooler while printing.</p><p>All of the parts I have done so far are in PLA, and they've worked out quite well. If you don't have a fan on your hot end, I suggest setting up a fan to blow across the print bed once the first couple of layers are down.</p><p>I make use of the differential fill pattern and density features in Slic3r to make the Yoke and Main Shaft with a rectilinear pattern at 50% density. Everything else can be 20% density. If your filament is a bit translucent, playing with different infill patterns can make the Crank and Base a bit more attractive. The "extra" hole on the crank is there to allow a dowel or M3 screw to be added, either for reinforcement or a handle.</p><p>On my Printrbot Plus, the current OpenSCAD file generates parts that fit together nicely, and stay together without glue. The only parametric thing in the file is the clearance value - change that as necessary for your use. You can generate individual parts by invoking their name in the OpenSCAD file - it should be pretty evident where.</p><p>The OpenSCAD file is pretty ugly - sorry about that!</p>Category: Engineering