155mm Howitzer Shell

prusaprinters

<p>This is the standard 155mm howitzer shell in use by the US army since around WWI. This model was inspired by @sbeecroft's models on Thingiverse; this is not a remix, but a ground-up CAD model off the US Army's 1994 procurement specs. However his model doesn't fit on the prusa (if you have a gMax sized printer I recommend his, or if we ever get our i3max!!). Also note, he sells pre-made ones of these, which look amazing.. I glued the sections together using 3D Gloop for PLA.</p> <p>Note: Unlike @sbeecroft's model I was never thrilled with how the screw threads on the fuse worked, (likely due to the issue of the fuse being SLA printed and the shell being FDM), so I made the fuse glue-in (I used epoxy)</p> <p>The painting was complex, and I used a variety of paints, including the flat-army-green spray which matched the spec'ed color, along with the flat-yellow (CAT yellow). For masking I used the included mask which I laser cut is laser safe masking material (laser safe critcut sheets) which I use movable spray adhesive to place (note make sure it sticks well if you don't want to be doing hand touchups). Krylon makes a nice copper spray paint I was able to get at Home Depot for the copper rifling band.</p> <p>I have included the reference artwork I got for the fuse painting. I used acrylic red with a very fine brush for the next and screw indicator. To be honest I needed to touch it up with a red fine-point sharpie for it to work.</p> <p>I ended up putting about 15lbs (6kg) of cement in the base as it kept tipping over. The fins are designed to grip the concrete so it doesn't shift around. When you glue each section together (I used 3D Gloop for PLA) you will need to use model putty to get a nice smooth finish.</p> <h3>Print instructions</h3><p>Each section is designed to have a print surface (the one with the holes, not the alignment spikes. The bottom obviously prints base down. Note, I printed the fuse on a SLA (Form 3) as the lettering and screw won't show on FDM most likely, in a gray resin (although since you are priming it doesn't really matter).</p> <p>Note even though you may be tempted to just use the army green PLA as is, it's too glossy and you need to sand the model to get rid of layer lines anyway; and if you use putty for the joints it won't work anyway: I used Tamiya model putty. To me the advantage of the army green PLA is if the paint gets scratched it will reveal green rather than some random color.</p> <p>I used the stock Prusaslicer 0.15mm Prusament settings, with 15% gyroid infill...</p>