M777 155mm gun in firing position (Various users)

thingiverse

This is a 1:76 model of the M777 that's used by multiple countries around the world. It's an extremely interesting and lightweight design for a 155mm weapon, making it a tough but attractive model to work with. The design was based on a face model provided in the SketchUp library by Devil Dog 204 et al., modified and significantly changed in SketchUp and 3D Builder through an iterative process. It took some time and several attempts to produce a version that's printable and can be assembled without major issues. Staying close to the original revealed problems with the links between moveable parts, making it unsuitable for use. I then split the design into its various components, but ran into issues with assembly and gluing... The result I'm sharing is a compromise, and seems to work reasonably well. Another 'secret' was to split cylindrical components like the barrel and supports longitudinally to ease printing, and I provide a dowel to assist in aligning the supporting halves, though this may not be necessary. Assembly can be a bit complicated, but it's perfectly possible if you glue the side supports for the barrel together first, then mount them on either side of the barrel assembly. The cylindrical ends of the support structures will likely need filing, as the printing process struggles with cylindrical objects. However, printing with fibers running longitudinally is best. The spring should be inserted in the lower pair of holes before gluing this assembly. The rear holes in this group then fit on the round pegs inside the trunnion part, and the gun (fixed in elevation) positioned using the spring and top cylinders. This complete assembly is then mounted on the carriage. I hope this makes sense... The wheels haven't come out quite as well as I had hoped, so I may look for alternative options that can be integrated with the assembly... There's a general problem importing wheels from SketchUp, as converting them to solids causes issues with open toruses. Still thinking about this. I plan to have a variant with boxes for the Leonardo LINAPS positioning system in due course, and one with the gun in towing configuration (which will require a different design approach). Hopefully... It's an interesting model; I hope it's liked. Enjoy! 5-12-18 Added an STL file that is the original derived from the SketchUp shell model. This should NOT be used for printing (it will be a mess), but is included to help with assembly. As can be seen, the original model was complex and challenging at this scale.