EMT Extension Monoprice Mini Delta (Flawed Design Read Notes!!)

prusaprinters

This is a failed attempt at making an EMT conduit based extension for the Monoprice Mini Delta. The original goal was to use 3/4" (18mm) EMT conduit as a support structure around the original aluminum frame of the MPMD to allow the use of 500mm x 8mm linear rods to extend the build height by almost double. Along the way I discovered a number of alignment issues as well as the fundamental problem that the carriage will smack into the upper braces when homing. In the end I decided that it abandon the project, but maybe somebody else will find the project useful. You might be able make it work by either printing new braces that bow outwards to provide clearance or finding a way to add braces to the very top. Although I was able to get things ridgid and straight enough to move, I would not recommend building this design as-is Materials needed: 3x 540mm cut pieces of 3/4" EMT conduit (I used RidgidModel 10 tube cutter 6x 500mm x 8mm linear rod 12 x M3 threaded inserts for alignment clamps Design Notes: The ridgidty of the original frame is set by how tight you pull in the braces and the top cover when tightening the set screws. This makes assembly and aligment a pain. My initial goal was keep this as much untouched as much as possible. Using the original top caps should keep spacing identical, the only issue then becomes aligning the tilt vertically. Because the geometry of the printed top/bottom caps should be identical in theory things should line up well. This seems to work, although there's nothing aligning the extrusion with the EMT rods. The clearance of the original frame is extremely close. An extra mm tilt in any direction is enough to cause the carriage to rub against the aluminum frame. You can get around this with printed carriage design with thinner walls. I went through several design iterations of an alignment clamp that sets the position of the extruded sides with M3 bolts. There is next to no clearance for the 4 top holes of the extrusion so I had to use the tops of the side braces instead. The EMT rods are meant to fit tightly into the top/bottom caps by friction. An M4 hole in the back is provided to tighten a set screw to prevent things from rotating. PLA tends to torque out so it'd probably be better to add a threaded insert to tighten things down. Print Settings Rafts: Doesn't Matter Supports: No Resolution: 0.3 Infill: 3x perimeter 16% Filament: Inland PLA Gold Category: 3D Printer Parts