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

thingiverse

This project was an unsuccessful attempt at creating 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, allowing the use of 500mm x 8mm linear rods to extend the build height almost double. Along the way, several alignment issues were encountered, along with the fundamental problem that the carriage would smack into the upper braces when homing. Ultimately, it was decided to abandon the project, but someone else may be able to 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. Materials needed: 3x 540mm cut pieces of 3/4" EMT conduit (I used the Ridgid Model 10 tube cutter) 6x 500mm x 8mm linear rods 12 x M3 threaded inserts for alignment clamps Design Notes: The rigidity 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 alignment a pain. My initial goal was to keep this as untouched as possible, using the original top caps to keep spacing identical. The only issue then becomes aligning the tilt vertically. Because the geometry of the printed top/bottom caps is 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 by printing a 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 and prevent things from rotating. PLA tends to torque out, so it'd probably be better to add a threaded insert to tighten things down.