Marvin Printer

thingiverse

This project is still a work in progress. It's my take on The FlexMendel, drawing inspiration from TAZ printers but simplifying things as FlexMendel intended. The build volume measures 285mm x 275mm x 270mm. I've set the Z-axis to this height with my marlin firmware, but it could potentially be higher. The XY print area is limited by the mirror I'm using; a completely flat piece of glass would allow for a larger area. The extruder assembly was remixed from ffleurey's work, with modifications made to reduce sagging on the X-Rails. I rotated the motor 90 degrees and centered its weight over the rails as best I could. This improved things, but I still only get about 7-8 inches of reliable printing in the center of the platform along the X-axis. Most of the parts were built using 8020 hardware, which was readily available to me. Some STL files are up, but not all; I'll try to upload more as time and motivation allow. Print Settings: Printer Brand: MakerBot Printer Model: MakerBot Replicator 2 Rafts: No Supports: No Resolution: 0.3mm Infill: 30% Notes: Used a honeycomb infill pattern for added strength. Some parts were printed on the Marvin Printer once it was up and running. Design Background: I liked the overall design of FlexMendel, but I didn't have 2020 extrusions available. However, I had 8020 brand extrusion in their 1010 profile (1" square), so I recreated all parts in SolidWorks 2014. The STL files are posted here; source models aren't exactly the same because I've been designing upgrades and didn't save originals. For the extruder, I used a TAZ-style removable carriage, which replaced FlexMendel's carriage. This also allowed me to use the same X-axis rail width. To reduce X-rail twisting and available print area along the X-axis, I turned the motor 90 degrees and placed its Center of Gravity (Cg) between the rails as much as possible. Next step is upgrading X-rails from 8mm to 12mm. The print bed uses a TAZ model because I wanted a larger print area and had 12" square mirror panels leftover from a bathroom remodel. I also chose to use a NEMA 23 stepper motor for the Z-axis; this helps counter loss of position. Standard A4988 stepsticks work fine with the larger motor, with no overheating issues. To simplify motion, I used 8020 linear bearing pads (made from teflon) on both Y and Z axes. The extrusions seem very straight, so I didn't add additional rails or bearings for cost and complexity reasons. Originally, I used M8 threaded rod but found it too wobbly; I replaced it with step motors featuring 400mm long, 4mm pitch lead screws integrated into the motor shaft. These motors were worth every penny ($40 and shipping); they're a great upgrade. For Z movement, I swapped FlexMendel's machined sliders for 8020 sliding blocks on X ends and adjusted their width along with PTFE shims to take up most of the play. It's still a bit wobbly but pretty repeatable if moving in one direction only. The LCD mount is for thing 861091; check there for STL files.