Skelestruder V1 for Prusa MK3 and MK3s

thingiverse

Apologies for the delay on IR sensor support. I've finally received the backorder kit from Prusa and will get it out as soon as possible once I can test it. In the meantime, try this alternative: https://www.thingiverse.com/thing:3689971. I've done a beta release for MMU2s IR sensor support. Follow the MMU link below to access it. The first official release is in progress! After less than one year of development, I'm finally getting out of beta. You may want to add "watch" to this project, as I'm still making updates and improvements. For example, I've recently released a new hybrid sensor mod. New instructions can be found here: https://jltxplore.dozuki.com/c/Skelestruder_for_Prusa_MK3. I've moved these to their permanent home, but let me know if you see any issues with the transfer. Motivation: I wanted to see if I could create a lighter weight extruder that would unlock more speed on the MK3. I also wanted to try some new innovations, fix some nagging issues, and make easier adjustments while keeping the good bits from PR. Starting with a blank piece of paper, I solved the problems I saw and ended up with something related to e3d Titan and Bondtech BMG. But it's tailored for Prusa MK3, includes more features, and can be made yourself for much less. Project goals: Remove 200g of moving mass and center motor on belt-line to increase acceleration potential Keep build volume, e3d v6, Bondtech, laser sensor, and other goodness from PR Improve cooling and nozzle visibility Increase ease of use -> see Usage: https://www.ifixit.com/Guide/Skelestruder+for+Prusa+MK3+Usage+-+Tips/118012 Optimize parts for FDM printing -> RepRap spirit Purchase as little new hardware as possible * Lightweight motor: $8-15 (or use stock for free) * 5mm shaft: $2-8 * Belt loop: $1 * 3 bearings: $2 Main highlights: * Almost 200g less mass, centered on belt line * Increased print volume for V6; Or use Volcano with no loss in print volume * Filament sensor works with any color filament including clear (solved here first) * Shorter stack and free path to better handle flexible filaments * Tool-free rack-and-pinion PINDA mount adjustment * Tool-free quick-lock idler with tension adjust and manual load/unload * Improved part cooling from both sides * Full visibility of nozzle printing * Garter screw to keep V6 sock in place Supports (now or soon): E3d V6 or E3d Volcano Bondtech gear meshing better aligned with taller more central pivot Improved torque for pushing filament Decoupled motor so no heat transfer to filament Gearing + belt reduces stepper noise into print surfaces Easier X belt access for maintenance Larger, less restrictive path for Noctua cooling Multiple gear ratios supported. More on the way. Note 56/16 is most common. Tread | Pinion | Ratio | Esteps | -------|-------|-------|-------| 56 | 14 | 4.0 | 1120 | 56 | 16 | 3.5 | 980 | 56 | 20 | 2.8 | 784 | 54 | 18 | 3.0 | 840 | Short path animation shows how the filament has a short path from the cartridge to the inlet while traveling between the Bondtech gears. This better handles flexible filaments as there is no room to deviate. Also, the motor is not attached to either gear so there is no heat transfer. Witness: https://m.youtube.com/watch?v=gKRgGeHHhjM (Note: video shows older design, but performance is the same) No Firmware change required! However, you may want to make some changes for convenience. See assembly instructions. Indirect filament sensor does require a small change which is very simple. Weight | Stock | SPV1 | ---------|--------:-|--------:| Motor | 270g | 128g | Parts | 115g | 70g | HW | ~40g | ~30g | ---------|---------|--------| Total | 425g | 228g