Multimaterial printing on the printer Pruša MMU assumes a gradual exchange of filaments of different colors. The Filament used for printing is redrawn back so that it can be replaced by another. The device uses the gravitational energy to wind the released filament back onto the spool.
Device is upgrade of HARTPA V2. Against HARTPA V2, the structure was reinforced with the rods from the jakl profile. This measure does not distort the frame by the coil weight. The connection to the pulley points of the printer has been adjusted so that the coil is directly connected using PTFE tubes.

Print instructions

1. Finished Parts
   Bolt M8 x 80 hex head with 2 pcs
   Screw Washer M8 2 pcs
   Nut M8 Low 2 pcs
   Screw 3x40 with countersunk head 2 pcs
   Screws M3 x 25 countersunk head 8 pcs
   Nut M3 8 pcs
   Screw M3 x 16 for hex wrench 2 pcs
   Nut M3 square 2 pcs
   Ball Bearings 8/22x7 4 pcs
   M10 x 25 hexagon bplt 1 pc
   Nut M10 1 pc
   Self-adhesive rubber boots 4 pcs
2. Drilling templates
   Print Parts
   • Driling template-Vertical
   • Driling Template – Horizontal
3. Production of bars for construction.
   • Cut bars from the jakl profile according to drawing “Horizontal bar. Pdf”, “Vertical bar. Pdf”.
   • The ends of the rods must be trimmed to be completely perpendicular!!
   • Drill all the holes to a diameter of 3 mm using drilling template. Drill holes for larger diameters and counterbore according to the drawing.
   • Cut the thread into the vertical bars.
4. Printed Parts
   Print from PLA
   • Vertical Frame
   • Horizontal Frame
   • Fasten Stop (set fill density to 75%) 2 pcs
   • Spinner
   • Arm
   • Guide
   • Holder
   • Nut
5. Assembly everything according to attached pictures
6. Connect the spool buffer to the printer with the PTFE tube
   Video:
   https://www.youtube.com/watch?v=otfgxMiwivw
   Open issue:
   The inertia of the coil sometimes causes the filament skip edge of the coil.