Enhancements on the MegaPrusa printing with Polypropilene (PP)
1. Wiring of heated bed with 110v AC
Warming up 4 heating boards with 24 volts DC at 5 Ohm each uses 20 amp (480W), which requires a large power supply.
Solution: 4 normal heating boards were connected in series, from their 24V DC connectors (It would now need 96 volts to operate). They were glued onto the underside of the 3mm aluminum bed. The bed was grounded, and I connected the control of an external electronic relay to the 12v heated bed connector on the RAMPS board. The power source for the heated bed is 110v AC, with 605W consumption .
(I later realized that heating the bed is not so important with PP).
2. PP adhesion to the bed
PP will not bond to other plastics, or to metal or glass. Two alternatives worked:
a) I printed on a PP board (Can be a kitchen cutting board...)
b) Packing tape is very often made of PP (verify). Just replace your blue masking tape for ABS on the printing surface with Packing tape...
3. Using oversized PP welding filament
The national prosthetics center in Managua gave me bundles of PP welding filament, with a variable diameter of 3 to 3.5 mm. This would jam any 3mm head.
Solution: I widened the Throat and the Nozzle with a 3.5 mm drill, for my E3Dv6 Hotend.