Printhead wiper


Since a short while, i gathered everything so i could continue my experimenting with dual extruders on a rapman 3.1 to print with support materials. I assembled everything back together and thats what it looks like.

Ofcourse printing with two printheads isnt easy, so one problem after the other come up. First i had to somehow handcraft some g-code files, to test-out how those print heads behave. As it is a boring job to manually edit huge g-code files, i made myself a small application which allows me to insert head-change sequences moving of coordinates and other things faster and easier.

With that i was finally able to print a first mixed object. But i noticed fast, that when one print head is not-active it will slowly leak some filament. Running the extruder backwords for a bit fixes that, but makes the restarting difficult. To restart the not-active extruder, you have to let it run a bit to make sure useable plastic is again in the nozzle. Its nearly impossible to run it exactly the right amount, so that the nozzle is filled, but nothing comes out. Also the plastic seems to degrade if it stays heated too long, so i needed a way to clean the nozzle after repriming it.

Thats what i have built:

It just holds some wires really flat over the printbed and the printheads have to go over the wires to leave the heatup postion. This way the wires sheer any leftover plastic from the print head so they are ready to print. Ofcouse this wiper is mounted on the side, so that it stays in place for a head-change at a higher Z.

This seems to work fine in the first test. We will see how it behaves in further experiments.