I´ve done a lot of tests...
One of the first tests was a test of the second extruder. The motor was driven continuesly, and the syringe was stand-alone, pushed by hand.
Should work. Should...
For this test i used a mixture of corn-fluor and water. If you ever want to test something with pasteus-materials, don´t take corn-fluor!
If the mixture gets under pressure, the fluor makes little pieces that clogs every hole smaller than 2mm.
The result: you give a little bit more pressure on the syringe, the hose between sysringe and extruder bursts, and your whole working-room is dotted by a corn-fluor-water-mix. Dooh!
Second test: instead of corn i used some chocolate-creme. Turn the motor on, motor should move. should...
After a few seconds some smoke came from the board. What happend? The board wasn´t mounted already but was lying on the table.
And below the board lyied a little screw, make a short between the motor-current-wire and ground. Dooh!
I fixed the wire (5 hours to presentation) and made a new test. This time everything worked fine, but the screw inside of the second extruder is not running fine in the case. A flexible coupling would be better...
After mounting everything i made a new test:
This time the syringe was actuaded by the dc motor. For minute everything worked fine, but then the pressure on the syringe was to much for the printed motor-holder. The printed-part between the trapeziodal-screw and the syringe getted in a bad angle, and flushed out of the syringe.
Reason for this was the printer-nozzle. It´s diameter was too small for Nutella on 60 degrees.
So i removed the nozzle and with a 3mm hole the extruder works fine, but not very acurate.
In the conclusion i would say the project was a success. But some smaller changes are to be made: