Hi,

Just a short introduction:
My name is Batist Leman, I'm studying industrial engineer automation at the University College of Ghent in Belgium (HoGent).
This week I have proposed to make a reprap next year. We would be working on it in a team of 5 students, of which 3 students automation and 2 electromechanics.
Hopefully the project will be assigned, so we can share our findings.


That said, my question:
I was just wondering, isn't the angled motor in the extruder causing any variable angular speeds?
It seems the steel wire is functioning as a universal joint, no?
This is what I mean: [en.wikipedia.org]


Thanks,
Batist.

No it doesn't have the effect on angular speed that a universal joint does.

As long as the torque is constant both ends rotate in unison. The only way one end can rotate relative to the other is if it winds up, or unwinds the wire. That only happens if the load is varing as it rotates.

E.g. my first attempt at making the drive screw had excentric bearing lands. As it rotated it had to open and close the pump halves a little against the springs. That caused the torque to rise and fall each revolution which caused the cable to wind and unwind a little giving a variable angular speed, which modulated the filament width.

When I fixed the drive screw it gave a constant angular speed. Having said that I have replaced it with a straight drive because the cable wears out after a few tens of hours use.

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[www.hydraraptor.blogspot.com]

Ok, thanks for the reply.