Extruder extrudes, but print won't work

Hello all,

Another issue popped up between my prusa and its first print...
As I finally achieved the complete build of my prusa, got the right temperature table to be in a good temperature range, calibrated the e_steps per mm to have the right extrusion speed, etc, I can't get my printer to make its first print !

I have 2 complete different behaviors for my wade extruder on an extrusion test and on a print :
- When I launch an extrusion test in pronterface at 150 mm/min speed, everything works
- When I launch a print, extruder motor won't work at a constant speed. The behaviour I get is that the motor try to extrude for a couple of degrees then releases the pressure (causing the motor to go backwards). At the end of the print, no plastic is extruded as this behaviour is causing the extruder to clog.

I tested prints at various feedrates / flowrates (40, 75, 100), and got the exact same behaviour.

What could be the cause of my issue ?


To be more precise about my configuration :
- Prusa mendel with Wade extruder
- e_steps configured at 1350
- PLA 3mm filament
- pronterface with sfact
- sprinter firmware

Thanks a lot for those who might have an idea of what this is about

Raphaël

Are you running in absolute or relative coordinates? And have you matched firmware to software? Also the retract settings might be too high, but I'd check coordinate settings on firmware and software first. And there might be a need to zero your coordinates, especially the extruder, before starting a print if you are using absolute coordinates.

Thanks for helping me with this..

I am running in absolute coordinates, have the sprinter firmware 0018, and pronterface with sfact software (last version I guess)
My retract settings are 15mm/s.

I tested relative coordinates in the software, but it didn't work as well : the extruder motor turned forward and backwards for even shorter distances than before, but it didn't push the filament at all. After this test I think that software and firmware work in absolute coordinates.

Would it be possible that my problem comes from a wrong setting of my stepper drivers pot ?

I will retry that as soon as I get a new microcontroller for my sanguinololu... a shortcircuit between 12V and thermistor caused issues to it. I hop damages will be limited to microcontroller.

Raphaël

Are you sure your small gear is not sliding on your extruder motor shaft?

I finally found what it was all about...
After a few issues and a week of hollidays, the problem was very simple : I only had to adjust the extruder stepper driver pot to have a clean operation of the motor.

Thanks for your help

Raphaël