Print fails after first layer - hobbed bolt starts slipping

Hi,

I built new RepRap Prusa i3, but I have problem with printing.My prints still fails after sucessfull printing of first layer. On second layer my extruder suddenly starts to extrude less and less material and hobbed bolt starts overslipping more and more on filament, so filament stops moving. Then I always have to clean hobbed bolt... I also tested more types of extruder springs without success.

I tested temperatures from 235 to 265°C, but no change. If I try to extrude filamenet manually in RepetierHost on 240-250°C it works absolutely fine, I can extrude for example 10cm of filament easily and without any problems/slipping. Extruder steps are also calibrated ok (on extrude 1cm commad it extrudes exactly 1cm of filament).

I attached photos of first layer and hobbed bolt after fail...

Parameters:
Extruder: Greg's Wade extruder
Hotend J-Head nozzle 0.5mm (for 3mm filament)
Filamnent: ABS
Firmware: latest Marlin
Electronic: RAMBo

Edited 1 time(s). Last edit at 03/20/2014 05:10AM by dpalo.

how fast are you printing after the first layer?

60mm/s for infill (and layer height 0.2mm). I tried to change it to 30mm/s, but still same problem

looking at the second picture, looks like the hobbed bolt dosen't have deep grooves they get filed up pretty fast. (had this problem)
The otherthing I would see, is bed filament.. too soft.
Could be to much pressure on the compression bearing and sinking the filament in the hobbed bolt.

did you try to pass the filament by hand ? see if there is a restriction in the head.. (also had that problem before)




just my 2¢ but could be the problem.

If you air print does it still strip? Adjust your z endstop so it is well above the bed and run the same print job.

I had issues stripping on the first layer because the gap between the bed and nozzle was too tight.