Prusa Mendel i2 - Prints Test Objects But Not Others

I have Mendel i2 and I'm using Pronterface and Skeinforge (from within Pronterface) for printing.

I have printed the calibration objects (e.g. the 20mm box, 50mm tower, etc) and everything works fine.

I'm now trying to print my first objects and am experiencing problems.

For example I am trying to print this (a fan mount) => [www.thingiverse.com]

however, the extruder does not seem to be pushing out any filament. I have actually put a mark on the filament and its not moving ... the extruder keeps moving (retracting and then re-extruding) but the actual mark on the filament is not moving through the extruder.

If I stop the print and re-load one of the test prints (e.g. the 20mm box) everything works normally.

I'm using Skeinforge to generate the gcode with all the same settings so I'm struggling to understand why the test objects print but not the others. Unfortunately the gcode is greater than 614K (zipped) so I can't attach, however I can extract parts and post if that will help.

Any suggestions would be most welcome.

Thanks.

James.

What happens if you install Cura and print your stl from there? I have got strange results sometimes with Pronterface + Slic3r on Linux.

edit: thingiverse things sometimes have errors.

Edited 1 time(s). Last edit at 05/26/2015 02:04PM by Plasteroid.

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Prusa i3, Ramps 1.4. Catnozzle 0.4mm
SketchUp - Enveloping Globoid Worm Gear - Part One - 3D Printed: [youtu.be]
DesignSpark Mechanical & more precise screw thread: [youtu.be]
Nicer Screw Thread In SketchUp ( Bolts,Nuts): [youtu.be]
How To Model A Heart Shape In SketchUp: [youtu.be]
How To Draw 3D Printable Snap Fit Ball Joint In SketchUp: [youtu.be]

I haven't yet tried Cura but I did switch from Skeinforge to Slicr and I get exactly the same behaviour.

I've marked my filament and when printing there is very little movement - the filament hardly moves through the extruder (although the extruder wheel is continually rotating).

That made me thing that the J-Head was somehow blocking up after a certain amount of time .... that could explain why I don't see the behaviour when printing the test objects as they are relatively simple. I therefore stopped a print that was failing ... reset the printer and tried immediately printing a test object again. It didn't work so there is some sort of blockage.

Is it possible that the extrusion rate is wrong and causing the blockage?

Thanks.

James.

Can you extrude from Pronterface 15mm or something I have speed 60mm/s? I do it alwas before starting to print or 3x5mm. Slipping Filament? Too cold hot end? Marlin or other firmaware extrusion speed too fast?

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Prusa i3, Ramps 1.4. Catnozzle 0.4mm
SketchUp - Enveloping Globoid Worm Gear - Part One - 3D Printed: [youtu.be]
DesignSpark Mechanical & more precise screw thread: [youtu.be]
Nicer Screw Thread In SketchUp ( Bolts,Nuts): [youtu.be]
How To Model A Heart Shape In SketchUp: [youtu.be]
How To Draw 3D Printable Snap Fit Ball Joint In SketchUp: [youtu.be]