i3v Cura settings

[printbus]

What were the signs during extrusion that the filament was being ground up by repeated retractions? I'm guessing this is also work-piece specific issue. I would like to find a way in the Cura visualizer to flag / highlight the retractions in the toolpath view.

The indicator was that the extrusion would just stop, and when I'd abort the print and pull the filament, the hobbed bolt had chewed into it. Everything would go fine for a while again after reloading the filament and restarting. This is definitely work-piece related. The recent print where I battled this was on a 4-in x 4-in project box with 1-inch high sidewalls. Posts with screw holes for a lid in the four corners. At some point in the sidewall layup, the extrusion would just stop. Predictably. Took a while to rule out bad filament, too-low temperature, too much cooling fan airflow, too much spring tension on the extruder, etc. I eventually realized that corner-to-corner moves were involved in Cura completing the screw posts in the corners, with a retraction on each move. The filament apparently couldn't hold up to the repetitive action of the hobbed bolt rotating back and forth for the retractions over such a short length of filament.

I'm not aware of a way to explicitly view the retractions in Cura. You can see travel moves, and indirectly perceive a retraction for each move longer than the retraction_min_travel setting. When I want to really see details in the slicer output, I usually bring up the gcode in http://gcode.ws/ and look at layer info. Slider bars allow you to select different layers and follow the nozzle move around the layer.

Actually, it was viewing the slicer output in gcode.ws that finally told me what was happening with the box. I had both print and travel speeds at 100mm/sec, and watching it print I just assumed the multiple loops around the print were just printing the wall. As soon as I saw the corner-to-corner travel I realized what was probably happening.

Cura was only recently added to Repetier Host as part of their v1.0 baseline - maybe a month ago. Understood on the Mac and Linux constraints.