Spoke too soon! Return of the weird hairballs! (pics included this time!)

[Patrick Brinton]

MM2, Bridge Nylon. Hotend 260 all layers (tried lowering, will not print. Also am not confident thermistor is correctly reporting temp. This temp is the lowest that will successfully print) Bed 70, good adhesion with Uhu blue glue stick. e3d v6 hotend with fan on its heatsink always running. No fan on the print itself. Printer enclosed in a box, temp inside box around 40C. Pic of overall setup included.

Here is what is happening: First few layers print out perfectly, then suddenly it makes a bunch of little hairballs all over, (see first pic) and the flow stops. Extruder carries on merrily, but nothing comes out. When I pull out the filament, it looks like the second pic. The extruder has made a kink and the end is white and a little swollen.

At first I thought it might be a filament delivery issue, but it will extrude strongly against a considerable upward pressure on the filament, so it is definitely not that.

ideas?

[Michael Anton]

Do you have a place in the filament path where the filament is not supported?  If so, is that where the filament kinked?  If the filament is somewhat flexible (like nylon can be), and there is an unsupported place in the filament path, it can cause a jam, and exhibit the symptoms you have seen.  I found this out when I first started printing NinjaFlex.  In my case, there was a 5mm high void between my J-Head and the extruder that the filament would get caught in.  I printed a 5mm thick washer to fill the space, and it worked much better then.

Mike