Filament jams - Bulldog XL & E3D

Hi all,

For the last two weeks or so, I've been really, really pleased with the XL and my E3D. It's worked well and I've had no problems with either PLA or ABS until just recently.

It seems that after I get, oh maybe an hour or so into a print, the XL starts to jam. What I'm seeing is that the filament is getting kinked up inside the XL. Sometimes if I'm near, I'll hear the "click" noise it makes as the hobbed pulley starts to slip against the filament (ABS doesn't click, just PLA). If I'm _really_ careful, I can usually get in and squeeze the idler assembly by hand and pull back on the filament, that will clear the jam and not interrupt the print.

I checked the basics; Filament size is good - 1.6 - 1.9mm, and a nice round shape. Temp on the hot end is good, the nozzle appears to be clear, and I'm not "leaking" filament around the heater-block, feed tube/heat-sink assembly, or around the nozzle. I made sure the hobbed pulley is clean as well. I even disabled retraction settings in the slicers, thinking maybe that had something to do with it.

The ONLY thing I can think of is that I've noticed the E3D is "loose" in the XL. I'm not sure what's going on there, but it appears that somehow the pseudo-groove-mount opening is somehow larger than it was before. I had some trouble getting the E3D out of the XL, and had to twist it as I unmounted it (i had to replace a bearing on my X-carriage). Now, what used to be a tight fit for my E3D and older J-heads is quite loose (loose enough to see the hot end move UP by a mm or so during a retraction). Not sure that's the culprit.. but I'm starting to lean that way.. (I wonder if I can just buy a replacement for the machined parts on the XL rather than a whole new one)

I just pushed some "custom" firmware into my controller board to get the hot-end up to temp, and stuffed a thermistor down into the inlet for the hot end. I'm going to let that run overnight and collect the readings every 15 minutes or so to see if things are too warm at the hot end inlet side.. maybe the plastic is getting soft too soon...
Anyway, I'd appreciate any suggestions or pointers! This just started happening in the last few days or so.

Details on my setup are below.
Prusa i2
Bulldog XL extruder
E3D Hotend (direct drive setup), .35mm nozzle
Azteeg X3 controller, Repeiter v091r6 firmware

Is the fan running on the hotend full speed all the time? My E3D stays cool above the heat break when the fan is running

I added this to thingiverse the other day to address the fit of the E3D in the bulldog. [www.thingiverse.com]

I had a similar issue with my bulldog when I first began working with it. I believe its was primarily an interface issue with the hot end. That, combined with retraction caused it to bind as you described. Ultimately, I bought another hot end.