New Hex Hot End Stops Extruding Mid Print

Hey everyone,

I just installed a new hex hot end and made a few prints no problem. However I started noticing that about mid-end of the my prints the extruder would stop extruding and I would just get flaky bits.

I tried adjusting the two tensioner bolts and I loosened the bolt holding the carriage. I don’t think the nozzle is clogged because when I push down without the idler carriage the filament comes out fine. Then when I hit the extrude button everything seems to be fine also. But when I start a print it extrudes for about the first 20 seconds and thins out then nothing comes out again.

I thought my tensioner was too tight but when I loosen it it doesn’t extrude at all. Is the bolt supposed to eat into the filament so that it actually makes an indent into it?

What filliament are you printing, and if its pla in particular, is your new always on fan actually blowing still?

I’m printing ABS. Now that you mentioned the fan, I realized that the fan always was at 1%. I used the M106 S123 code to test and that was the first time I’ve seen that number on the screen change to anything but 1%! I went into Slic3r and chose fan always on, but I still had to type the command after starting the print to get my fan to start. I’m starting another print now and so far so good so I think the fan was definitely the issue. Seem the Slic3r code doesn’t do anything though and wondering if 50% is sufficient?


The heatsink fan is/should always on when the printer is on. You can usually hear the little blower. If you press the side of the blower, there should be a change in frequency.

Check that you’ve got everything aligned… extruder body, hotend plate (aluminum), and hotend. The screw holes on the aluminum plate are elongated which allows for adjustment, hence shifting. Best practice is to insert a solid 3mm rod in the hotend before assembling the toolhead… then remove the rod after everything is tightened down. A bamboo skewer (for BBQ, satay…) or a piece of filament will work also. Here’s the printhead assembly. And see ~1:27 of the video (which actually shows the budaschnozzle assembly, but should apply to hex… just slide the rod into the top of hotend, rather than all the way through).

ABS isn’t as prone to heat creep as PLA… if using PLA, folks on the Internet say that “seasoning” the hotend with olive oil / canola oil helps.