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I'm still fairly new to 3D printing; got my Ender 3 V2 for Christmas last year. Recently the tension arm in the stock extruder snapped, so I bought and installed an all-aluminum replacement. My first successful(ish) print since installing it lasted two to three hours before I noticed the filament wasn't feeding. It had softened and clogged the lead-in to the Bowden tube just past the tooth gear. I figure the problem comes from (and what probably broke the original plastic) heat buildup; the new aluminum frame was VERY hot to the touch. I also noticed that the extruder motor was rather hot as well.

So you all know where I am: all I've printed with is PLA at 195 °C. Since changing extruders, I was getting over extrusion and dropped it to 185 °C and increased the retraction from 5 mm to 6.5 mm. The new one doesn't have (easily) adjustable tension, but the tension felt as strong as I had it on my old one, so I left it alone. I currently print within an enclosure, one of Creality's foil-lined ones since my printer is located in the garage (this is more for dust, but for longer prints I felt it was good to have since at the time it was getting very cold at night in the garage).

I don't think it's heat creep, since that meant it went all the way up the Bowden tube. My first guess is the ambient heat inside the enclosure. I am currently trying a new print with the top and side openings folded up to allow airflow. But I welcome more experienced suggestions and input.

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  • $\begingroup$ 185 is very low for printing PLA $\endgroup$ – Trish Mar 12 at 9:30
  • $\begingroup$ I think I was getting away with it because my printing enclosure held heat so well. I'm attempting to print outside the enclosure today to start removing variables to my problem, if it under-extrudes, I'll bump the temp up again. $\endgroup$ – Seradhe Mar 12 at 11:22
  • $\begingroup$ (185 is quite ok for several PLAs I have when printing slow.) Honestly, I couldn't believe that the heat can go up the heatsink and bowden tube to make etruder frame hot. So maybe your extruder's stepper motor is just geting hot heats up all metal elements (or a combination of both)? Did you replace only frame or also the stepper motor? Maybe the voltage is too high? I think voltages might be not calibrated well in factory, because my Z stepper in Ender 3 V2 also is getting really hot since I bought the printer (so far I added radiator, but I plan to regulate this voltage). $\endgroup$ – octopus8 Mar 12 at 20:13
  • $\begingroup$ I replaced just the frame. I wouldn't know how to adjust the voltage if that's the case. The new tension arm is a bit tighter than I had it set on my old, but I can't imagine it's making enough resistance to overwork the motor without seeing other issues first. $\endgroup$ – Seradhe Mar 12 at 23:46
  • $\begingroup$ I agree with your judgement. Regarding the voltage: first I am not sure if my copy of v4.2.2 mainboard has TMC2208 stepper drivers, or some older HR4988. I would need to determine that first, then find a valid formula for Vref. Actual voltage is tuned using potentiometer next to corner of stepper's small radiator. You can see here an example of this process. One problem is that Ender 3 V2 has the mainboard accessible from the bottom, so I would need something like garage pit to operate... $\endgroup$ – octopus8 Mar 13 at 8:00
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You could still get heat creep with a Bowden tube. It has different characteristics. Instead of jamming up in the direct drive, the filament can melt too far upwards into the heat break where it can refreeze and jam. The characteristic, if you can pull out the filament, is widened filament extending into the heat break.

See Air printing/jamming midway through raft creation

and

Understanding all the ways to avoid heat creep

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  • $\begingroup$ I didn't see any signs of Heat Creep when I pulled out the filament. The only softening I saw was in the direct drive; it had been pushed into a conical shape that plugged the port into the Bowden just past the gears. I'm still leaning towards an issue with the direct drive (is that what it's called? still learning the terms). the aluminum was too hot to touch and I had to wait 10 minutes before I could safely depress the tensioner and pull the filament out. That or the motor is overheating trying to pull Filament through... $\endgroup$ – Seradhe Mar 12 at 11:20
  • $\begingroup$ Is the motor driving the filament on the nozzle side of the Teflon tube, or on the opposite side of the tube? $\endgroup$ – Perry Webb Mar 12 at 12:14
  • $\begingroup$ It's on the opposite, mounted to the vertical frame $\endgroup$ – Seradhe Mar 12 at 23:43
  • $\begingroup$ How close to the bed? Or. close to any heat source? $\endgroup$ – Perry Webb Mar 13 at 2:50
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    $\begingroup$ sorry for the long delay, but I wanted to post a follow up to conclude this. I printed outside of my enclosure with no problem. Best guess is that the sealed enclosure wasn't bleeding off heat very well, and the aluminum feeder (being aluminum) was just soaking up the heat non-stop. fine for short prints but anything over three hours it would get hot enough to soften the filament. I'm currently printing housings for some extra PC fans I have and framing in a vent system to keep it from getting too hot in the future $\endgroup$ – Seradhe Mar 23 at 16:33

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