Consistently clogging in the Bowden tube

[dadinfinitum 0]

I have a Creality CR-10 Mini, and I've had a constant problem of filament clogging in the Bowden tube. I've gotten through entire spools with no problem, but then sometimes it'll print for an hour when a clog occurs. The stepper gear will start slipping since it can't push any filament in, and if I try to manually push/pull the filament, it goes nowhere.

 

I've ran filament at various temperatures, I've used different brands of filament, I've used different Bowden tubes. I check the level of the bed before each print, and when I connect the Bowden tube, I keep the nozzle unscrewed about 1-2 turns, push it as far as I can, and then screw in the nozzle. I'm also very careful to square the tubing before putting it in. I've cleaned the stepper gear with a toothbrush and alcohol, too.

 

I don't know what the cause is, and I don't know what to do. I'm running on fumes trying to figure it out, and any help would be appreciated.

[GregValiant 1,259]

15 hours ago, dadinfinitum said:

...and when I connect the Bowden tube, I keep the nozzle unscrewed about 1-2 turns, push it as far as I can, and then screw in the nozzle.

I think that's too far.  Try 1/4 - 1/2 turn instead.  With 1-2mm of the Bowden tube sticking out and getting squished when you tighten the nozzle, the inside diameter of the bowden tube will get squished smaller.  Prints with a lot of long retractions will move soft material into that necked down area and cause a blockage.  Prints without a lot of retractions don't seem to notice near as much.

[dadinfinitum 0]

43 minutes ago, GregValiant said:

I think that's too far.  Try 1/4 - 1/2 turn instead.  With 1-2mm of the Bowden tube sticking out and getting squished when you tighten the nozzle, the inside diameter of the bowden tube will get squished smaller.  Prints with a lot of long retractions will move soft material into that necked down area and cause a blockage.  Prints without a lot of retractions don't seem to notice near as much.

 

Thanks for the insight. I've also been told to check my fan settings. Here's hoping it works.

[GregValiant 1,259]

The hot end fan runs 100% and continuously so there aren't any settings for that one.  The layer cooling blower is adjustable and if you have a beastly blower installed and it blows on the nozzle too much it can cause hot end problems.  The stock one shouldn't be causing issues.

[jsilander 0]

Have you checked to see if the main hot-end cooling fan is working while you are printing?

 

I've been have the same type of issue with my CR-10. I started to get heat creeping up the Bowden tube and clogging it. I've tried a few different things and tests some small prints and found the the hot-end cooling fan is not turning on during print.

I have tested the unit and when I do a normal preheat the fan is on a t all time. once I try to start a print the fan turns off. I've tried to turn on all the fans manually in Cura to no success. I've been using Cura for a couple years now and just started having this issue in the last couple months.

So far I've had to replace my hot end because the original one got so badly clogged with plastic I couldn't fix it. I done' know how many nozzles I have clogged and Bowden tube I have gone through.

Going to be running a new test and turn the fan on manually to see if that work. I'll keep you informed

I'm running a Creality CR-10 V1 and using Cura 4.8

[GregValiant 1,259]

The hot end fan is hard wired in the "On" position.  When the printer is on, the fan is on.  There are no controls for it, there are no Gcode commands you can send that will effect the RPM, or turn it off or on.

If it's turning off by itself I think you may have a problem at the mainboard and it might be as simple as tightening the screws that bind the wires for the hot end fan.  Check for any chafing along the length of the hot end fan wires as well.

 

I was never able to overcome the heat creep with the stock hot end.  Eventually I stripped the threads for the nozzle on about the 500th time I pulled it out to clean it.  Although a heli-coil insert worked as a repair, I bought another stock hot end.  Same problems.  Now it's a Micro Swiss.  Not perfect, but a lot better.

 

One of the problems I had with my Ender (same print carriage and hot end assembly) was the mainboard fan.  It IS wired to turn on and off with the layer cooling blower (not variable speed, just on-off).  I printed a lot of PETG with the cooling blower turned off to avoid warpage, the mainboard fan didn't turn on, and eventually the mainboard components would overheat.  The fix for that was to wire the mainboard fan to the terminals of the hot end fan - because it's always on.

 

Eventually I designed a deflector that fits inside the hot end housing and directs the flow from the hot end fan at the heat exchanger.  That wasn't enough.  With a 3mm shim behind the hot end housing mounting surface, a 4015 ball bearing fan will fit into the housing.