I'm doing some 1 hour prints and to prevent the extruder from stalling/skipping I

3D Printing
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1

I’m doing some 1 hour prints and to prevent the extruder from stalling/skipping I added the big fan to blow at the aluminum. 1/2 way into the 3rd print it jams up! I cannot for love or money pull the filament back out.

Cranked the head temp up 10 degrees, turned off the fans and after a few minutes I was able to feed filament again.

The big fan has been retired. I’m trying the little fan - precariously propped between the top heatsink and the wood frame…

Once I’m done making these Stevenson screen rings (I’m almost out of white filament), I’m going to print a proper fan holder.

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2

Well scratch that - it just jammed again… Heating to 210 (normally at 200) and waiting for it all to melt and start flowing again.

3

What is the likelihood that I need to run the heater hotter? My problem seems to be the hot end gets plugged up and near the top it cools off and jams.

4

Sounds like your filament is contaminated or oversize in places.

5

You need it cooler, not hotter. Whats likely happening is that the heat is creeping up the nozzle, or the motor is overheating. For the motor, lower the current to it. There are many instructions on how to set your stepper motor current. My favorite is to run the motor and adjust the trim pot while it is running all the way until it stalls. Then turn it up slowly until it runs again. Then turn it just a hair past that.

6

if PLA it’s way to hot, which could also cause it to jam as the heat creeps too far up the barrel of the hotend.

7

Some answers:

  1. I’m printing with PLA

  2. up until the last few minutes of the last print (where I had it cranked up to 210), I’ve been printing at 200C.

  3. I had already re-calibrated the extruder current and during prints 1 & 2 the motor was barely warm to the touch. I increased the current during the 3rd print after it jammed.

  4. This job takes about 1 hour to print. I had made 2 successfully with the large fan blowing at the gear side of the stepper before it jammed 1/2 way through the 3rd print. (and again 1/2 way through the 4th).

8

I got rid of this problem by decreasing tension on the roller bearing.

9

There is a certain point where increasing current to the motor will only make it hotter, not producing any more torque.
What is happening in your print is that the melt zone is moving too far upwards and softening the filament. 2 things can happen then, the plug solidifies up too high and gets stuck, or the filament buckles in the drive gear.
The fact that you can fix it by increasing the temperature tells me that the melt zone is likely moving upwards and when you increase the temperature you re-melt it allowing the plug to move.
A few things cause this. First is the nozzle is too hot. Heat travels up the nozzle to where the flament is soft above the normal melt zone. 2nd the extruder is too hot. As the machine runs, the extruder acts as a heatsink for the nozzle and the motor. This is amplified by an aluminum extruder as it has a high thermal conductivity. If you are running the motor at a higher current, it will make this happen sooner.
@Matthew_Satterlee is also correct on the idler tension. If it is too high, it can cause your motor to stall or need to apply excess forces.
More heat will not solve your problems, less heat will. A small fan blowing on the extruder will help cool down the motor and the cold side if the hotend. Lower the nozzle temperature. Lower the motor current.

10

So I’m trying out KISSlicer and downloaded someone’s config file. It has the extruder temp at 185 and so far its working. I’ve also printed a fan mount and have that running. Just started a 2 1/2 hour print…