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Hi guys,

Every now and then filament gets stuck in my cold end. This happens randomly, it could be in the beginning of a print, or like today - after 7 hours of printing.
a. I tried tightening the screw holding red handle but that didn't help.
b. I increased the flow rate to %110 and that seemed to help, but not solved the problem altogether.
c. The wheel feeding the filament is aligned properly with the filament.

I attached pictures. Any ideas?

Thanks!
Amir

This only happens if there's significant back pressure, what temperature are you extruding at? Too cold, and it may be the cause.

Jimustanguitar wrote:This only happens if there's significant back pressure, what temperature are you extruding at? Too cold, and it may be the cause.

This specifically is PLA printed at 210C with a .5 nozzle.
My first guess was that there is back pressure so I lowered the flow rate to %95 - still no good.

Try it at 220 or 230.

To know for sure what's going on, set the temp at 180, wait a second, feed the filament by hand, raise it 5 degrees... lather-rinse-repeat until you find the temperature that your particular filament flows the smoothest at.

210 should be perfect for PLA. When you loaded the firmware on the RAMBO did you reduce the motor current as directed in the manual on page: 238-239?

The current Automation Technology Stepper Motors, like the Kysan stepper motors require less current which will keep the motors running a bit cooler and prevent issues such as this.

Thank you all for commenting.
I want to update that this happened today again, when printing in ABS (228C) randomly and then stopped.

I did change the the current settings for the Kysan motors I'm using.
I am now testing printing PLA in lower temperatures and will update how that goes.

If anyone has any other ideas, please share!

You ought to doublecheck the alignment of the drive roller with the filament pathway. Maybe it's off center and not pushing the filament directly.

Hey guys,

I wanted to updated what seems to have fixed the problem for me.
It seems that simply removing the semi-transparent cover from the cold end allows the filament to stay cold enough to prevent it from smudging into the hole.

I left the cover off to allow me to fix it faster, then it stopped happening.

Did any of you print a fan duct for the cold end? Does anyone have a good design to share?

Thanks!

Good call on removing the cover - it's easier without it.

After an hour of printing check the temp of the hobbed gear. It should be warm to touch but NOT hot. I've seen a faulty stepper cause overheating on the hobbed gear and turned the filament soft before even getting into bowden tube. Replacing stepper fixed it right up!