Frustrating Extrusion Problem (Video)

Hello guys,

So I've actually had my Prusa Mendel up and running very smoothly for a while now but I've run into a snag that I cannot for the LIFE of me figure out.

The problem is with extruding. It will extrude the first layer or so PERFECTLY. No problems what so ever, and whenever I extrude manually or while not printing, I never run into any problems.

That being said, after a layer or so the extrusion sort of putters our and quickly, withing a few seconds, stops extruding altogether.

I've tried everything I can think of. I've adjusted the stepper drivers. I've taken the xcarriage apart and uncloggled the hotend with a drill bit. I tightened the springs on the piece that presses the filament into the gear.

I've included a brief video of the problem.

[www.youtube.com]


Nothing so far. I am getting very frustrated! haha. Any idea what the problem could be?

Thanks so much guys!

When you say "unclogged" do you mean that the filament gets jammed after a while.

i.e after its stopped extruding, if you loosen the springs, can you push the filament though by hand, or has become clogged so that its impossible to push though by hand.

From what you said about unclogging, it could be that your filament is getting jammed because of insufficient fan cooling of the transition area.

BTW. Are you using an All Metal hot end, or one with a PTFE tube liner. AFIK All Metal Hot ends need to be constantly cooled.

I am not using an all metal Hot End, is that a no brainer upgrade? I've really never had an issue up until this moment, but this problems a doozy.

In terms of clogging, I wasn't sure if the hotend was just getting stuffed so Unclogged it just in case. It was not actually an issue and did nothing to resolve the issue. I can push the filament through by hand AND, in fact, I can do this right after the print stops extruding.

I think the problem is that the filament is not getting grabbed by the gear, but those springs are tightened SOOO tight there is just no way that the gear is missing the filament

Just a thought, but have you checked that all the grub screws etc are tight in your extruder.

I had a similar problem and found that it case caused because one of the cogs was slipping. However mine was doing it on the 2nd layer when it started to print faster, not 1/2 way though the first layer.

But its worth checking

I am a newbie myself, but could this be a speed issue? If the head is traveling too fast for the extrusion.... Game over.

I don't think speed is likely to be an issue as its still printing the in-fill on the first layer, and all the in-fill should be printed at the same speed.
So if its managed to print the first half of the circle, it should be able to print the 2nd half OK.

You could try changing the speed in the slicer program, but it seems unlikely that its the issue.

BTW. What slicer are you using ?


But I'd definitely check all the grub screws etc, as a lot of faults are caused by simple mechanical issues.

Quote
rogerclark
Just a thought, but have you checked that all the grub screws etc are tight in your extruder.

I had a similar problem and found that it case caused because one of the cogs was slipping. However mine was doing it on the 2nd layer when it started to print faster, not 1/2 way though the first layer.

But its worth checking

That's exactly what's happening to mine! In the video it happened in the first layer but it was usually happening during the second layer when the print sped up. What do you meab by grub skrews and in what way were te cogs sloping? You mean the gears?

What exactly are grub skrews? I am using slic3r

Apart from my miss spelling of grub screws...

Definition of grub screw

Depending on your setup, grub screws are the small screws that are in the sides of the pulleys, that clamp the pulleys to the shafts of the motor.

e.g. The pulleys on the belt drive(s) will almost certainly have grub screws.

However if you have a wade extruder, which has plastic cogs. It uses a normal cap head hex bolt and a nut in the side of the cog, so its not strictly speaking a grub screw, (but serves the same purpose)

if it's a slipping extruder gear, you could try filing a flat on the extruder shaft, and turn the gear so that the grub screw hits the flat. Then that problem should be gone.

Oh I see what you mean by a grub skrew. But the problem is not a slipping gear. The gears actually work perfectly. The problem I think is that the gear inside the extruder by the hotend that grabs the filament suddenly stops being able to push the filament down. It's bizarre I really can't figure out why it is happening.

If the set screws on the gears are ok, and the bolt is not slipping relative to the large gear:

1) You clamp screws may not be tight enough. They need to be *very* tight. If you almost can't get the filament into the extruder that's about right with most springs. If you have some sort of uber spring, that may not be correct.
2) The current on your extruder motor may not be set right, you may be overheating the stepper driver.
3) You hobbled bolt may be junk
4) Your hot end may not be hot enough or holding temperature well
5) You may be trying to extrude (or retract) to fast
6) Your hot end may not be properly cooled

I've certainly seen all of those happen to mess up extrusion.

I got it working!!!

Thank you all so much.

Not even sure what I did haha, I just fiddled with everyone some more and now it prints. I THINK it was the motor overheating. Not sure though.

Thank you all so much, I really really appreciated all of the help!