Unresolved Extruder Stops Extruding Mid Print

I was getting some good prints, but now my extruder will stop flowing in the middle of a print. If I push down on the filament I can get it to start flowing again. The first time it stopped I killed the print, reheated the extruder and manually ran the filament (via Repetier), at first nothing but a few seconds filament started flowing again.

I've attached two photos, the first showing what it's like when it stops printing, it leaves hard little blobs. And the second showing how it's been stopping and then starting on it's own, which leaves those little half printed layers.

I printed one of the filament holders that mounts at the top so there isn't much resistance when pulling the filament, the extruder isn't getting cold, and the extruder gears turn normally so nothing obvious wrong with it. Any ideas?

 

We've all had this issue at some point. I'm assuming you're using PLA. Follow these steps.
- Season the hotend.
- Clean the hobbed bolt.
- Have your filament run through an oiler.
- Print at 210C and adjust from there.
- You may need to increase the spring tension on the extruder.
- You may need to reduce the retraction acceleration and retraction speed.

Happy printing.

 

Is your nozzle leaking out the top? Looks like you have an older brass heated block J-head with a gray PEEK body.

 

I didn't notice that. You don't need to season the J heads do you?

 

Thanks

Galaxius: Yes PLA, working on these suggestions. Is the oiler to clean or lubricate the filament?

It's been a while but if I remember correctly I did follow the instructions regarding seasoning the extruder.

Mike: It's hard to tell where it's coming from as it's covered in tape, and I'm not sure what version it is but I was thinking of replacing it with a E3D, are they worth it if just printing with PLA?

Thanks again.

 

The oiler both cleans and lubricates. It's essential for printing PLA in my opinion. Upgrading to an all metal hotend is a very worthwhile investment regardless of the material you're printing. Just do it lol.

 

for me, it was not disabling the driver restrictions in windows 8.1. Made that problem go away. Z axis/extruder stopping/skipping were that.

 

Okay thanks, I'll order one, this one is oozing a lot anyway.

btw I'm seeing Retraction Speed, but not Acceleration (looking in Slic3r-->Printer Settings-->Extruder), maybe I have and older version?

defendermd, do you mean not disabling the driver restrictions created the problem, so disabling them solved the problem? How do you do that? I have Windows 7. Thanks.

 

http://forums.robo3dprinter.com/ind...printer-connected-to-window-8-1-machine.1781/

 

I adjusted the acceleration value in the firmware, I think that's the only place you can do it.

 

These are the settings I found somewhere on the forum, you change them in the firmware.
Change:
Acceleration: from 3000 to 700
Acceleration Extruder: from 10,000 to 7,000
Acceleration Retract: from 3000 to 1000

 

Thanks, any simple instructions on how to modify firmware?

 

The way I've done it. Open the firmware in arduino... search for the setting you're looking for... change it. Compile/upload. Seems to work fine if you're just changing a value like that.

If you don't have a copy of the firmware.. that could be problematic.

 

Download and install the Arduino software. Download the firmware for your particular model Robo3D. Setup the Arduino software to connect to your printer (same com port and baud rate as your printing software). Open the firmware in the Arduino software, find and edit the necessary lines in configuration.h, compile and upload to the printer. Make sure your printing software is closed before you do the upload.

 

Thanks Galaxius, I might give that a go although prints are coming out pretty good after following your directions:
-cleaned the hobbed bolt (it looked pretty good)
-added an oiler (using olive oil)
-taped the captured nut that connects the hobbed bolt to the gear
-increased extruder heat to 200*
-reduced retraction speed

There is some very light stringing, more like tiny cobwebbing, which I'm not too worried about.

I'm still getting a build up of PLA on the bottom of the extruder so it's leaking somewhere. What causes this, and any cure or just switch to an extruder with a one piece internal tube?

Thanks.

 

Use canola oil instead of olive oil. Olive oil has a low smoke point.
Since you have a J Head hotend I strongly recommend upgrading to an all metal hotend like the hexagon or an E3D, you won't regret it and it will save you a lot of frustration. E3D are releasing some nice new designs.
Excessive stringing occurs when you're printing to hot and/or don't have adequate cooling.
Definitely get an all metal hotend and check out my low profile fan duct on Thingiverse.
http://www.thingiverse.com/thing:431160

 

Great thanks. I'm looking at getting the Prometheus, looks very nice.