Problems With Extrusion

[grahamsholt]

Up until recently I've been having great success with my M2. Lately I will get the printer up to temperature, extrude a little PLA and start the print. Very soon after the print starts, the flow stops and in order to get it to go again I have to manually push down on the filament. This happens even with I'm just using Simplify 3D to extrude some filament. I'll extrude a bit, it's fine, move across the room and try extruding a bit more and it just doesn't extrude. There's no stepper stutter and it doesn't appear to be stripping the filament, which as me baffled. Maybe there is a little stripping, but I haven't seen it like I've seen that on another machine that I've had.

I've tried a number of things including:
Extrusion temp (210 used to work, I've tried up to 225 with the same issues)
Making sure that the bed isn't too close to the nozzle
Idler bearing tension
Swapping out the hot end for a new one
Cleaning the hobbed gear

I'm running out of ideas and could use some help. As I have typed this, I'm thinking that maybe reducing the extruder temp will help just in case the filament is getting too soft.

Any thoughts are appreciated.

I've got a M2 Rev D.

[Jules]

If there's any stripping at all, the filament is deforming and it might be getting stuck going into the hole in the top of the hotend. (Tension is probably a bit too tight.)

Do a couple of tests using the information below and you should get it fixed. (205°-210° for PLA. You don't need to liquefy it.)

viewtopic.php?f=3&t=2694

[grahamsholt]

Thank you, that is an incredibly useful post. I'll work on setting the tension correctly this morning.

[grahamsholt]

Jules, you are amazing. It was indeed the tension. I'm down to 210 and it seems to be working well. I'll hunt for the answer a little harder next time.

[Jules]

Chuckle! You made it easy by listing all the things you had tried first.

That was all that was left.

[grahamsholt]

OK, I was still having a few problems with the extrusion, so I moved the temp way down to 195 and it works much better. I'm not sure if my new hot ends have the thermistor closer to where it needs to be, but it appears to be more accurate than the one that came with my Rev. D machine. I'm pretty sure the instructions said to run at +20 degrees, so that's what I've been doing.

Has anyone seen this change with the hot ends that have shipped out since January?

Thanks,
Graham

[Jules]

PLA prints well in the 185 - 220 range, depending on the manufacturer. if you're getting the best results at 195°, that's where to leave the temperature.

It's actually better to print at the lower end of the temperature range for PLA. You'll have less ooze, less warping, and it doesn't overcook the filament.

[grahamsholt]

As soon as I changed to a different color PLA, the problem came back. I had previously printed fine with this spool and now it extrudes for a bit and then gets stuck.

I just cleaned the extruder gear and I'm going to try again and see what happens. This is very frustrating as I need to be able to switch colors fairly often. This includes some 2 color prints.

The odd thing is that I didn't have a problem before I got the new hot ends. I had also notices that when I put the extruder together that the guide going into the hot end wasn't lining up due to an error when I put it together. That's been resolved, but it makes me think that I've done something wrong in putting it back together.

[grahamsholt]

I went back to my Rev. D user manual and it does say to run at 220. I changed my temp setting and ran a good looking 20mm calibration cube. I'm now trying to print a larger part of something. It's maybe 20 layers in and it's looking very nice.

Maybe it was a combination of things that I tried at 220 that didn't work, but now I've got good alignment on the filament path, good tension on the idler bearing and a temp of 220. I'll update when I run into more problems.

[Jules]

By all means, use the temp that works for that particular PLA. Some of them can take higher temps. (MakerGear can. It also prints very well at 210-215.)

Some of the other PLA's like it cooler, so just experiment a little. It's all part of the fun!