Under extruding help

[GuardsmanBlue]

I'm having some under extruding issues that I can't figure out. I'm hoping it's something simple that I'm missing. I've been printing for the last year and a half with very few issues. About a week ago the printer started under extruding. When a print starts it lays down about 5mm of nice thick line and then it thins to almost nothing. Occasionally it'll print what looks like a beaded necklace, evenly spaced little blobs with a very thing string connecting them.

This happened at around the same time I upgraded to Windows 10, but I think that's just a coincidence. I use Simplify 3d to create the gcode, upload it to octoprint and kick off the print from there. I've tried uploading previously good gcode to octoprint and printing but get the same issue, taking Windows 10 out of the equation.

I removed the nozzle, heated it with a torch and ran guitar string through it, then ran cleaner filament through it and still have the same issue. If I extrude into the air it seems to extrude fine, the extruded plastic measures 0.45mm which I think is where it should be. I can speed it up and it appears to keep up just fine. I'm printing with PETG with the settings from this forum. My target temp is 247C, but if I check the temp of the insulation around the heater block it's showing about 160C, is that right?

I've also tried connecting my laptop directly to the printer and printing from S3d. No difference. While printing I tried turning the extrusion override dial up to 150% and there was no difference. I've tried PETG and ABS, no difference.

Any suggestions on things to try? I'm running out of hair to pull out.
Thanks
Tom

[TheMaker]

Hey,

Just a thought, how tight is your tension on the filament? I know my adjustment for the tension worked its way loose and that caused the printer to have a similar problem with under extruding filament.

Let me know if this is the case.

[GuardsmanBlue]

I've tried tighter, I've tried looser, didn't seem to make much of a difference. I also took it apart and cleaned out the drive gear thinking it may be clogged allowing it to slip. I'll pay with the tension some more and see if it helps.

[Jules]

Playing with the tension is a very hit-or-miss proposition.....try this instead:

viewtopic.php?f=3&t=2694

[GuardsmanBlue]

Thanks Jules, I should've known you'd have a great write up for that! I'll check it tomorrow and see what my bite marks look like and adjust accordingly.

[GuardsmanBlue]

The tension on the filament looks good. I'm thinking my nozzle may still be clogged. I ran another 300mm of cleaner through it and it's a little better. It's laying down a consistent line, but parallel lines aren't touching. It still seems like it's not extruding enough. I've checked the filament going in and its a consistent 1.74mm which is what I have s3d set to. I ordered a spare nozzle. Any other suggestions?

[Jules]

Give the spare nozzle a try. The problem with a partial clog is you might not see it, it might just be coating the insides of the nozzle, although torching it should have taken care of that. (Who knows?)

How fast are you printing the PETG? ABS can go quickly but PETG is pretty flexible and has to be printed at a turtle's pace.

[GuardsmanBlue]

I was able to get 3 prints to finish today, I'm not thrilled with how they turned out, the first layer seems under extruded and the rest seem over extruded. I think all of my messing around to get more extrusion on the first layer over corrected on the rest of the print. It sounds like a z-axis offset issue, like there is too much gap on the first layer. I've calibrated multiple times and if anything it's a little too tight. I'm sure it's level, but I may try messing with the z-axis offset to see if I can get it any better.

I used a propane torch to heat the nozzle, it may not have gotten hot enough. That was my first time using a torch to clean a nozzle. I have an oxy acetylene torch but I was afraid that would get it too hot. I will try the new nozzle and when I switch them I'll try cleaning it again.

I'm running the PETG at 3200mm/min (53mm/sec).

[Jules]

That's a good speed for PETG.

[GuardsmanBlue]

I was able to play with it a bit more last night and it was my z offset. I think the initial issue was a clogged nozzle. I leveled the bed when I first started having issues, forgot that I had a z-offset set (I've only messed with the z-offset once so it's not something I normally check). I figured it was something simple I was missing. Thanks again for the help