Underextrusion with Extrudr Green-TEC

[conny_g 251]

Hi all,
 

I am confused about print temperature.

Was using Extrudr Green-Tec for a few things now and it is said to be printed 190-230 C.

I was never able to print reasonably below 220 degrees (at speeds of 40mm/s) and now with my latest object with a print speed of 30-50mm/s I even needed 270 degrees to avoid underextrusion.
I wonder what the problem might be.
Don't think I have a clogged nozzle or a defect extruder heater as other materials behave ok, I can print regular PLA with 210 degrees.

 

Or does the Green-TEC simply need high temperature?

Cheers,
Conny

[geert_2 557]

I don't know Green-Tec, so I can't comment on that.

 

But have you tried to remove the bowden tube at the nozzle, and then feed the filament manually, while adjusting the temp in steps of 5°C? This might give you a better feel of how it behaves, and at which point it starts to flow well.

 

Of course, a few atomic pulls might also help. It could be that the nozzle isn't blocked, but the opening is a bit reduced, or that the internal walls are covered by burned residu, which hinders heat transfer? You could try my more gently atomic pull method: remove bowden tube, manually heat the nozzle to the normal printing temp, push through a bit of filament, then dial down temp to zero, let filament cool down to room temp, and then gently wiggle and turn the filament. No brutal pulling. Then heat the nozzle up again to 70°C (for standard PLA, other materials require different temps, use trial and error), and while it is heating up, gently turn the filament until it comes out. Always gently, no brutal force, so you don't risk bending the rods or displacing the nozzle parts. The long manual with pictures is here (scroll a bit down): https://www.uantwerpen.be/nl/personeel/geert-keteleer/manuals/

[conny_g 251]

That makes sense, will try that!

[conny_g 251]

When reading more about the atomic pull I noticed that sometimes also a worn-out Teflon coupler could be the reason for underextrusion. But as the problem is going away with temperature I would rather assume a clogged nozzle as higher temperature does not help for the Teflon coupler issue (the filament gets molten below the coupler), but it does for a partly clogged nozzle.

[yellowshark 153]

Whilst it is not PLA its temp. range is very similar. So if you had to print at 270, which is way to hot for PLA I would not be surprised if you some burnt green-tec in your nozzle.

 

Another thing to check is your filament width. The top rated suppliers quote a diameter of 2.85mm +/- 0.05mm. Once you hit a width of 3.00mm you will get problems with friction/sticking in the Bowden tube. Really you need a digital calliper calibrated to display two decimals of a mm. Take your calliper along say two or three meters of your filament about to be fed into the Bowden tube and randomly and carefully check the diameter of your filament. If you consistently hit 2.85 +/- 0.05 the you should be OK but if you get any larger variations then check a longer length with a greater density of checks for better verification.

[conny_g 251]

2 hours ago, yellowshark said:

Whilst it is not PLA its temp. range is very similar. So if you had to print at 270, which is way to hot for PLA I would not be surprised if you some burnt green-tec in your nozzle.

 

Of course I am not printing it always at 270, I ended up increasing to that temp to end the underextrusion and started to worry what would be wrong.

 

2 hours ago, yellowshark said:

Another thing to check is your filament width. The top rated suppliers quote a diameter of 2.85mm +/- 0.05mm. Once you hit a width of 3.00mm you will get problems with friction/sticking in the Bowden tube. Really you need a digital calliper calibrated to display two decimals of a mm. Take your calliper along say two or three meters of your filament about to be fed into the Bowden tube and randomly and carefully check the diameter of your filament. If you consistently hit 2.85 +/- 0.05 the you should be OK but if you get any larger variations then check a longer length with a greater density of checks for better verification.

 

Will check that.

 

Was doing a few cold pulls before and disassembled the head to check the coupler. And there was some scratchy edge at the lower inner end that I carefully removed with a scalpell. After that a piece of filament moved much better through the coupler than before.
Then started reprinting of the last item and it looked much better even with just 235 C. Let's see what happens as it progresses.

[conny_g 251]

Much better now, that was it.

[conny_g 251]

The other printer had a worn Teflon coupler and some burnt crap in the steel isolator....

[fergazz 60]

Nice! A need to change my teflon couper cause I'm getting much more underextrusion nowadays :/

 

Just for comparision I set my  natural color PLATec filament from Biofila, that are very similar with GreenTec from Extrudr, with a bit more temperature comparing to colorfabb pla/pha. I add just 2 degrees and it works pretty good!

 

Make sure to double check diameter of GreenTec cause someone in PLATec topic says that found incosistency diameter in that GreenTec filament.

Edited February 2, 2018 by fergazz

[fergazz 60]

it was @nilrog

he said: 

"The only thing I have noticed with greentec is that the filament diameter on the spools I got is not so consistent and on at least one spool it exceeded the tolerance they stated. It is not as consistent as the ColorFabb filaments I have.

But it still prints great"

[conny_g 251]

I have changed my coupler and since then it's better, but still the Green-Tec has a slight tendency to underextrusion. I need to increase the flow slightly to 105% to get nice results.