problem with extruder and PVA

Just for information how problem with extruder was strangely resolved (may be it can be useful to anybody).

(beginning of the story in [forums.reprap.org] )

After 3 jams Teflon barrel was damaged that extruder was not hold extruder screw, to fix a problem I have to create mettal scuffle to hold extruder on barrel and Teflon plumber tape for insulation/tention. When extruder started to print a calibration cube I released that exceeding filament pushed out of small holes over Teflon’s tape’s layers.

That difference allow to release pressure inside extruder and cube started to print OK (instead of jamming).

Or may be somebody has any suggestion what to do with extruder? or settings?

Wade extruder, calibrated (80,80, 2560, 491), filament speed set 15mm/min, PVA, 195 C, 85C bed, 0.36 (as it was specified ) nozzle.
With temperature high then 200 clear see the bobbles in filament (overheating).

And extruder jammed regularly (after it was assumed that was damaged beyond repair it starts to work!).

Can somebody recommended settings for a such configuration for PVA?

Can somebody correct me:
If melt flow index for ABS and PLA is 5 and PVA's melt flow index is 1.5, then for the same pressure PVA will be extruded 1.5/5 = 0.3 amount of regular PLA/ABS.

It mean that feed rate must be 0.3*30~40 mm/min = 9-12mm/min.
And profilemaker gives in that case for 0.36 diameter = 0.6 for flow rate. Is it true?

Actually number looks correct for my yesterday experiments – extruder leaked PVA via holes, and usage of a filament in testing was around this number = 70% went to printing and 30% was lost.
With the speed = 15mm/min and flow rate 1, mendel printed looks like with the speed 15 *.7 = 10.5mm/min.
Can somebody confirm that numbers?


After cleaning (again) extruder, it has deposits of overheating PVA which hard to clean. Looks like temperature instability in extruder 190+-10C has impact in this. For PVA will be beneficiary to has better controlling of a temperature.
Question: does somebody was able to configure temperature swing in Sprinter less then 5 degree? I tied to reduce from 500msec to 50msec interval for checking temperature – that give +-5C. Is it possible to get control better to 2~3C?

Just for information how the problem with extruder was strangely resolved (may be it can be useful to someone).

(beginning of the story in [forums.reprap.org] )

After 3 jams of the Teflon barrel, it was damaged so that extruder would not hold extruder screw, to fix the problem I had to create a metal scaffold to hold extruder barrel and used Teflon plumber tape for insulation/tension. When the extruder started to print a calibration cube, I realized that the excess filament pushed out of small holes over the Teflon’s tape layers.

The difference in pressure inside extruder and cube started to print OK (instead of jamming).

Or does anyone have any suggestions on what to do with the extruder? or settings?

Wade extruder, calibrated (80,80, 2560, 491), filament speed set 15mm/min, PVA, 195 C, 85C bed, 0.36 (as it was specified ) nozzle.
When temperature is set higher than 200, you can clearly see the bubles in the filament (overheating).

And extruder jammed regularly (after it was assumed that was damaged beyond repair it starts to work!).

Can somebody recommended settings for a such configuration for PVA?

Can somebody correct me:
If melt flow index for ABS and PLA is 5 and PVA's melt flow index is 1.5, then for the same pressure PVA will be extruded 1.5/5 = 0.3 amount of regular PLA/ABS.

It mean that feed rate must be 0.3*30~40 mm/min = 9-12mm/min.
And profilemaker gives in that case for 0.36 diameter = 0.6 for flow rate. Is it true?

Actually, the numbers look correct from my experiments yesterday – extruder leaked PVA via holes, and usage of a filament in testing was around this number = 70% went to printing and 30% was lost.
With the speed = 15mm/min and flow rate 1, mendel printed looks like with the speed 15 *.7 = 10.5mm/min.
Can somebody confirm that numbers?


After cleaning the extruder again, it had deposits of overheated PVA which was hard to clean. Looks like temperature instability in extruder 190+-10C has an impact. For PVA it will be beneficial to have better controlling of temperature.
Question: was anyone able to configure the temperature Sprinter so that it swings less then 5 degree? I tied to reduce from 500msec to 50msec interval for checking temperature – that give +-5C. Is it possible to get control better to 2~3C?

just cleaned up your grammar and made it a bit easier to read.