Grinding PVA

There could be several reasons for grinding material (as described here), but specifically for PVA incorrect handling or storage of the material can lead to grinding. PVA should be printed and stored at a low humidity to avoid problems while printing. We advise a humidity below 50% for storage and below 55% while printing. It is also recommended to keep the environmental temperature below 28 °C while printing. In a standard air conditioned office room this humidity and temperature should be easy to reach.

When PVA is ground down by the feeder, there are three main causes:

Incorrect storage

PVA is a material that absorbs moisture relatively easily and therefore storing it correctly (resealable bag, humidity below 50%) is important. If PVA absorbs too much moisture it will get soft and malleable/pliable and in some cases even sticky. This can cause problems in the feeder as it might not be able to forward the PVA properly anymore.

Coated Bowden tube

The Bowden tube can get coated on the inside due to incorrect printing conditions (mainly a too high humidity). If the humidity of the printing environment is too high (above 55%) and temperature is too high (above 28 °C) PVA might not be able to move easily through the Bowden tube. A solution for this is to clean the Bowden tube and dry it very well.

Clogged print core

Due to a too high humidity PVA can lose quality over time and lead to clogs in the print core. As a consequence filament might not be forwarded anymore, causing grinding in the feeder. When this happens, the print core should be cleaned by following the procedure described here.