In a previous blog I described a possible method to recover PLA that has become unusable due to the moisture it has absorbed from the air.
My hypothesis was thus: By putting stale PLA inside a vacuum clothing bag and drawing a vacuum, I could speed up the drying process.
When I posted the original article, I received some great feedback from the public. Many of the comments said to put the stale filament in an airtight bucket or box with lots of silica desiccant, then wait 2-3 weeks. This is certainly a viable method, but I wanted to develop a filament recovery process that would work in a week or less.
I knew laboratories used commercial heated vacuum chamber for pharmaceutical research. I wanted something that would work closer to room temperature and come in at a reasonable budget when I developed my procedure.
As I use the vacuum bag daily, I noticed it was not perfectly airtight. Without a vacuum pump attached to it, I could not maintain a constant vacuum. In the future I might double vacuum bag the entire filament, or invest in a better airtight box. On a more industrial scale I would invest in a commercial vacuum pump and heated chamber.
Someone also posted on my Facebook page that such chambers are used to extract hash oil and other cannabis products. Those that live in a states where cannabis is legal may have access to heated vacuum chambers designed for cannabis products.
They range in size from 1 – 5 gallons, which is big enough to dry out whole spools of filament. Commercial 3D printers may consider buying or making a heated vacuum chamber to quickly recover stale PLA.
DISCLAIMER: Always check your local laws and regulations to see if owning and operating such equipment is legal. 3D-PT is aware that heated vacuum chambers can be made with household items. All vacuum chambers pose the risk of implosion, so assemble and use at your own risk.
I ended up leaving the PLA inside the vacuum bag for 13 days due to a hectic schedule that kept me away from my 3D printer. I had originally planed on testing after 7 days.
The first spool it tested on was some pink 1.75 mm filament from Prototype Supply. Before I dried it out, it was bubbling, giving off a lot of steam and gave me a lot of feed issues when I tried to print it.
Now as I print some gyro fidgets I am seeing none of these problems. The filament feeds smoothly through the hot end with no bubbling, crackling or steam. It has printed smoothly with no warping or other issues. Coming off the spool, the filament does seem to stick a bit to itself, which may be a concern on long prints.
The next filament I tested is MakerBot 1.75 PLA. This is the most expensive filament in my inventory at $0.57 a gram. When it too started to give off steam and cause jams, I wanted desperately to keep it in stock.
For the same gyro print it too came out as a smooth print. Even better there is none of the warpage that MakerBot filament is prone to.
Overall I think using a vacuum to dry PLA is a viable method, no matter if you use a commercial vacuum chamber or storage bag. If you have multiple spools of PLA to store, keeping them inside a vacuum bag with a desiccant may be the way to go.
Vacuum drying PLA is a viable and hassle – free way to recover stale PLA for use.