Yesterday, I wrote about the bad consequences of letting printed PLA get too warm – in summary, it softens and bends. In the case of my 3D printer, it resulted in the print head getting out of alignment. Thinking it over, it occurred to me that I might be able to fix the problem by reheating the plastic a bit and straightening it out. To my surprise, it worked. I boiled some water, put it in a bowl and immersed the distorted component. After a few seconds I pulled it out and flattened the distorted area. Easy. It worked for both of the components I blogged about yesterday.
A little more experimenting shows that the water temperature can be a lot less than boiling (cool enough to dip hands in, which is convenient) and still soften PLA quite effectively, giving it a few seconds of pliability before it cools to stiffness again. Even more interesting is the shape memory effect that I really wasn’t expecting. Before I played with the critical parts, I took a simple printed bar of PLA, and dunked it in hot water. While it was flexible, I bent it into a circle, and let it cool. Then I dropped it back in the hot water. It uncurled itself and resumed its original shape. I’ve since done this with more complex parts, even screwing one into a ball. I’ve put a video of this on YouTube.
It’s an entertaining but probably completely useless phenomenon.