PHA shrinks a bit when cooling. But the first layer cannot shrink, being glued to the plate. This makes the printed model eventually warp and even detach from the plate. When I tried to use glue, not only the model was still warped, but it eventually made the PEI plate pop off the magnetic bed.
An obvious solution is to print the model entirely over an elastic support, so that it acts as a buffer joining the non-shrunk 1st layer and the slightly horizontally shrunk model. PHA is elastic, so it would do as the support material.
The problem is, the only currently available method of assuring that even the bottom of the model is printed over a support high enough is making the raft height non-zero. However, rafts aren’t elastic enough and larger models still warp and detach.
To work around that, I have chosen “organic trees” which are sufficiently elastic, and to increase the height of these trees, as opposed to adding rafts below them, I added to the model’s STL a small cube, placed 15 mm beneath the model’s bottom (it can be seen in the middle of the photo).
It raised the model and produced a tall, elastic tree support, finally allowing to print nice PHA models. The model in the screenshot was printed at 210 deg C and maximum filament flow 10 mm3/sec.
