Hi all,
I thought I'd share this experience with you all, in case anyone else is having a similar problem. I was printing the base, hinge and screen back on PC+PBT filament just like wermy, and everything was going great on my stock brass nozzle. However, I recently replaced that nozzle with a hardened steel one, because I've begun printing carbon fiber filament for other projects, which eats away at soft brass nozzles.
The carbon fiber was printing great, but all of a sudden all my PC+PBT prints were failing:
The first few layers were printing fine, but I'd eventually get the curling and poor layer adhesion that is associated with not printing hot enough. I was confused because I was already printing at the max nozzle temp for PC+PBT recommended by Push Plastic, 250C.
One of the knocks on hardened steel nozzles is that even though they can handle abrasive materials, they don't hold heat as well as brass. So I figured even 250C may not be hot enough. I tried again at 260C:
A finished print this time, but still pretty obvious curing and poor interlayer adhesion. I tried again at 270C:
Much better this time; still a little poor interlayer adhesion, but I think it would work good enough for the purposes of this piece. Then, I moved on to the base piece and tried at 272C:
Perfect! And look at that flexibility! So, the lesson I learned here is that for hardened steel nozzle 0.4mm, on my printer (Prusa i3 mk2, no enclosure), PC+PBT needs to be printed at a much higher nozzle temp than whats listed on the Push Plastic website, 272C. I have my bed at 106C, may increase to 110C. Hope this journey helps someone avoid my mistakes in the future!