As a long term Bambu PET-CF user; I will encourage users to experiment with it as it is a phenomenal intro to working with more demanding materials, I have found it easy to print compared to most other, higher end filament, with great overhang and layer adhesion. The material properties are great compared to accessible, non-filled filaments. With having access to a filament dryer and encoded printer; believe it is a great filament to commit to when wanting to upgrade from “intro” filaments.
With your question of regretting PET-CF for specific prints; I can’t say it differs much from my current PAHT-CF prints in any individual metrics that is worth noting. It is not stiff enough to be brittle, it is not flexible enough to not hold dimensional accuracy, nor is it lacking in a quality that I easily achieve in competing materials. Its strength or structure doesn’t (noticeably) warp to oil or grease; and has phenomenal temp resistance and low temp conductivity.
Despite being an engineering filament; it is a lower end material within an engineering spectrum. Its dependability and reliability come at a cost of a lower ceiling for performance. In discussions of higher end-consumer grade filament, PAHT-CF, PPA-CF, PPS-CF, other PA612 blends; in my opinion, outclass PET-CF when cf filled nylons are printed in ideal conditions.
But for the price, easily achievable print quality, lack of demand for a heated chamber and lower demands in pre- and post- processing compared to nylons that need extensive drying and annealing to see ideal results; PET-CF is a great high end compromise for a demanding project like the FGC.
I think that PET-CF is a great material and should be considered when projects leave the prototyping demands, but are still within realistic consumer expectations. I printed some great lowers with PET-CF on my ender 3v2- DD19.3, sigxty nine p226, Orca, and an SL-9; but now am playing with more demanding materials on my X2D and reprinting some projects with nylons due to wanting to address finish blemishes and low layer adhesion due to my old printer; and wanting to achieve a higher quality not in reach with my previous printer.
Regardless of direction you go, when using a Bambu printer, using Bambu filament and using their recommended quality settings profile for the filament you are running almost fully skips the calibration and torture tests that used to be customary for engineering filaments. I personally like to reduce max speeds, flow rates and increase temp but that’s a personal preference.
Tl;dr
I would recommend PET-CF as an intro to high end filaments due to its easy of use, but ultimately would suggest trying cf-nylons if you are comfortable with committing to both a higher price point, and a more demanding pre- and post processing commitment.
I have done most of my printing in PET-CF, and while I have been happy with results; I see high performance PA612 blends having a more desirable outcome in ideal conditions.
