I have some PET-CF from Bambu that I need to use for it’s temperature resistance. I need parts that can withstand temperatures inside a pressure cooker, and so I bought PET-CF without realizing that it seems to need annealing to actually reach the stated HDT.
So, because I don’t have the money to drop on a dedicated oven for it, and I still need to be able to use any of the cooking ovens I have in my house, I was wondering if anyone has tried just annealing prints directly on the bed of their printer? I figure this would work because the TDS for PET-CF states that Bambu dried and annealed all specimens at 80C for 12 hours prior to testing, and since we dry the filament on the bed at 80C, this should be hot enough to anneal as well. I also have a P1S, if that makes a difference here.
I’m mainly just trying to see if there’s a way to anneal PET-CF parts before I drop money on a roll of something that can withstand the temps I need directly off the printer.
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So, I decided to just try printing something to give it a go and see if it’s even really possible to reach those temps, and my “experiment” is still ongoing but as of right now it looks promising.
In order to make sure there would even be close to proper temperatures, I put a filament box on the bed over the part, with a hole cut out that I put one of those cheap round thermometer/hygrometers in.
That setup with only the box reached a maximum of about 65C. I then covered the box with tinfoil, 1 layer inside 2 on the outside and tried again. This time, I discovered that those thermometers max out at 70C.
I decided to then place another one of those cheap ones inside to see if I got any different results, and sure enough, when I checked back a half hour later it had stopped displaying anything properly and the screen had small spots from temporary heat damage.
I wanted to find out the actual air temperature inside as best I could, and since I don’t have any proper thermocouples or anything, I janked together something using an old E3 board and some hotend thermistors. Right now they’re reading 90C with the glass bead thermistor, and 85C with the metal barrel type thermistor, and they’ve only been in there about 10 minutes.
So obviously it’s not exactly a proper annealing oven, and I doubt there’s any kind of even heating inside that box, but this at least shows that it’s possible to get internal air temperatures sufficient for annealing within the printer itself. I plan to also try putting some small fans to circulate air within it as well, and of course actually test whether or not this annealing anything.
Also, if anyone sees this and thinks “somebody’s tried that before and it didn’t work” please tell me where, I looked everywhere online I could think and couldn’t find anything but unanswered questions from others wondering the same thing 
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It has been over a year since your post and no one has built on your idea.
I think it’s a great idea. Did you have any luck with annealing parts on the print bed?
I’m wanting to do the same but on a heat pad. I use it to dry filament with the box just like you, and it works great for that.
Hopefully you had good results.
Thanks for your time,
Happy printin.
Life and school got in the way so I was never able to fully test the idea, but around the start of the year I got an x1 and decided to try again. I don’t have the ability to really properly test whether the annealing actually worked, but the one “test” I tried with temperature resistance showed promising results.
I had originally wanted to use the annealed properties to create parts I could use within a pressure cooker which I know can get up to the 120-150C range. I did create those parts and anneal them using this method, and ran them through a full cycle (>1hour) in the pressure cooker. The parts never seemed to deform even after that much time, so at the very least their temperature resistance was somewhat improved.
I’m glad to see others interested in using this method to anneal parts! I think it would be awesome if more people could try it, since that would allow many more people to get the benefits from high strength filaments without having to ruin their ovens or shell out hundreds of dollars for specific annealing ovens. I hope you’re able to get good results as well!
