I need to print some items that will go in my car, which sits in direct sun a good portion of the day and almost certainly exceeds 50 °C inside during the summer months (I've had PLA prints sag quite visibly under their own weight and sliding parts weld together, and PETG prints show slight warpage after a couple weeks in the car).

I have the ability now to print hotter than 250 °C, with Capricorn XS tubing installed in the heat break of my Ender 3. I'm examining nylon and TPU filaments for their higher temperature tolerance, but I don't see anything on any filament that clearly gives a glass transition temperature. Is it safe to assume this will be within the recommended bed temperature range, or is there another way to determine this (important, in my use case) value for a given filament?

  • 1
    $\begingroup$ Capricorn holds more than 250 °C? not according to them: captubes.com/safety.html Even the XS may hold but is not safe due to outgassing of the PTFE matrix. Ventilate well because some nasty stuff IS being released. $\endgroup$
    – FarO
    Commented Jul 30, 2021 at 22:26
  • $\begingroup$ Okay, every time I try A, someone says I need B, and when I switch to B, I get "no, you need A." Back to the all metal hot end? And have to swap back to PTFE lined when I want to print PLA again? $\endgroup$
    – Zeiss Ikon
    Commented Jul 31, 2021 at 1:30
  • $\begingroup$ TPU does not need temperatures above 250 to print. $\endgroup$ Commented Jul 31, 2021 at 21:43

2 Answers 2


The glass transition temperature is not always indicative of strength. Some polymers are solid well above that temperature, see https://omnexus.specialchem.com/polymer-properties/properties/glass-transition-temperature for all the polyethylene, for example.

What you need is the heat deflection temperature, which is very seldomly provided in the datasheets.

Luckily you can very roughly use the Tg for many polymers, but you should know that you are using a value which is only vaguely indicative of what you are looking for.


If there isn't a TDS on the manufacturer's website, you could email them and ask for it. If they won't give it to you, you could ask for the SDS to see if it has any additives. Polymaker has a TDS for every filament they make on their website, so I would recommend their filament for your purposes. I would also suggest you pay more attention to the heat deflection temperature, as it is probably more useful for functional parts.


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