AVOID High Temp Printing in Enclosures
I managed to overheat my XL and warp every loaded printed part in it.
Let me explain.
I print in HIPS. It is my go-to filament for wonderful mechanical properties and the fact it can be smoothed with Lemonine. However this throws off Styrene vapors. So, being tired of the hall bathroom being the Printer Fume Hood Room, I found a third party creality enclosure that fit it, a ducted fan, and a carbon filter. I needed a part for mounting the filter, aluminum AC tape was not enough. So I zip up the Mylar coated enclosure to keep the fumes in, and set it to making a bracket. It printed for about a centimeter and stopped extruding, I found this a few hours later. Odd. I tried to reprint it, and the XL could not find its home, and was crashing in scary ways, everywhere. Took me a while, but I realized that I print HIPS HOT AND FAST, 265, 110. The enclosure had retained so much heat, that the belt and filament tensioners had warped from the heat.
I am a little embarrassed this took me three days to figure out. I was able to heat and re-bend the filament latch, and I was finally extruding again. The belt tensioners still had enough play to get the belts back to normal range. I am printing some carbon fiber PETG parts on my MK3.6S+ (Oh gods it is a Frankenstein's monster of mismatched upgrades and firmware), and hopefully they won't need to be replaced ever again. Printing cold now. I am throwing all types of logic at that fan controller, and heat will now be a factor too, including emergency power scram to the printer.
Tl;dr, If you get your enclosure too hot (over 80°C), you will melt your XL.
RE: AVOID High Temp Printing in Enclosures
Funny I was about to post the same thing...but I have a "normal" enclosure made with acrylic. The temp during an ABS print was about where yours was, 260. I found that after one or two prints the filament stopped extruding properly. I finally realized it was the idler arm not pressing against the nextruder drive wheel. I've since reprinted them in PC, but haven't had a chance to replace them yet. The strange thing is only the two extruders that I was using with the high temps had this issue, the others were still fine...Its easy to feel the tension when you undo the lock. The warped ones were super loose and pretty much just dropped. These really should have been made with machined aluminium.