Over the past four years, I have reviewed/used over 20 3D printers from various manufacturers. I recently reviewed an M5 supplied to me by AnkerMake at no cost for the review. Many users complain of hot end jams and other extrusion issues that I think may have a common cause.
The hot end of many machines, including direct extruders, utilize a PTFE sleeve, limiting practical operational temperatures to about 230C +/-. This is fine for PLA, PLA+, and TPU but is at the low end for PETG. People running into issues may be attempting to print at temperatures too hot for there machine which damages the PTFE sleeve.
In addition printing at temperatures above approximately 230c with a standard PTFE based Bowden tube or direct extruder liner is potentially unhealthy as PTFE improperly manufactured can produce fumes you should not breath at high temperatures.
The advantage of hot ends using PTFE sleeves is the prints generally string less, which is a significant advantage. For example, I have an Ender 3 S1 and an Ender 3 S1 Plus. The S1 Plus has an excellent all-metal hot end but strings significantly when printing. So depending on my model requirements, I use the S1 or the S1 Plus.
To print at higher temperatures, replace in PTFE sleeve or Bowden tube supplied with the printer with Capricorn XS tubing. For sleeve just cut a full size Capricorn XS tube down to size.
Here is what Capricorn says about their XS tubing:
“Our XS Series tubing has additives that will allow it to print at higher temperatures without deforming, but safety is still a concern due to PTFE offgassing.”
The bottom line when printing above 220c or 230c always use good ventilation.
Here is a link to what Capricorn says about safety and the temperatures their tubing can operate at:
You can purchase Capricorn XS Tubing here: https://www.amazon.com/gp/product/B07PS3NH82