• 0 Posts
  • 7 Comments
Joined 2 years ago
cake
Cake day: July 5th, 2023

help-circle

  • The latter half of this about aviation fuel went off the rails. Much of it is exaggerated or straight up inaccurate.

    First off, lead is used in fuel to protect non-hardened valves used in old engines. It is not just an octane booster, and it’s not some giant conspiracy that’s keeping it in use. Modern engines don’t need it, but people aren’t running it just to be dicks. It’s part of the engine design in really old stuff, which is a ton of old aircraft that haven’t been rebuilt and updated to use unleaded fuel. Converting and certifying these old engines for UL is prohibitively expensive for many hobbyist pilots, but on the whole, leaded avgas has been being phased out for years, and it’s becoming less common every day.

    Furthermore, airlines do not use leaded fuel because jet fuel does not contain lead. 100LL (100 octane low lead) avgas is used in small, older piston-engine aircraft, but that accounts for an incredibly tiny fraction of aviation fuel consumption, and there are unleaded avgas formulations available for modern piston engines that can use it. While leaded avgas does contribute to lead pollution, its effect is heavily concentrated around small airports with older private aircraft. Avgas is not a significant contributor to lead exposure for the average person.




  • Most nozzles and heat breaks have M6x1mm threads, so they’re pretty standard (double check yours specifically). Lightly chasing the heater block threads with a tap should clean out any gunk and ensure that your heatbreak and nozzle threads engage properly when you reassemble everything again, and that things get torqued together correctly.

    If your heatbreak tube and nozzle don’t have any ptfe liners or anything, using a propane/butane torch to cook the PLA to carbon and wire-brushing it off is a fast way to get those threads clean.

    If it’s all super gunked up, and you don’t wanna buy tools, you can generally buy just the heat break, heater block, and nozzle together pretty cheaply for most common hot end designs


  • Sort of. As the previous poster pointed out, you need to make sure it’s assembled in a way that the nozzle is seated against the heat break inside the heater block, not against the heater block itself. You’ll have to do a complete disassembly to clean it up properly, and you may need to run a tap through the heater block to clean the threads, but when you assemble it, make sure that you back the nozzle off a turn or so, assemble the hot end so that the heatbreak is bottomed out against the nozzle, then heat it all up and torque the nozzle up snugly to the heatbreak(quarter turn past touching is usually sufficient). There are YouTube vids that will demonstrate hotend assembly better than I can explain it, but solid nozzle to heatbreak seal is critical for preventing this


  • You have an incorrectly torqued connection between the heatbreak tube, nozzle, and heater block that is allowing filament to work its way past the threads and out the top/bottom. You’ll likely need to clean off what you can while hot in order to get it to a place where it can be disassembled and fully cleaned.

    You may need to heat or even torch some of those parts clean, since there’s no generally available solvent for PLA to soak it off.

    To prevent this, make sure you’re properly torquing those parts together according to the manufacturer’s instructions. Final torque is normally applied with the hotend empty and at temp.