I've machined multiple hot end heater blocks with varying success as far as leaks (between my PTFE tubing and brass heater block), but the most recent and most carefully done has just started leaking and I'm out of ideas as far as making a thread work. I've tried using stupid amounts of teflon tape around it too but it always ends up leaking after a certain amount of time. Even tried JB welding the tube in place with some success (still failed eventually) and other thread sealers such as Loctite but they dont seem to grip the teflon at all.

My nozzle has never leaked once though, interestingly enough (brass on brass w/ teflon tape)

considering trying to retrofit a professionally made plumbing connector as a solution but dont know whether that will help as far as the teflon tube goes.

Anyone have any suggestions or creative ideas on this? Or just having the same issue and want to commiserate/brainstorm