I saw an extruder mod on Amazon "EAONE 2 Pcs PTFE Teflon Tube (2 Meters) with 4 Pcs PC4-M6 Fittings for 3D Printer 1.75mm Filament (2.0mm ID/4.0mm OD)" Anybody know how this is fitted? Is it simply tapping the feed hole on the top?
Is this what you are referring to?
If yes, the cold end of the extruder is nomally already tapped and you simply have to screw the new fitting in it. The PTFE tube itself needs just to be fed through the hole in the fitting until it cannot go any further.
Failing to do so will most likely result in a clog and/or leaking.
It is a self-locking mechanism, in order to release the tube you have to press down the plastic flange on top of the fitting while pulling up the PTFE tube.
that item is for a bowden setup. (the a8 does not come with a bowden setup, but can be modded to have one.) when installing the bowden setup on a a8, the first thing you will need to do is move the motor to somewhere else, there are tons of choices on thingiverse. then the PC4-M6 fitting will screw into the black aluminum piece that the throat used to screw into. and the other end will go into a customised hot end. again tons of choices
now this is oversimplified, because installing a bowden extruder on a anet a8 is a lot more complicated than explained above due to the sheer number of options. just search anet a8 bowden and you will have lots of choices.
but it works as mac said, the PTFE tube slides into self locking fittings, the PC4-M6. to release simply push the top of the fitting down and pull out the tube.
source, my own anet a8 modded to have a bowden setup.