standard hotend upgrade

#1
ok so I print a lot of protopasta carbon fiber pla. I printed through 6 kg in the past 3 weeks on a customers project. obviously I needed hardened nozzles, but have been burning through the 2 hotends on the dual extruder (we do not really ever do any dual extrusion prints). I was about to order an e3d, but got to looking at the standard hotend. I have a couple hardened nozzles that I purchased from proto plant before I realized that you couldn't swap the tip on the gmax standard hotend. so the left hotend had served me well and lasted many kg of what ever I could push through it. I didn't get a pic but when I pulled it you could put a thin paperclip in the .4mm opening lol. I have decided to give it a second chance

here is what I did. I forgot to take some step pics but i'll show you what I got and explain the rest.
THIS MOD IS NOT FOR EVERYONE!!!!! I HAVE CNC MILLS AND LATHES AT MY DISPOSAL , BUT THIS COULD BE DONE WITH SIMPLER TOOLS.

ok first disassembled the hotend. the plastic heatsink will easially separate with a vice and 13mm wrench.
then I ran a drill through the entire brass piece just to clean it all out.

then I placed the hotend in the lathe and turned the tip flat. I was going to get rid of the tip all together and face it all the way to the square block but after measuring everything I decided to stop once I got enough flat to mill it and thread it.

After that I put it into the mill and this is where I got lucky with the face I did on the lathe. there was enough of the round part to touch off center. I did a quick program with a 1/8" flat endmill and milled a 5mm diameter hole to a depth of .318". then by hand tapped it to m6x1.0.

when I tapped the threads it did break through into the area that the heater goes. once I got the nozzle in I had to run a drill through the heater hole to allow the heater to clear. So at this point I am not sure if I have a reusable hotend or if I just extended the life of it one time for $15 and 30 mins of my life playing.

Ill post more as I get results. I am printing a single extruder to swap everything over. I did notice that it is slightly longer with the screw in nozzle so the touch bl will need adjusting