New RepRapPro Hot End - 3mm mod?

RepRapPro announced their new hot end a few days ago, replacing the brass nozzle with a one-piece stainless steel part. There is still a PTFE piece inside to accommodate 1.75mm filament, but I have been wondering whether it would be possible to modify this hot end for 3mm? As far as I can see, the OD of the PTFE liner is 3mm, leaving a little bit of room to the walls of the barrel.
So has anyone tried just removing the liner and using the hot end (or one of the predecessors) as an all-metal one? Also, do you happen to know where I can find the drawings of the parts? I have checked their github repo, and the wiki, but could not find anything - and I cannot imagine it being closed source.



Edited 1 time(s). Last edit at 05/19/2013 05:16PM by uGen.

A pdf of the one-piece nozzle design is here: [github.com]

You'll probably see that there is a step in it, so you'd probably want to drill it out to the end at 3mm - it wouldn't work as-is. Also, the ptfe is there to reduce friction, and keep the melt zone very focused on the tip, and consistent. Without it, you would probably need to polish the the bore of the nozzle, like Prusa's new hot end. Then you would need to come up with some way to hold the nozzle in the existing heatsink block (the fan and heatsink take heat away from the top of the nozzle), and/or come up with a way to connect a 3mm internal diameter Bowden cable, or fit it to an existing 3mm extruder.

Not impossible, just needs consideration.

One more thing to add to the already good reply of droftarts, filament isn't always exactly 3mm, so making it exactly 3mm's will probably cause jams a lot. Unless you have 100% absolutely insurance that the filament you're using is consistent in diameter. My filaments usually go from 2.92 to 3.07 and I've had extreme cases of 3.25 to 3.50 in older filaments I used, but I think that was a freak accident. I threw away that inconsistent batch.

Thank you both. Guess it isn't worth modifying this hot end then; for the work invested, I could as well machine a completely new one. Just thought that if the internal design was already suitable, one could just modify it a little bit.

@Ohmarinus: That is exactly the reason why I wanted a look at the drawings. Turns out that the internal diameter is 3+/-0.1mm. Most of the 3mm hot ends I have seen seem to be more like 3.2mm internally.