@Sanjay_Mortimer @Tim_Rastall here it is our dual (for the moment only one active) extruder 
Originally shared by BD BadDevices
http://baddevices.wordpress.com/2013/08/05/printing-experience-with-new-all-metal-hot-ends-2/
That is awesome Stefano - you must be very pleased. Your clamping approach looks very similar to mine, especially the way the Bowden press fit connectors are mounted on the top plate - is the plate tapped or do you have a retaining nut for the fitting underneath? I am totally using your fan mount if you stick it on Thingiverse 
Thank you very much Tim, the top plate is tapped and also if the alluminum are quite thin there is no too much force exerted on the press fit so it is good. I uploaded this morning the fan mount; i had doublechecked all the dimension, but in case you have problem or suggestion give me advice 
Looks good! I assume the ridges you’ve put on the inside to prevent the mount from moving up and down the heatsink? My E3D provided mount is a little melted because of that Thanks for posting the inventor file too!
I have just started to put together a dual nozzle head for the Ultimaker. Have you measured the temperature close to the top of the aluminium part? Thanks.
@Tim_Rastall Yes, I copy the philosopy of the orginal mount that have some round ridges; I make them a little more sharp, but hope not to be too tight with tolerances to mount onto the heads. @Paulo_Geraldes I do not measure it, but I’m able to take the head in my hand from the groove mount part also with the hot end at 300 degrees; the E3D guys had made an amazing job to maintain the cold end really cold… I have not so much experience with different hotends, but the last I use is a J-Head and the Peek part become quite hot during printing while this is almost ambient temperature.
@Stefano_Pavanello that is probably under 50deg C that is kind of what I was hoping. Great, thanks.
Keep up the good work. I will be posting some of my stuff later.
@Paulo_Geraldes
As long as you aren’t in a heated chamber or something weird, the top of the E3Dv5 isn’t going to get anywhere near 50C. Just ensure everything is setup properly with regards to the cooling fan and you’re golden.
@Sanjay_Mortimer in normal open air operation (no heated chamber) what would you say the top of the E3Dv5 temp is in your experience and how did you verify this?
@Paulo_Geraldes
I once took the earlier v4 hotends, which had less effective cooling. Put a heater cartridge in it, no thermistor. Hooked up the fan and heater directly to a 12v bench supply. I limited the current a little to stop things getting too crazy too quickly.
I started pushing in PLA filament, as it heated it went through the normal stages of extrusion, then smooth extrusion, then very fast runny extrusion, then brown bubbly extrusion, then spitting and smoke, then finally it was just pushing filament in and a plume of PLA vapour/smoke was pouring out of the nozzle and I had to stop the “experiment” because of the smoke buildup.
I was holding the hotend in my hands the whole time, the mounting portion did get warm, but never anywhere close to what I would call “hot”. I have not idea what temps I hit during that event.
I’m going to re-do this in more controlled circumstances, with ventilation etc and video it.
I’ve done plenty of simulation and testing etc, but what it really amounts to is that there is really zero appreciable heat transfer to the mounting portion during normal use.
@Sanjay_Mortimer regarding your coment there is only one thing that comes to mind, holy cow.
Ops I just read this:
http://blog.ultimaker.com/2013/08/05/product-innovation-dual-extrusion-experimental/