This is a dangerous thing the following reasons:

-It's made without any science.

- Nichrome around steel: many chances for a short sooner or later thus many chances for, at least, extruder controller death.

- It constantly leaks some baked-rebaked-ultrabaked abs (volume like a drop of water every... +/-10cc of extruded ABS), the fumes are everything BUT healthy.

The electrical failure plus catastrophe side is reinforced by a low mass design and thermistor most probably not placed in the right place. That leads this thing to the need of 255C degrees as a working temperature.

I never dared to upload this for all those reasons, however...
...I've noticed an increasing number of visitors in the place where the pictures for this thing are: aubenc.imgur.com/hot_end_aka_mk45 and I need to say again:

Don't do it!

Run the risk you want for your printer but, at least, think about the fumes of the baked abs!

I'm expecting this thing to fail... (some 3 months wokrking without the smallest ridiculous failure) and then I'll try to address the issues this thing have. May be nobody will be using an MK4 like hot end anymore :-D

UPDATE: Nov 27, 2011
This thing died yesterday :-( To be honest, I killed it :-P (set the temp to 2255, RepG, at least v0024, only reports up to 255 and doesn't limit to this value... using just one byte?)

Bad news is, everything in the hot end melted together and now it's impossible to disassemble and see the origin of that little leak.

Good news is, nothing else was damaged (I guess I saw the smoke in time).

Conclusion: bot1334 has been using this thing for almost 8 months with zero maintenance. Before this, she was more time down for repair (one of the 3 MK4 that she used in half a year) than actually working.