I ordered the wrong E3D-Hotend. For my Ultimaker i needed one with "bowden extrusion" and I bought "direct extrusion", since it was a bit cheaper and now i had to improvise a way to get my bowden-tube attached to the hotend.
I have designed this adapter for this:
promising hotend mount.

All it does is grip into the grooves on the upper part of the E3D-heatsink and include a nut-trap for an M6-nut, since this has proven to be a very reliable way for fastening your bowden tube to something.

Note: the SCAD-file includes a model of the top of the E3D-heatsink, maybe you want to use it. The measurements are all correct, since they are the original ones from E3D. You can also add a tolerance like i did.

P.S: You are welcome to edit this Thing via OpenSCAD. Given that you can read my code ;-)

=============development history===========

Update 12.10.2013:
Uploaded the photos. As you can see there was a little trouble with printing the overhang, but this only inflicts the looks of the thing not its function. The fitting is tight on the head and nut, the alignment looks good...
The only thing that needs some adaption is that the faces of the adapter do not yet fit to the faces on the printhead.
On Monday i will try if it works anyways.

I have mounted the new hotend to my Ultimaker. The bowden-adapter works fine: the alignment of extruder barrel to bowden tube fits so there is no additional friction on the filament.
BUT it is about 5.5mm too long on the y-axis. I had to move my endstop-switches by drilling new holes for them into the left frame.

Maybe this will be fixed in a later version, where the outer shape of the adapter has smaller y-dimension.

I will send pics as soon as i can borrow a camera again.

Update 21.10.2013:

I found that E3D provides the blueprints of their heatsink on their page, so i took the values from there and replaced it with my own measurements. I also have reduced tolerance by half and made the piece where the bowden tubing comes in longer, so the alignment tube-heatsink will be more strict.
The outer shape is now pentagonal maybe this will help to keep the surface intact during printing.
Also I changed the fitting of the adapter to the hotend mount, so hopefully it will fit this time.

I havent printed it out yet, but -by chance- will do so tomorrow.

Update 22.10.2013:

I have found and corrected an error in the fitting for the E3D-heatsink-head. It should now work much better. I have also added three different tolerances since the resolution of your printer highly inflicts the accuracy of the fitting.
Also the files for OpenSCAD are uploaded so you can edit it further.

Update 22.10.2013-later:

I have used the 0.3mm tolerance and still had to use a bit of acetone to get a proper fitting. The alignment tube-heatsink is now perfect. The Nut also fits perfectly into its trap.
I think this is as good as it gets. If anyone wants a model with more tolerance then just write it in the comment section below, or use the code i provided.

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