You may have a hard time getting and keeping the hotend to/at temp. You created a very large heatsink. I would suggest a very thin nut, to keep the transistion zone as close to normal length as possible.
I am almost back to the groove mount at this point. @Matt_Barth Adding the L-bracket and the nut to the e3dv6 makes for a very large heatsink? If the bracket is steel it isn’t very conductive to boot and in a normal operation isn’t the ss heatbreak the one transferring the heat to the ALU heatsink anyway?
The problem I see so far, the one i saw from the first post is that the transition zone gets way too large…
With a brass or aluminum nut, and an aluminum bracket, the transition zone won’t change appreciably. In effect you’d just be extending the heatsink length. Which is totally fine and won’t affect the hot block, since the entire point of the E3Dv6 heatsink is to remove heat as fast as possible.
@Florian_Ford 2mm is a bit thin… I would use 3mm as minimum.
I don’t get, why it must be mounted that way in the first place… Looking at this, I have a dozen other ways of mounting this just popping up in my mind. Maybe show us the rest of the carriage to give you a better advice…
I am trying to have the nozzle as close to the rods as possible and the only way to do this is to have the groove mount up above the carriage, just like some deltas (rostock) do, using posts to connect the groove mount to the effector plate and even some cartesians (rigidbot -https://is.gd/sKhLP8) use the same principle. To maximize Z, to avoid the extra components and to clamp the hotend as close to the nozzle as possible, something like what I sketched should be possible. Because I and many others already have v6s, I must find a way to make this happen, if possible, for this specific hotend.
Cut a slot in the metal bracket so it can slide between the bottom two cooling fins of the hot end (similar to the original groove mount at the top). If you are handy, you could make that plate a tight fit plus add a clamp screw. This way, no need for the nut at all, and no heat sinking where you don’t want it. It will possibly require a different cooling shroud or modifying the one you already have. I’m lousy at illustrations, but I can elaborate if needed.
@Chris_Setla_kaptain It would be easy to mount this way, but hinders the proper cooling of the two lowest fins. These are the most important fins of this type of heatsink. Why not printing a small cube with a cylindrical hole for the hotend in it? The box can be screwed to the mounting-slot and does hold the heatsink all around. Something like this (without the weird looking fans 
)
So anything but a groove mount would be detrimental to the proper functioning of this type of heatsink (the pic still looks like a groove mount to me). The cylindrical hole that would hold the hotend would still need the fan blowing from one side and the blown air escaping somehow from the hole.
@Rene_Jurack The metal bracket will add far more cooling than air blowing in between those two fins as steel or perhaps aluminum has a far higher thermal conductivity than air.
However, the posted carriage illustration adds a whole new dimension to the question. Perhaps not mounting as much as air flow when mounted that way.
@Chris_Setla_kaptain I can fit a 30mm fan in there and it will have enough room to take air from the back of the fan to blow on the heatsink. My main concern, after all the comments, remains the longer transition zone from molten plastic to solid, which means less control over extrusion. This applies for the situation in the pic, not the slot-in-bracket situation. But cutting a slot in the metal bracket is far more work and specialized tools than a hole… it doesn’t make much sense to do this over the groove-mount.
@Florian_Ford Cutting the slot with a hack saw is easy and quick… drill the hole first, then use the saw. You need access access to a vice to hold the bracket though.
The way you have depicted the carriage, there is no free movement of air for the bottom two cooling fins. This WILL enlarge the melt zone, all by itself, and it will cause problems.
There’s a 30mm fan in there, it was hidden in the previous pic. It is a bit crammed, but the air blows on the lowest fins.
A fan blowing ON the fins will not cool them, it is the airflow PAST the cooling fins that cools them. You need a full, unobstructed path for the air to flow for it to have any effect… your carriage design does not appear to provide that.
A channeled airflow at the exit so that the airstream goes upwards instead of hitting the reinforcement would solve that obstruction you see there. The way I see it, the air can get in between the fins at the back but it doesn’t flow in a laminar fashion at the exit because of the plastic bridge. If I design a sloped exit of the air so that it will be directed to exit at an angle that turbulent exit airflow you would expect from the sketch above would be avoided.
