I was wondering, why the v6 isn't shorter. Even the lowest ribs always stay cool. Couldn't one make the hotend shorter by removing half of the upper cooling fins? I guess that would make the action more direct as it gets close to the extruder...
The upper fins are cool *because* they're there. If you make it much shorter, the heatbreak will get too warm for PLA and you'll run into jamming issues.
Ok, good to know! But how is this issue solved for these very short hotends? Like what is sold as "MK 8" extruder? Do they only run ABS? http://de.aliexpress.com/store/product/ ... 72321.html
Those use a larger 40mm fan that cools a heatsink. The heatsink is thermally conductive to the stepper motor and extruder. Both of these components also act like less efficient heatsinks. They tend to get pretty hot as a result.
Correct, you can see the heatsink on the left side of the photo you linked. They also either have PTFE liners (thus limiting the temperature) and therefore aren't all metal, or if they don't then they don't have good PLA performance. Speaking from experience.
