After dozens of test prints, I have a good understanding of what's lacking in the MK 1 printhead, but first the good points. The first iteration had the minimum requirements to produce a decent print. It had a sturdy mount for the clone Titan and E3D V6 hotend. It also has a 50mm cooling fan blowing into a cone that directed it just blow the nozzle tip, although after swapping to a clone Volcano heatblock which puts the nozzle 8.5mm lower, I had to use some gaffer tape to redirect the airflow down a little. Will have to figure out new dimensions to suit the longer dimensions.
Starting with Mk2, I wanted to address the part cooling issue and also add a mount for an original Antclabs BL Touch bed leveling sensor that just arrived in the post. I chose a mechanical sensor instead of a filed proximity type because up until now I haven't finalised what print bed material will go into the future production version of the Mission 3D printer yet. In my opinion a high quality mechanical sensor is the best choice for glass or any of the new print surfaces now on the market.
I also wanted to experiment and hopefully develop a tool-less hot-swappable printhead module for maximum convenience going from a 0.4mm nozzle to a 0.8mm one for example. With the low cost of clone parts, it was feasible to swap extruder, hotend, bed leveller and fan all in one. However, after awhile i realised the idea would be too costly and wasteful. Plus I found that the overall weight of everything was a mit much for even very strong neodynium magnets. Perhaps a magnetic system would work better if it was a lightweight Bowden system, maybe later... I also felt it was necessary to tidy up the whole printhead appearance for a better look.
So at the end of Mk2 development, the magnets are out but the part cooling fan setup and BL touch mount is looking good! On to version 3!