Bowden addition for Bondtech LGX Mosquito (v1) extruder

First - if you want this and you have the LGX Mosquito extruder on your Prusa and the shipping isn't too much money, just buy the v2 sensor enclosure from Bondtech. It can attach a M6 bowden fitting directly I think.

Second - Bondtech support were great and when I explained that for a cheap part it would end up costing me $50 with shipping, they were happy to share the v2 STL. I tried to print it but could not get enough precision and strength as they get with the SLS 3D printed nylon parts. The v2 box I printed in ASA was too brittle though after increasing the side slots, so that the grabbing arms could flex over a longer distance it did not break. I also needed to start adding a % size compensation as it looks like ASA prints smaller than nylon. So I would have needed to start adding a factor, printing and re-testing. 

But often the simplest solution is the best and I had the idea of just putting the bowden fitting on the v1 enclosure box. After importing the v1 sensor enclosure into solidworks I could see that there was just enough material to tap two M3 holes, attaching a thread that would fit a M6 bowden tube fitting to the top of the v1 sensor box. If I was able to drill the holes in exactly the right place. And it worked out.

It is far easier to put the printed part on the underside of the v1 sensor box and to mark and drill the holes from there. I drilled a 1.5mm pilot before using a 2.5mm drill and then tapping for M3 bolts. The bolts were the ones from the Prusa spares kit - any will do but make sure the heads are not too big and that they are not too long and do not protrude from the bottom of the sensor box. Ensure the bowden mount is concentric with the filament path when marking and drilling. If you get it only slightly wrong the filament path may not be as smooth. If you get it very wrong the sensor box should still work, but you don't be adding a bowden fitting to that part, there is not enough room for a second set of holes.

Don't even begin to try this unless you have sharp drills and taps, and a drill press with good accuracy and low runout. Mine isn't fantastic but it's accurate enough. The M6 thread is printed and depending on your printer might work but it will always be better after cleaning it up with a real M6 tap. Tapping the M3 bolt holes into nylon is easy - it is a very easy material to cut, just don't tighten the bolts too much. There is not a lot of strength required here just enough to hold the tube as the extruder moves around.