MPCNC (525 compatible) cable guide bowden end
Note: this will work with MPCNC 525
I'm using a Bowden tube to reduce deflection on my z-axis if the machine has to move a long distance and the filament needs to be pulled against the extruder. I made this part to sit atop the cable chain so the Bowden tube can follow the same path. i put the bell design on there to keep the filament from being stressed against any hard edges. all you have to do is drill a hole at the end of your aluminum angle chain guide, slide a 6/32 nut into the bottom of the part and insert a 1" 6/32 Screw. i used a thread tap to tap out the 6mm hole for the Bowden fitting. Then you just cut your tube to length and insert it into the extruder drive and this part and you shouldn't have anymore issues with filament being tugged or getting hung up on long moves.
for the other end of the cable chain, use my fan, shroud/cable guide:
http://www.thingiverse.com/thing:1597239
EDIT: I added a modified version of the cable chain links that has an added support for a bowden tube. i'd print about 6- 8 and space them out along your cable chain. it should add enough support for the bowden tube while not constricting or over bending the tube.
This thing was made with Tinkercad. Edit it online https://www.tinkercad.com/things/leY3gjqLLnO