Extruder Cable sag with MMU3 enclosed installed  

Extruder Cable sag with MMU3 enclosed installed

Hey all!

First time posting and new to 3D Printing so please be patient with me.

That out of the way I encountered an issue with my core one with MMU3 installed where I would have a specific print fail repeatedly in the same way. 

Anyway I traced the issue down to a specific tool path in my print where the extruder would move from back right (if facing the printer) to front right and then across to the front left for a particularly large print (early stages) and what would happen is the cable would droop just enough to move in front of the idler disengage lever and then as the extruder comes across to the  left the cable catches on the lever and eventually snags tight and causes the whole extruder to skip back, the print then continues but about 3cm to the right of where it is meant to be leaving the first 9mm or so in the original position. The printer does not indicate any failure at this point and continues to print as normal until the snag happens again and there is another major Layer shift.

The PTFE tube with the Velcro straps is supposed to provide enough tension to keep the cable up but I have noticed that it does sag down in certain situations and much worse if like me you decided to clean up the look of the cable run a bit by removing the ptfe tube. 

I was at a loss on a solution until I came across a 3dprint on printables addressing the very issue (seems I am not alone in this) below can be used to find the solution. 

CORE One – Horizontal Cable Guide by Leif Lumby Henriksen | Download free STL model | Printables.com

However I was unable to find any nylon box strapping to make this fix work so at a loss I turned to my brother who is a much more experienced 3d print enthusiast than I am and he suggested a "cable snake" aka a cable chain and that turned out to be the perfect solution.

I used the brilliant open cable chain design below and adapted it creatively with some zip ties to my core one (I dont currently have the level of experience needed to model a proper solution to interface with the swing arm and extruder so zip ties was the go)

It requires about 19 links and 19 clips to close the cable in after, I used the 55 degree links which was perfect for the length and bend radius needed for the cable to clear at all extruder positions.

AR cable chain link opened by aroo | Download free STL model | Printables.com

I hope this can help someone in a similar position and hoping to see some native core one designs show up in future or hoping that I can learn to model it myself and make it available.

Robin