Thanks for the suggestion on cutting into the di2 cable, it gives just the room I needed to fit a 30mm axle in a BSA bottom bracket on a titanium frame with 3 di2 cable that before where rubbing.
As you can see I have 3 cables in the way, the 4 way junction is in the down tube with two cables going to up the seat tube to the battery and front mech and one cable going down the chain stay to the rear mech. Your design may vary!
First disconnect the battery!
Then very carefully with a Very sharp craft knife I trimmed off around 50mm of the rubberised outer sheath to reveal the red and very thin black inner cables
The trimming was made harder due to doing it whilst still installed as the I can't remove the 4 way junction (in the down tube) as there is not enough slack in the cable to the handle bars which is in a heat shrink wrap with the rear brake hose. If I cut the heat shrink I would have to unwrap the bar tape and disconnect the hydro pipe to put fresh wrap on. More trouble than it is worth.
You may notice I did nick the black cable a few times, so small bits of insulation tape required.
It's now I also plugged the battery back in and tested to see if it still works okay!
Now to stop the axle rubbing away the wires
I found this bottle of 'Simple Kind To Eyes Eye Make-Up Remover 50ml' the perfect fit. Purchased in UK Superdrug stores on their travel toiletries section
34mm external and 32mm internal. It is nearly a perfect fit inside of the threads.
Trimmed using a Dremal with a disc cutter, you gotta get the ends square (jig required)
Length is critical if you don't want it to spin, so measure the width of the BB and subtract the depth of both bearing threaded bits. mine was 68.5mm -15.5mm -15.5mm = 37.5mm
At this point I untwisted the two inner cables so they flat against the inside of the BB
The bottle goes in carefully pushing the delicate cables out of harms way, top or bottom, it's up to you
Then install the BSA30 bearings and align the bottle to sit in the center away from the axle
Tighten the bearing to keep the bottle in place and to stop from spinning
Beautiful
And install the 30mm crankset, It should spin without any rubbing. and not mangling the cables
Job done. After spending this much money I thought I better do it right!
You may ask why bother to trim the cables, just use the bottle, Well, it doesnt fit, the di2 cables are too fat and they just push the bottle onto the rotating axle. nfg.