Clean gantry, better drag chain setup, I’m happy… for now.
If there was a “K40+++” this would be it.
Looks very nice. Great job.
nice work hold down pieces
The chain is connected to the side of the moving gantry. Then there’s another piece that’s attached from there to the back of the machine where the air comes in. I 3D printed both brackets, one on the head and the other on the side.
I’m take a picture when I get home after work.
There are two completely separate chains here, one at the top, and one on the side. They both connect to the side plate that’s attached to the moving gantry. Somewhat similar to how an X-Carve is setup: 
The bracket on the right is attached to the moving gantry, and it has two connecting points, one at the top to receive the upper chain, and one on the bottom, that’s for the bottom chain. The airhose (and future wires) simply snake through it from the top to the bottom (or bottom-up, whichever you prefer.)
That would make for a rather limber piece of cable chain. 
Modeling the bracket and attached cable chains and it looks like this, viewed from the side: http://www.thekirchners.net/bracket.png
http://www.thekirchners.net/bracket.png
The upper gantry has 4 screws on the side, the bottom two pull the idler that holds the belt tight, and the upper two hold the actual beam. The bracket is designed so only the upper two need to be loosened, the bracket slid over them, and screwed down. The bottom screws will be accessible through the larger holes.
Is this 3d printed? Do you have the files for it if it is?