50mm Spool Support For Hypercube

I am building a Hypercube printer, and needed a mount for a filament spool, so this is what I came up with. It may be similar to some others posted here, but I designed this from scratch.
The spindle has two 608 bearings that run on either an 8mm or 5/16" shaft. Amazinglly, they only differ in diameter by less than .001 inch. I used a 6" long piece of 5/16" rod that I threaded 5/16" UNC on one end. You could also use a 5/18" X 6" bolt also.
You will notice that the mount has a slot and a boss for two 5mm screws and nuts to pinch the rod if it doesn't fit snugly. The rod I used was a tight fit and took considerable force to get it pushed into position, so I didn't use pinch screws. YMMV.
The 608 bearings will press firmly into the counter bores on each end of the spindle, and I placed an 8mm washer between the inboard bearing and the mount.
The arms on the spindle are so you can easily hold the spindle from turning when you tighten the nut.

I printed the spindle and nut with sup