Spool Holder Mount for V-Slot or Linear Rail systems

This is a mount for a threaded rod or a bolt (either 8mm or 5/16") to attach to a vertical section of V-Slot or Linear Rail. I used this for a spool holder to mount directly to my 3D Printer. Currently I am using the parts from http://www.thingiverse.com/thing:969358 to hold my spools.

The mounting holes are 20mm apart on the narrow side and 40mm apart on the wider side to allow for either vertical or horizontal mounting depending on how wide your rails are.

To mount to V-Slot, use four 16