Almost doubled my Y axis speed with this mod. Used 3/8-12 ACME rod and nuts, carbon steel. Running dry with no lubricant.
Old Y axis velocity was 17 with acceleration of 10.
New Y axis velocity is 30 with acceleration of 15! Just a hair short of double the speed, awesome!
The bumping sound you hear is the acme rod hitting the hole though the side of the printer. I plan on adding a plastic bushing form Lowes to stop this sound and guide the acme rod.