Well I have an Eldorado Bridge mill, That i picked up new in 01.
After long time I finally came to the conclusion that shoptask them self are no great help in solving my issues. So decided to fix my biggest issue my self.
My machine has/Had so much Z backlash that it made the machine useless for any 3d type work. So for the longest time it was my cut out machine. And if i couldn't cut it in one pass It was deemed useless.
My run out was with in .001 if the Quill stayed up. and didn't move. As it came down it got worse due to the Quill having a ton of play. Quill itself has about .009 slop
(Oh and if i tighten the Quill lock up it would only cause me to snap drive belts for the cnc.)
Backlash on the Quill was .026 . Which means no matter what i did everything was always at angle or stepped.
So with all these factors pissing me off. The guys at shoptask where some help. Together we came to the conclusion that the ballscrew kit would only solve 1 of 3 issues (would only solve the backlash issue)
So after About a year or 2 of living with this and since buying a syil Sx3 cnc. I decided it was time to fix it.
What i came up with is.
Ball screwing the Z quadra lift. And adding The cnc motor to that. But i went one step further. Since this requires the release of the 5th post.
I added a column from a seig x2 and its slide block. Creating a 5th post on the back motor side of the quadra lift. This stiffened it up and made the need for the 5th post un needed.
Well i went from .026 backlash on Z to a .0015 ( and thats cause i don't think theres enough balls in the ballscrew nut)
Just under 7" of z travel
.020 side to side play down to .001 (with out original 5th post locked down)
All the parts for this where cut on a syil SX3 cnc And on a manual Seig super X3
Edit
Forgot to add. Max fps on z rapid was 6fps Now its just under 18fps.