I am starting out on a conversion of the Grizzly G0720 which is Grizzly's version of the Sieg SX4. First up, I am working on a ballscrew conversion. After looking around quite a bit online, I ended up ordering the linearmotionbearings2008 screws, nuts, and bearings off of ebay. These appear to be the same product as homeshopcnc is offering for quite a bit more money, or at least the drawings appear to be identical. I would have liked to order domestic, but the costs appear to be prohibitive for similar quality.
With regard to end fixity (who invented that word anyway?), the G0720 has a fixed-free screw support setup on both Y and Z axes. As part of the conversion, it looks to me like it would not be difficult to add an end bearing on each axis to provide additional support to the ballscrew end. On both axes, the ways extend back almost all the way to where the column and base meet. The saddle and column can't usefully get there on this mill so it would appear straightforward to locate end supports there without sacrificing any travel. This obviously would provide more support to the screw and potentially take some loading off of the nut. I haven't seen much discussion of this with the other builds so am curious to hear if anyone here has contemplated this with other mill ballscrew conversions.