When I completed the build I noticed that the moving jaw of the vise was very sloppy (it is $15 at HF after all!) so I got some scrap 1/2" nylon sheet and went about coming up with a way to stop the unwanted side to side and rocking motion. I also wanted to incorporate some cheap thrust bearings on the rollers.
1. (2) 1" threaded nylon spacers -home depot $1
2. (6) thrust bearings- McMaster-carr Part Number: 6655K13 $2.06 each
3. (1) 1/2" thick nylon routed out
4. (2) 10-32 x1" & 1/2" fine thread screws.
This seems to really tighten up the sloppy movement