Ballscrew Slop Question.....Solved!

Hello All, Thanks again for all the great hints you gave me to try
and get rid of the .002-.003 slop I had each way in my new
ballscrews. First of all, the slop was in the bearings in the left
hand end-cap of the Bridgeport. Here's what I did. I figured that if
I were to add a shim between the two inside races, I would
essentially add preload to the two bearings, and eliminate the slop,
right?? Wrong! I added a .004 shim and when I reassembled everything,
there was .004 slop each way for a total of .008, I was creating more
slop!!!!! for the life of me couldn't figure out what I was doing
wrong. Then on a whim, I miked the bearing races (width) the outer
race was .607 and the inner race was .604-.605, AH-HA! there already
was preload and I basically took it out with the addition of the
shim. Now I made a new shim to add between the outer races, to give
it more preload( I removed the shim between the inner races) I
started with .004 and upon reassembly, I found that there was
about .001 slop each way for a total of .002....not bad, but I wanted
better. I removed the .004 and put in a .006, reassembled and
viola, .0005 each way for a total of .001 slop. Much better for CNC
work. However, now there is a slight drag on the handle, and the
bearing is a little noisy. I'm sure that the bearings aren't made
for that much preload, and I'm probably shortening their life span.
I'm also sure that proper thrust bearings are the only way to go, and
I will probably invest in them, but this is surely a low cost
alternative. John