The X-axis leadscrew had been damaged in shipping. The damage was not bad enough that it didn't work, but I wanted to get the adjustable backlash nuts to help reduce backlash and since I would have it apart I may as well change the leadscrew. The end of the leadscrew had been damaged enough such that it would probably not work with the CNC conversion later so it would have to be changed eventually regardless.Changing the leadscrew was pretty simple. First turned unscrewed the two screws holding the bearing block on the end of the X-table. Then I turned the lead-screw out of the leadscrew nut. The leadscrew nut could then be replaced with the new adjustable backlash model. Prior to doing so I cleaned and oiled the gibbs and ways, since it was all exposed and easy to get at that point.
The next step was to remove the crank and the dial from the old leadscrew by first removing the hex nut. Be careful not to allow the key to fall out from the keyway in the shaft if you need to reuse it. It is small and can be very difficult to find on the garage floor. Not that I know, I am just assuming that this would be the case. I next placed the new bearing block on the new leadscrew and assembled the dial and crank onto the new leadscrew. The new leadscrew included a key, a washer and a lock-nut. I've read to be careful not to over-tighten then nut as this can damage the ball bearings in the bearing block. I therefore used care to tighten the nut only until I could feel no more slop in the assembly.
I did find that the key was a little oversized and needed to be filed to fit properly. Aside from that it all fit together quite nicely. One thing that I was disappointing in was the shallowness of the mark on the bearing block which one would use, in conjunction with the dial, to determine the travel of the table. If you look at the picture below you may barely be able to see what looks like a vertical scratch at the 12 o'clock position. This is not much more visible by eye than in the picture and I will have to try to scribe it more deeply later. I realize that this bearing block is intended to be used mainly on CNC machines, but if they were going to go to the trouble of marking it at all they may as well have done it deeply enough to be useful.
Once the leadscrew assembly was together I screwed it onto the X-axis table and slid the table into the ways. I then adjusted the ways until I could feel no play, but the table slid with little resistance. At this point I proceeded to thread the leadscrew into the leadscrew nut. I happened to have bought the 19" leadscrew, despite having the 18" table. This will allow me to upgrade the table size later, but it also allowed easier access to the leadscrew nut for backlash adjustment. I was able to have the table in the ways while having the nut exposed enough to adjust. This is done by loosening the set screw in the middle of the nut and turning the two screws one either side until they were snug. Then you back off of the outer screws by 1/4 turn and snug up the set screw. All said and done, I got the table assembled and backlash was down to about .003" which is way less than it was before. I believe that I can get a little more out if I really fiddle with it, but .003" is fine for manual work. I'll obsess about it once I convert to CNC.
Further improvements I intend to make are to replace the other two leadscrew nuts, and to make and install way covers. After that I'll have to tram everything up and I'll be ready to cut some more chips on her.
