Paul-
It is possible to straighten the screw stock with 2 "V-Blocks", a granite surface plate and an arbor press, but it takes a while to get the proper feel for it. You need to roll the screw on the granite, and look for the "light" between the screw and the granite, or use a feeler gage. You can then bend it back to the proper shape when you find the high spots. A dial indicator on the arbor press will help with the deflection required to straighten a certain bend.
Another idea is that the second nut needen't be a nut at all, it could be a bushing that rides on the OD of the thread. One additional trickier idea is to have moving bushings that suppirt the screw. It would consist of a bushing over the screw, and a support that is mounted to the linear guides of your machine. A magnet would hold the block in contact with your moving carriage, and as it got to a certain distance from the end (say 1/3 travel) it would hit a stop, and get left behind as the carriage continued down the travel. This way the unsupported length of screw is 1/3 of your travel.
Neatman
Neatman  |