Lathe Cross Slide Problem

[EdK]

I think this may work. I kept removing material until the nut would travel the length of the lead screw without bottoming out on the trough. That leaves only .090" from the crest of the major diameter of the thread to the bottom of the nut but I think that should be adequate. With that phase done, I moved on to mounting the nut to the cross slide and tried running it through the full travel and it's binding so badly that the hand crank won't turn at all. Not knowing if it was binding because the nut dimension is too long or too short I scratched my head for a few seconds and realized that I could loosen the mounting screws and if the binding went away then I would know the the dimension is too short. That ended up being the case so after scratching my head some more trying to figure out how much to shim the nut I had another realization (wow, two in a matter of minutes). I loosened up one screw a half a dozen turns and then started loosening the other screw 1/4 of a turn at a time and tested for binding. At 3/4 of a turn the binding had lessen to the point of just being slightly harder to turn than I liked. At a full turn it was perfect the full length of travel. Since the pitch of the mounting screw is 32TPI, it was easy enough to calculate that I needed a .03125" shim.

That's next, make the shim and test again. The problem with adding the shim is that I don't know if that extra length is going to cause the nut to rub on the trough. I guess I'll find out soon enough.

Ed