- Joined
- Dec 25, 2011
- Messages
- 10,525
Tim,
First, to get the inner nut off, try running a die nut onto the screw threads backwards. That should clean up the damaged threads next to the keyway and allow the nut to get past the damaged area. If it doesn't, try all of the die nuts that you have. If that still doesn't do it, try an adjustable or split die nut. That should do it.
Differential adjustment of the two nuts on the (probably 3/8"-24) threaded portion of the cross feed screw is how you adjust for minimum end float of the cross feed screw. That is best done with the cross feed nut run off the end of the screw and should be done before evaluating the crossfeed screw and nut for possible replacement. You will probably need a thin pattern open end wrench to hold the inner nut while you tighten the outer one (what used to be referred to as Tappet Wrench). It will probably take several attempts of loosening the outter nut and making a small adjustment to the inner one and then tightening the outer one before you are satisfied with the adjustment. When you are satisfied with the end float (should be less than 0.003"), run the brass cross feed nut back onto the screw and use the dial to measure the backlash. With a new nut, this will probably be 0.002" to 0.003" more than the end float of the screw. With a used nut, it will be more than that. Record or remember this reading. Then crank the cross slide back to the region where it most often runs, and repeat the measurement. With a new screw and a new nut, this reading should be the same as the first one. How much more it is indicates how much wear you have on the screw (independent of wear in the nut). At this point, it is up to you to decide whether to spend the money to replace nut or nut and screw.
First, to get the inner nut off, try running a die nut onto the screw threads backwards. That should clean up the damaged threads next to the keyway and allow the nut to get past the damaged area. If it doesn't, try all of the die nuts that you have. If that still doesn't do it, try an adjustable or split die nut. That should do it.
Differential adjustment of the two nuts on the (probably 3/8"-24) threaded portion of the cross feed screw is how you adjust for minimum end float of the cross feed screw. That is best done with the cross feed nut run off the end of the screw and should be done before evaluating the crossfeed screw and nut for possible replacement. You will probably need a thin pattern open end wrench to hold the inner nut while you tighten the outer one (what used to be referred to as Tappet Wrench). It will probably take several attempts of loosening the outter nut and making a small adjustment to the inner one and then tightening the outer one before you are satisfied with the adjustment. When you are satisfied with the end float (should be less than 0.003"), run the brass cross feed nut back onto the screw and use the dial to measure the backlash. With a new nut, this will probably be 0.002" to 0.003" more than the end float of the screw. With a used nut, it will be more than that. Record or remember this reading. Then crank the cross slide back to the region where it most often runs, and repeat the measurement. With a new screw and a new nut, this reading should be the same as the first one. How much more it is indicates how much wear you have on the screw (independent of wear in the nut). At this point, it is up to you to decide whether to spend the money to replace nut or nut and screw.