Topics

Cross slide and compound backlash

Matt R
 

I am in the process of tearing down, cleaning and seeing what needs replaceg on my SB 16/24. Is there a way to measure the nuts on the cross slide and compound to see how bad the wear is? I have the one screw out and can wiggle ithe nut 15 or 20 thou on the screw up and down and lengthwise. The screw looks to be in good shape on the entire length. So do I just need new nuts to get rid of the backlash?

houdini
 

Matt, crossfeed nuts are on e-bay for the going price. i would start there and with the nut you can see if in fact the crossfeed screw is worn, or if budget permits buy one of the complete assy. 

On Saturday, May 16, 2020, 04:21:11 AM EDT, Matt R <mrissmiller@...> wrote:


I am in the process of tearing down, cleaning and seeing what needs replaceg on my SB 16/24. Is there a way to measure the nuts on the cross slide and compound to see how bad the wear is? I have the one screw out and can wiggle ithe nut 15 or 20 thou on the screw up and down and lengthwise. The screw looks to be in good shape on the entire length. So do I just need new nuts to get rid of the backlash?

Steven H
 

Loosen up the gibs on compound and cross slide slightly and set up mag base and dial indicator on front or rear face of slides. Push and pull on slides, read wear on dial indicator at various positions on the screws. New nuts should improve the backlash. The nuts are bronze and meant to take the brunt of the wear rather than the screw.

Steve Haskell

On May 16, 2020, at 8:15 AM, houdini via groups.io <houdini969@...> wrote:


Matt, crossfeed nuts are on e-bay for the going price. i would start there and with the nut you can see if in fact the crossfeed screw is worn, or if budget permits buy one of the complete assy. 

On Saturday, May 16, 2020, 04:21:11 AM EDT, Matt R <mrissmiller@...> wrote:


I am in the process of tearing down, cleaning and seeing what needs replaceg on my SB 16/24. Is there a way to measure the nuts on the cross slide and compound to see how bad the wear is? I have the one screw out and can wiggle ithe nut 15 or 20 thou on the screw up and down and lengthwise. The screw looks to be in good shape on the entire length. So do I just need new nuts to get rid of the backlash?

glenn brooks
 

A good indicator of wear for cross or compound screw and nut is inconsistent DOC and finish when making final cuts. Slight concentric circles in the finish cut means the thread angles on your screw are worn, causing the tool post to ride up and down on the threads as it passes along the work. Same with holding a consistent DOC. A worn screw means sometimes never being able to achieve the same rate of removal.

my SB Fourteen had these same issues. Sometimes DOC varied up to .010” with the same amount dialed in. I had a shop make up a new screw and nut and now it’s rock solid.

BTW, both parts wear against each other. If the nut is worn, you can count on the screw to be worn also. If you are tearing everything down for a rebuild, why not renew the clearly suspect parts and make it new again?

Glenn