Cross Slide Feed Nut

D

ddickey

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H-M Supporter Gold Member
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Apr 21, 2016
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Good morning,
Can some explain to me how to adjust these?
One of the socket cap screws has stripped the nut part way into the threads. I'm considering tapping one size larger.
Thanks

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Can you post more pictures. Just that one is not enough information to make a determination from. How about a shot of the top of the cross slide where the bolts go in that hold nut in place. Is there two SHCS and a set screw with a cone point? How about a end view of the nut? Manufactures have made several variations of the split nut over the years and some have different features too. What brand of lathe is this off of? Ken
 
Unfortunately it's is back together and I'm heading out. Here is a pic of the top of the slide. If you look from the ends it has a slight angle on the top. The cap screws will turn straight onto the cross slide lead screw which seems odd.
It is an Acra-Turn.

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Most cross feed nuts are hand fitted at the machine when built. If the SHCS are hitting the thread when tighten, they need to be faced off until they do not bind against the screw. Should have about .030" minimum clearance so there is no chance of it touching the cross feed screw. As for adjusting the slack out of the screw, in theory, you should be able to tighten the middle screw until the nut halves get tight on the cross feed screw, then tighten the SHCS's. But if the nut has sufficient wear, this adjustment will not work. Have to go to plan B.
 
It looks like the screw between the two nuts should be hitting a wedge of sorts that sets on top of the two nuts. I'm guessing you'd just snug the two cap screws to the individual nut halves and tighten the screw between to two cap screws to drive the two nut halves apart? When you get the appropriate back lash tighten the two cap screws to lock the two nut halves in place?

Bruce
 
4gsr said:
Most cross feed nuts are hand fitted at the machine when built. If the SHCS are hitting the thread when tighten, they need to be faced off until they do not bind against the screw. Should have about .030" minimum clearance so there is no chance of it touching the cross feed screw. As for adjusting the slack out of the screw, in theory, you should be able to tighten the middle screw until the nut halves get tight on the cross feed screw, then tighten the SHCS's. But if the nut has sufficient wear, this adjustment will not work. Have to go to plan B.
Click to expand...
Maybe they don't hit the feed screw but when you tighten them you can't move the slide. This is why I thought they impinged on the screw.
 
ddickey said:
Maybe they don't hit the feed screw but when you tighten them you can't move the slide. This is why I thought they impinged on the screw.
Click to expand...
Cut you a .005" shim and put under the nut and cross slide and try it again. If it gets better, may have to put a thicker shim under the nut. But be careful, if the cross feed screw is not running parallel with the slide, the shim is not the cure. I have had to place shims under leadscrew nuts over the years on some of the lathes I've worked on. Just have to play with it and see what works best. Sometimes the screw thread does not get cut parallel to the mounting surface. Especially ones that have tapped threads in the nut.

Ken
 
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