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SM 9" Ultilathe Crossslide nut and screw

This thread peaked my curiosity, so I ventured on another backlash reduction x-slide nut creation.....

SplitNut2.JPG


With this nut I can tweak backlash down to 1/2 thou from 1-1/2 thou (original nut), however it's tight at the extreme ends of the lead screw which is to be expected of a worn screw I guess. Is backlash really worth chasing if you know about it and compensate?
 
YYCHM said:
This thread peaked my curiosity, so I ventured on another backlash reduction x-slide nut creation.....

View attachment 22772

With this nut I can tweak backlash down to 1/2 thou from 1-1/2 thou (original nut), however it's tight at the extreme ends of the lead screw which is to be expected of a worn screw I guess. Is backlash really worth chasing if you know about it and compensate?
Click to expand...
Its worth chasing on a mill, but backlash on a lathe really isn't important as long as you are aware of it.
 
Some people feel that excess backlash can adversely affect parting (chatter, poorer cutting performance). As to why this would be I cant really say. One would think once the lash is taken out as you in-feed, screw threads are fully contacting against nut thread, it should be the same right? But maybe the devil is in the details as you are hand feeding at non-perfect handwheel rpm, that micro-momentary pause + some slop could maybe initiate chatter & then it worsens on on its own. I dunno. Parting is one of hose things where pick one of 7 possible issues can cause problems. But I've heard people say when they replaced their worn feedscrew or tightened the ABL nut the problems went away or diminished. Now did they also reset their gibs while doing this job & that contributed to cutting improvement? Hard to know.

Now that my ABL nut is tighter I feel like the infeed control is crisper & maybe overall finish has improved all things equal. Maybe its just allowing the table lock to hold better. But it comes at the expense of feedscrew & nut wear. I have a spare so not too worried. I'll post some pics of my feedcsrew assembly but its nothing special. What you made on your own is an improvement over what is standard on my lathe.
 
YYCHM said:
With this nut I can tweak backlash down to 1/2 thou from 1-1/2 thou (original nut), however it's tight at the extreme ends of the lead screw which is to be expected of a worn screw I guess. Is backlash really worth chasing if you know about it and compensate?
Click to expand...

I just read this again. Do you mean just pushing & pulling on the table you only displace 0.0005" to 0.0015" (or dead band in the dial = same thing). That's nothing. Maybe even considered too tight & premature wear? I always assumed 0.010" was a normal starting point & wear compromise. What do others set theirs at?
 
PeterT said:
I just read this again. Do you mean just pushing & pulling on the table you only displace 0.0005" to 0.0015" (or dead band in the dial = same thing). That's nothing. Maybe even considered too tight & premature wear? I always assumed 0.010" was a normal starting point & wear compromise. What do others set theirs at?
Click to expand...

I messed up using the thou term again. Initial dead band dial backlash was 0.015", final backlash is 0.005". So 5 thou v.s. 15 thou?
 
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