# A lead screw question.



## Tamper84 (Nov 5, 2012)

Hello All,

I have been looking at different lathes for sale (browsing around, nothing in perticular). I have noticed one thing, all of the power feeds for South Bends are done thru the lead screw. Why is that? Or would this be normal for older lathes? Anything good bad or indifferent about this set up?

Thanks,
Chris


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## swatson144 (Nov 5, 2012)

It is simpler and less expensive than two shafts and the gearing. It doesn't much matter as long as it isn't through the half nuts like some of the cheapest lathes.

It is also possible that you can get finer feeds on a 2 shaft system, since there can be a reduction on the feed shaft AND in the apron. Though probably a moot point as I seldom use the finest feed anyway. Just something to look at as a nicety and comparison point. I'm sure some of the better single shafts have plenty fine feed while some of the cheaper ones will require inverting a couple gears from normal threading setup to get a fine feed.

Steve


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## PurpLev (Nov 5, 2012)

2 shafts means longer life for the leadscrew and half nut, but other than that, sharing the leadscrew for threading and for powerfeeding (as long as it's not using the half nuts for feeding) is normal and is very common on older lathes. power feed on the crossslide as mentioned is a nice thing to have too.


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## GK1918 (Nov 6, 2012)

Again I may be right or wrong, I just think the majority will have a keyed feed screw and then a twin
screw is probably on bigger high end machines just my thought.  Correct me, but S.Bends have a finer
feed than an Atlas courtesy of Tubales vidio of his Atlas power feed.  And then my GK is a twin shaft,
which means I can terminate the treading lead screw or, the power feed visa versa.  Power feeds and
crossslide feeds can be quickly reversed as well as both feeding at the same time. (tapers) I cant get
into that cause its complicated (cutting tapers under power).  With my two SBs I run them understand
them and wouldnt trade them.  I could write a book on tricks with these if I live long enough.  Ive run
them for decades with not a problem.  Longjevity tip.  Things seem to come in bunches like, we have
facing days, drilling days, parting days only, this case my habit is to disable the gear train not needed.
Habit release belt tension after use, clean oil and cover for the next day.  Next day uncover oil again,
Once a week polish all hand wheels with chrome polish.  Once a month all machines get a coat of
silver never size wiped down and a mist of chain oil on there ways tables etc then lightly spread with
paint brush. These little habits are my way to servive.  In conclusion I really advise quick change
gear box, power cross slide no matter the make but really not neccesary, just makes life easier and
then, any lathe is better than no lathe.  Just dont miss the bus.


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## Tamper84 (Nov 6, 2012)

Thank you all. I didnt know if only have the lead screw for power feeds and all of was something I should avoid or not. Rest assured, what ever lathe I do purchase, it will have a quick change gear box, along with power cross slide. 

Gk1918, what kind of cover do you use to cover your lathe? And thanks for the maintence tips! You go thru a lot of work, but I am sure it is worth it.

Thanks,
Chris


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