Tool slide lead screw for Smart Brown 1024

The screw on my 1024 tool slide is very worn, much more than the one on the cross slide. It isn't fatal as I can tighten gibs for most turning but replacing it is on my list for when I need to advance the compound.

S and B uses a 3/8-10 LH which narrows the choices. There are standard 1018 screws with no tolerance numbers for travel deviation, there are " Precision .009/ inch SS screws, higher precision .003 screws but hard to source in LH, and ground screws that seem overkill for a tool slide ( .0005/ inch ).

The price difference going to the .009 SS isn't so bad but is it worth it to try to find a higher precision screw ? The two backlash nuts should still be OK as they still adjust the non worn part of the screw but will a new screw need new nuts to match ? The rest of the machine is Whitworth but I think the Acme standards are the same as here in the US. I will probably buy the screw and test the nuts but if there is advice on the screw and profile, I would appreciate the help. Dave

Personally I’d rather get a 5 tenths ground screw. Reason is I frequently use my lathes for facing discs, collars, etc that need to be within a thou. With my more worn lathe I’m having to rig up a dti to hit tolerance. Your needs may differ. My good lathe doesn’t need this.

L7

lucky7 said:

Personally I’d rather get a 5 tenths ground screw. Reason is I frequently use my lathes for facing discs, collars, etc that need to be within a thou. With my more worn lathe I’m having to rig up a dti to hit tolerance. Your needs may differ. My good lathe doesn’t need this.

L7

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What he said ..........unless of course its a kick bollock and bite beater when any old bit of allthread will do.

The machine is pretty good for a 1960s vintage machine. I'm not a great machinist but I've rehabbed enough machines that I'm a decent judge. this one has been weird in that other than the compound screw, there doesn't seem to be terrible wear but everything I've been into has been cobbled up or parts missing. The people who used and repaired the machine were evidently not the pick of the litter.

If I have to do the work to modify the screw I will use what is best. A $100+ price difference is better than working to make something mediocre. Dave

Does Bracehand have a new screw? I bought parts for my 1024 from them.
1024 Lathe - Smart and Brown Machine Tools, Bedfordshire

sandiapaul said:

Does Bracehand have a new screw? I bought parts for my 1024 from them.
1024 Lathe - Smart and Brown Machine Tools, Bedfordshire

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They don't have any but may have blanks for the backlash nuts. I sent an email to Greenbay Manufacturing about making a precision screw and asked them if new nuts need to made or not.

I'm also looking at the spindle bearings as I can get a thou or less movement if I push on a bar. I get my best finish when I'm taking a deeper cut and I wonder if the bearings might need a little adjustment. Dave

beckerkumm said:

The machine is pretty good for a 1960s vintage machine. I'm not a great machinist but I've rehabbed enough machines that I'm a decent judge. this one has been weird in that other than the compound screw, there doesn't seem to be terrible wear but everything I've been into has been cobbled up or parts missing. The people who used and repaired the machine were evidently not the pick of the litter.

If I have to do the work to modify the screw I will use what is best. A $100+ price difference is better than working to make something mediocre. Dave

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it sounds like you have your answer

If the consensus of the group is precision ground, I will go with it. I wasn't sure if a compound screw benefited enough to be worth the custom effort. Dave

Nook, Roton, or Green Bay don't offer custom precision ground leadscrews in my size. I'm trying a couple other sources but given the screw is for the tool slide and will only move a couple of inches, I may have to compromise on a .006/ft rolled one. Dave

Try HelixLinear.

I know they have ground RH 3/8”-10 Acme, not sure if also LH.

L7