Southbend 9B Newbie

Hi All,
I'm new to this forum and new to my recent purchase of a Southbend 9B. I wasn't particularly looking for another project but same ol'story for me, ie started to check some components and found some mighty worn bits. So do I make new parts on the lathe at work,(time consuming and no spline cutting gear, or milling machine?)or try to order new.(possibly costly, availability due to age of machine) Maybe source quality 2nd hand parts?(This forum, or elsewhere?)Guy's at this stage I need a crosslide screw and the nut, or threaded bush that goes with it. The thread is acme but on mine it now looks like whitworth. Thanks in advance Gazza

You don't really need a mill to make the nut. You can buy allthread of the right size, and cut it down to size on the lathe at work for the dials, etc. as for the nut, you could either make yourself a tap or buy one.

Why do you need a new screw? All screws, etc have backlash, and it's not something to lose hair over. Furthermore, have you checked that the play isn't in the thrust bearing for the screw? On my 13" SB, there's over 0.100" of backlash, but 90% of it is because there is a gap between the dial and its mount.

A worn crossfeed screw/nut combo doesn't make it a project lathe. if that's all that's wrong with it, you should be happy. My 10L arrived with spindle bearing issues, no chucks, uneven, severely worn bedways, a low tailstock, and some other issues. My 13" arrived with severe backlash in the crossfeed, a carriage traverse gear with a nasty tendency of loosening and grinding against the leadscrew, and a few gears in the crossfeed power trains with damaged teeth. On top of these issues, both machines were absolutely filthy. The 13" had spent a year sitting in an exposed field, with nothing protecting it but a thick layer of what looked like recycled grease. All of the accessories were found sitting in a rotting wooden box next to it. The 10L had spent over 5 years in an old woman's basement, partially disassembled, getting no lubrication or attention. The carriage and tailstock were in a pile at its feet, and she thought they were seperate machines that she would charge mroe for until I whipped out a copy of HTRAL that I had handy.

Hi again,
No this crossfeed screw and nut has to go. .040" end play and .015-.020" up and down is way too sloppy, plus the acme thread is flat at the base and peak of the thread, mine is that sharp you nearly cut yourself on it
No I'm not going to make a project out of this at present, I want to get it back up to what I consider good and reasonably accurate running order and get some use out of it for my $$$s, a total o/haul may happen at a later date.
Can you buy acme thread bar off the shelf?
Regards,
Gazza

Hi Gazza,

As I see it, there are a number of different approaches:

1) If you have more money than time, you can get a new screw and nut from Miller Machine & Fabrication. $250.00 is a pile of money, but their work is supposed to be first-rate.

2) Decent used parts occasionally show up on eBay. Here is a screw and nut for a Buy It Now price of $35.00. It's for a C model, but you could cut off your existing screw just past the gear, bore a hole, and modify the new screw's threaded portion to fit the hole, and pin it, or whatever. Here is another auction for a model A screw only. Looks to be in good shape. Etc.

3) If you have access to a lathe and mill (at work?), you can make a new 7/16-10 LH Acme threaded screw portion and fit it to the stub of your existing screw. A new nut could be made from bronze (or brass, in a pinch) using the 4-jaw chuck. It doesn't have to be streamlined like the original, which was made from a casting. Don't worry about finding a tap, but grind your own single-point threading tool from a HSS blank.

4) Get creative. I'm not sure about the supply houses where you live, but here in the US, McMaster-Carr sells 1/2-10 LH Acme threaded rod (though only in 6' lengths), as well as brass "coupling nuts" which fit. These nuts are 1-1/4" long, and all you'd have to do is fashion some kind of mounting spigot to attach it to the cross slide. Personally, I'd prefer to stay with original-type parts, but there are other ways to go.

Good luck!

Paula

Thanks Again Paula,
Yes! me too, I'd prefer genuine parts, either new or good 2nd hand to go back in.
To your knowledge can the crossfeed screws of any other Southbend or Hercus lathe fully interchange with 9B?
Regards,
Gazza

If you want acme stock & nuts, have a look at

http://www.greenbaymfgco.com/

Prices are loads better than McMaster-Carr. They have all their stuff in stock, get it by the foot and they're happy to sell small quantities no problemo.

Greg

To your knowledge, can the crossfeed screws of any other Southbend or Hercus lathe fully interchange with 9B?

Click to expand...

Hi Gazza,

The South Bend 9A, 9B, and 10K screws of the same dial type (I.E. - standard versus direct-reading) should be interchangeable. The 9C screw lacks the gear for driving the cross-feed. I have no experience with the Hercus lathe, though it may be compatible as well.

Paula