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Thread: South Bend 9 owners, a question please?

  1. #11
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    A lot of big lathes have one screw to put drag on the compound.
    A Bridgeport table 1 or 2..

  2. #12
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    If you can find a roll tap it might tighten the threads, and fit new screws. If the screws are rocking with the movement of the slide though the holes might be too oval to save.
    Peter - novice home machinist, modern motorcycle enthusiast.

    Denford Viceroy 280 Synchro (11 x 24)
    Herbert 0V adapted to R8 by 'Sir John'.
    Monarch 10EE 1942

  3. #13
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    Just make setscews with a tighter fit..

  4. #14
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    Mar 2002
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    Kirkland, Washington
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    I have had a SB-9 for over 30 years and used it a lot. There has never been an issue with the gib screws. I would suggest that a previous owner "cleaned" the threads with a tap. It is possible the screws are not "factory" as well.

    How to repair is the question.
    1) if the threads in the casting are usable and a standard size, then long set screws and matching nuts are an option.

    2) If single pointing threads is an option, then making new screws with an over-sized diameter and correct pitch would be a choice. In this case loosing a gib screw would be a royal pain in the backside.

  5. #15
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    Chilliwack, BC, Canada
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    Allen head setscrews with lock nuts will be the easiest fix by far. He's got enough other things to do for getting the shop set up and machines running that he doesn't need the "busy work" of single pointing screws of that size. It's a darn good idea mind you. But it would be a lot of busy work at this point when there's lots of other mainstream jobs to get done that have far higher priority.

    I had not thought about the idea that over time the gibs pulling back and forth might pull on the screws enough to oval the threads a little. That's possibly what has happened. The lathe is not worn out by a long shot. But it's seen it's share of use. It would explain the looseness of some of these screws. Mind you I've seen brand new nuts and bolts that fit that loosely too. So it's not like they are wallowed out badly enough to look at going up a size.

    With the proper length allen set screws and smaller size nuts the "fix" won't even look all that bad in a nice low profile sort of way. I'm pretty sure that they are 10-32 by the looks of things. And if so I've even got some smaller hex size nuts off some piece in the past which fit that size that he can have.

  6. #16
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    Oct 2002
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    Russellville, AR
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    Take the screws out, insert some monofilament fishing line with enough sticking out to hang on to while putting the screw back in. That will provide enough tension to keep the screws from moving but will allow easy adjustment.

  7. #17
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    Loctite can take up 6 thou easy..

    Am I really the only one here that thinks when you wind the slide back and forth and the gib screws are wiggling , that the shaft that moves the slide may be bent.. ?

  8. #18
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    I'll try that again because I agree that it SHOULD work. But some time back when I was trying to find something to stick in which would give the proper sort of firm drag for this sort of adjusting I tried monofilament on a few sizes of screws and a few sizes of mono. On a really sloppy 1/4" bolt and nut a strand of 20 lb stayed in place fairly nicely. But on a 10-32 even some very fine 8lb I've got just cut like scissors. I had a bit better luck with some Spectra line on the 10-32 but it migrated away and fell out after about 6 back and forth two turn adjustments. But I may try it again here since it may work for here. The Spectra worked best when wound around the threads of the screw so it actually wrapped around the screw about 3 to 5 turns.

    But I think I'll have the longer setscrews and nuts handy in case the machine proves uppity.... It's worth a try again though. I'm keen on finding a "friction drag" method that doesn't wear out or fall out.

  9. #19
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    Quote Originally Posted by 754 View Post
    Loctite can take up 6 thou easy..

    Am I really the only one here that thinks when you wind the slide back and forth and the gib screws are wiggling , that the shaft that moves the slide may be bent.. ?
    But 754, I want to also be able to adjust them later on. Not be locked. So unless there's a "thread drag" product as opposed to usual "thread locking" options it's gotta be something else. And even if I use the blue or violet I found from trying those that it starts out with a good drag after it cures but by the time I worked the screws this way and that even just a quarter turn about half a dozen times that the thread locking and the drag I wanted was all gone.

    The screws are cocking back and forth along the axis of the gib strip, not falling in then pushing out as I suspect you think they are doing and like I'd suspect if the screw was bent. And they don't move with each turn of the hand wheel. Instead each change where the screw moves is at the end of the travel where I reverse it and the grab against the gib causes it to kick a little axially along the dovetail. And that's when the screws nod the other direction as their ends are pulled along by the gib.

    So I don't think the screw is bent. But it's certainly worth a check. Something may have bounced off the ball handle at some point over the years. I'll let you know once I get back over there again. The poor bloke still works for a living and has a hellish commute so he doesn't get a whole lot of time to work on the shop during the week.

    I'm also starting to think that it might not be all that bad an idea to drill and run a rigid pin through the casting and into a very close sized blind hole in the gib's back face to pin it against this shifting with each travel reversal.

  10. #20
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    Jan 2014
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    As I showed in post #5, my Atlas uses jam nuts. I've had no instances of them loosening up.

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