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Thread: South Bend 9 owners, a question please?

  1. #21
    Join Date
    Jan 2016
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    what i did with my cross slide was to lap it basically. i ground about 15 divots per square inch on the flat surfaces of the dovetail in the cross slide, removed the nut, lubricated the whole thing with heating oil (diesel), and scraped the flat on the carriage until the cross slide was evenly snug across the entire travel. it doesn't take that much time to do this, when you snug the gib screws and move the cross slide back and forth, where it gets stiff the oil film breaks down and it polishes the apron (don't touch the cross slide after flattening it on the surface plate) just scrape down the shiny spots.

    as such the gib screws can be set finger tight with a small screw driver and they won't move on you because they are always applying pressure to the gib. the divots in the cross slide help a lot to retain oil and lubricate it.


    you could replace them with nylon locking ball plunger setscrews. the spring will always keep pressure on the gib, perhaps enough that you won't need to actually tighten them unless you need to lock it for taking a heavy cut when boring (with the tool hanging over the left side, pulling up on the side with the gib)

    https://catalog.monroeengineering.co...pring-plungers
    Last edited by johansen; 01-10-2019 at 01:38 AM.

  2. #22
    Join Date
    Jan 2004
    Location
    Missouri
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    30,099

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    Vibra-tite is a drag increaser, and NOT a threadlocking "glue" like Loctite. It works rather well, very much like the screws with the blue patch on the threads. The threads you put it on should be clean, but if the mating threads are oily, that makes hardly any difference.

    As for the gib loosening the screws, that is one reason for milling "screw pockets" into the gib. Without the pockets, the contact with the screw is off-center and movement applies a torque. WITH the pockets, the end of the screw is the contact point, and there s little to no torque form any possible movement.

    At first glance, I do not see any particular case for a bent feedscrew causing the loosening issue.

    As for locking nuts, they have a problem.... They tend to pull the screw n the direction to loosen the gib. So you have to over-tighten, and then use the locking nut to slightly loosen the gib as you tighten the nut. It's a fine balance you have to find.

    Taper gibs are much better.
    1601

    Keep eye on ball.
    Hashim Khan

  3. #23
    Join Date
    Dec 2015
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    Chilliwack, BC, Canada
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    Part of the problem as I saw it on the compound is that the there are the proper angled screw pockets but they are larger than they should be to hold the screws. That may be part of it. Or it may be simply that the holes in the slide casting are a bit worn with time. Either way I watched the screws walking in their holes with each reversal of the hand wheel.

    I need to order a bucket worth of stuff online in the next couple of days. Already started in fact. I'll find some Vibra-Tite to add to the list. And thanks for describing how it works. Sounds like just the thing I've been after for some time now.

    I used to do enough manually adjusted valves on cars and bikes. So working a wrench on the lock nut and driver or allen key on the screw is an old and honed skill. Which is why I had suggested it to him as a solution.

    I'm rather keen to try that Vibra-tite now...

  4. #24
    Join Date
    Aug 2011
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    Central Virginia, USA
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    If you see the screws moving, I am inclined to think someone has changed the screws or holes in some way. SB used #12-28 screws I think, perhaps you should check if that is still the case. Also, I am inclined to agree with the suggestion of adding locating pins to the gibs, the screw divots alone are not enough to truly constrain the gib. Smart and Brown used that technique in their SB clone, I think.

    allan

  5. #25
    Join Date
    Aug 2012
    Location
    Warwickshire, UK
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    Quote Originally Posted by BCRider View Post
    Part of the problem as I saw it on the compound is that the there are the proper angled screw pockets but they are larger than they should be to hold the screws. That may be part of it. Or it may be simply that the holes in the slide casting are a bit worn with time. Either way I watched the screws walking in their holes with each reversal of the hand wheel.

    I need to order a bucket worth of stuff online in the next couple of days. Already started in fact. I'll find some Vibra-Tite to add to the list. And thanks for describing how it works. Sounds like just the thing I've been after for some time now.

    I used to do enough manually adjusted valves on cars and bikes. So working a wrench on the lock nut and driver or allen key on the screw is an old and honed skill. Which is why I had suggested it to him as a solution.

    I'm rather keen to try that Vibra-tite now...
    Those pointed end grubscrews fitting into drilled holes in the gib are prone to jiggling around when the lathe is no longer young, and maybe the screws are replacements for the factory originals. My first thought would be to fit longer allen screws with locknuts, and maybe drill an extra one for a tee headed screw to act as a slide lock whenever you need it. Really though, and it itsn't much effort while you are working on the machine, the best solution is to dowel the gib to the slide. Simply fit the gib in place, clamp it, making sure all the grub screws are locating in their dimples, then drill through the slide and gib at each end, 1/8" dia, and fit an 1/8" dia silver steel (drill rod) dowel. Chamfer the end so it doesn't drag a groove in the side of the other part of the slide. This effectively stops the gib from being able to move longitudinally. Well worth doing.
    'It may not always be the best policy to do what is best technically, but those responsible for policy can never form a right judgement without knowledge of what is right technically' - 'Dutch' Kindelberger

  6. #26
    Join Date
    Apr 2017
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    Kelowna BC
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    When I used my Southbend, its been a while.
    I liked to keep a small screwdriver by the lathe.
    When I wanted rigidity I nipped up the screws, when I needed to feed withbthe topside I slack them a bit. Take a few seconds..
    Just like a boring head, I adjustvthem for what I need and am doing.
    Personally I think the lathe looks a lot better without cobby looking nuts hanging out the side.

  7. #27
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    Aug 2012
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    Warwickshire, UK
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    Quote Originally Posted by 754 View Post
    When I used my Southbend, its been a while.
    I liked to keep a small screwdriver by the lathe.
    When I wanted rigidity I nipped up the screws, when I needed to feed withbthe topside I slack them a bit. Take a few seconds..
    Just like a boring head, I adjustvthem for what I need and am doing.
    Personally I think the lathe looks a lot better without cobby looking nuts hanging out the side.
    Needn't be cobby looking. They are only lock nuts, so thin down standard nuts to half thickness.

    Anyway, I'm more interested in my lathe working properly than it being a concours queen.
    'It may not always be the best policy to do what is best technically, but those responsible for policy can never form a right judgement without knowledge of what is right technically' - 'Dutch' Kindelberger

  8. #28
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    Dec 2015
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    Richard, you've echo'ed my thoughts perfectly. From the locknuts to the anti walking pin. And I like your ideas of halving the nut thickness and adding a locking screw. Suitably sized these extras need not stick out and snag stuff at all.

    Could this be another case of "great minds think alike"? .... and never mind the rabble that comes back with the other half of that....

  9. #29
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    They need not stick out far I am familiar with jam nuts.
    But first off , not sure if it is a real problem... or the the lathe just needs cleaning and adjusting.
    But if you are ok with the t opslide looking like a Harbor Freight X Y drill table...by all means do it..

  10. #30
    Join Date
    Jan 2004
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    Missouri
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    Why bother when the Vibratite does it just as well?
    1601

    Keep eye on ball.
    Hashim Khan

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