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  • Tight Saddle on Bridgeport

    Hi All,

    As some of you have undoubtedly seen on Practical machinist (applogies if this is blasphemy) i have been having issues with the knee of my bridgeport after it "fell off" the Knee crank screw (you could turn the knee crank and no height change)

    i fixed the problem which involved me stripping down the knee of everything (saddle and table[bed]). I am now at the re-assembly stage of the Mill and have loosened off all of the backlash adjustment screws and gib screws, yet the friction of the table is still abnormally high. (To answer the inevitable question your thinking, the ways are not screwed, the saddle and bed would slide smoothly like glass before this task)

    Has anyone got any ideas how i can reduce the friction? If you need more info to answer, let me know and i will supply it to you

    Thanks in advance,
    Gordo

  • #2
    How far did you loosen the gibs? Try shoving the thing into place and readjusting from there.

    IME--at least on vertical surfaces, horizontal may be a little different--having things too loose can let them tilt and bind.

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    • #3
      This may or may not help, but I had a similar problem on a lathe cross slide - simply couldn't figure out what had made it harder to turn. I finally found where I had made a VERY small ding on the brass half nut while reassembling. I took it to the mill and faced it a few thou, and things are back to normal.
      HTH,
      Greg

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      • #4
        If you've run the knee off the end of its leadscrew, then I think there's every chance that you've distorted the end of the nut.
        Paul Compton
        www.morini-mania.co.uk
        http://www.youtube.com/user/EVguru

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        • #5
          I farted around for hours on mine ..

          that is the lead screw ..NOT THE GIBS

          You can have it loose on the nuts ..but when you tighten the bolts holding the dial on ..it keeps on going tight ..

          i cant remember what i did in the end..it was years ago ..but involved a lot of guess work ...taking the four bolts out, AND dial off and starting over several times.

          all the best.markj

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          • #6
            BTW ..How do you pronounce gibs

            is it jibs .
            .or as in Bee Gee's gibs

            all the best.markj

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            • #7
              Mark I was always told it was pronounced the same way as gill as in fluid measure and not gill as in fishes respiratory apparatus. If that makes sense!

              Alan
              West Sussex UK

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              • #8
                A jib is a sail.
                It's only ink and paper

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                • #9
                  Gordo, have you tried the saddle without the feed screw in place and adjusted the gib as you slide the saddle back and forth by hand with the ways oiled. I assume your doing the saddle first and then the table.
                  It's only ink and paper

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                  • #10
                    Originally posted by Carld
                    A jib is a sail.
                    A jib is the top extension boom of a crane.

                    JL.......................

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                    • #11
                      Well, I'm looking at my Webster's now. Looks like I've been in error all my life.

                      According to my dictionary, the "g" in the words 'Giant' and 'Gibberish' is pronounced as "ji...", but the "g" in 'Gib' (the machine tool part) is pronounced like the g in 'Ghost'.

                      I'll probably remember that for about 3 or 5 days, then revert back to my old habit.
                      Lynn (Huntsville, AL)

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                      • #12
                        Originally posted by aboard_epsilon
                        BTW ..How do you pronounce gibs

                        is it jibs .
                        .or as in Bee Gee's gibs

                        all the best.markj

                        loke andy gibb

                        hard G

                        At least in this part of the rustbelt.

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                        • #13
                          Ok, so after three hours of fiddling, i have the gib adjusted to a point where the saddle glides as smooth as it did previously.

                          the Screw seems to have MORE than enough play in it (Considering i can feel the amount of play within the backlash adjustment) - im worried about backing off the adjustment screw further in case i cause myself other issues.

                          The knee screw is fine now, and works perfectly (thankfully)

                          PS: i do believe "gib" is pronounced as it sounds (similar to 'gibson') not Jib as in the sailing term

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                          • #14
                            Originally posted by Alan Smith
                            Mark I was always told it was pronounced the same way as gill as in fluid measure and not gill as in fishes respiratory apparatus. If that makes sense!

                            Alan
                            yeah, but i don't know how to pronounce gill either ...so not making sense lol

                            Funny, it's not in the Oxford online dictionary or the Cambridge online dictionary or the Longman online dictionary ...not as gib or gibb ..word not recognized ..Oxford only list it as short for Gibraltar

                            all the best.markj

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                            • #15
                              Getting back to the Point. I now only have a tight leadscrew

                              :P

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