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Table twists during moving of the saddle and or pulling on table extremes.

Discussion in 'BRIDGEPORT MACHINES INC. & B'PORT CLONES' started by expressline99, Aug 3, 2017.

  1. expressline99

    expressline99 H-M Supporter - Premium Content H-M Supporter-Premium

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    So my table has a twisting action that can be repeated by moving the saddle in and out. If I lock the saddle there is no movement. This can also be repeated by pushing and pulling on opposite ends of the table. This is to the point of hearing it "click" as it hits the range of "twist". I have adjusted the gib all the way in that makes Zero difference. As well, Moving the saddle all the way in towards the column doesn't change it...or all the way out away from the column.

    To me this seems like a completely worn out gib. But maybe I'm not thinking about it correctly?

    How should I approach this?

    Paul
     
  2. dlane

    dlane Active User H-M Supporter-Premium

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    what is it ?
     
  3. expressline99

    expressline99 H-M Supporter - Premium Content H-M Supporter-Premium

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    Bridgeport Series 1 variable speed 2hp
     
  4. higgite

    higgite General Manger - Proofreading Dept. Active Member

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    Does the saddle not get harder or easier to move when you adjust the gib?

    Tom
     
  5. expressline99

    expressline99 H-M Supporter - Premium Content H-M Supporter-Premium

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    It doesn't get harder....
     
  6. RJSakowski

    RJSakowski H-M Supporter - Premium Content H-M Supporter-Premium

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    A dumb question but are you sure that you are adjusting in the right direction? (Not as dumb as it sounds. Two years ago, during a maintenance smeinar at the Tormach open house, the presenter had it backwards. It took a photograph to convince him and they subsequently corrected the user manual.)
     
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  7. expressline99

    expressline99 H-M Supporter - Premium Content H-M Supporter-Premium

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    Not a dumb question at all. I'm doing righty-tighty and it comes out if I lefty-loosey. I pulled the gib out a few minutes ago and it's worn on the ends not in the middle. The middle still shows scraping marks. But the wear is only about .005 off of the Ridge left behind that didn't wear. Hopefully the saddle ways aren't so shot I can't get rid of that. I should probably order some gauge pins large enough to measure that....
     
  8. RandyM

    RandyM United States Global Moderator Staff Member H-M Supporter-Premium

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    Can you try adding shims behind the gib?
     
  9. 4gsr

    4gsr Global Moderator Staff Member H-M Supporter-Premium

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    The clicking noise you are hearing is probably the gib riding up and catching on the .005" ridge and popping back in place. Take the gib and file down this ridge flush with the rest of the gib. Then take a oil stone and hone the surface slightly to make sure you removed all the of the ridge. Re-install and see if the clicking noise goes away.

    I'm very sure you have lots of wear in the slide, but let's take it one step at a time. Also, are the ways on the cross slide of your knee chrome plated? of just bare iron?

    The gib is purposely scraped out in the middle so it bears on the ends. This is the proper way to final fit a gib once it is scraped and fitted at the factory. It will be likewise on the saddle ways, too.
     
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  10. expressline99

    expressline99 H-M Supporter - Premium Content H-M Supporter-Premium

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    The ways are just bare iron. Not chromed. I'll work on that ridge and report back.
     
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  11. expressline99

    expressline99 H-M Supporter - Premium Content H-M Supporter-Premium

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    I filed down the ridge and there is still some shimmy during pulling the outer edge of the table or moving the saddle in and out. It does "seem" that the table is square to the knee when bringing the saddle towards the operator. When it twists the other way the gib side of the saddle moves last...if that is the right way to say it. This is with the gib screw tightened all the way. So no more adjustment.

    Ok it's .007 of movement right at the gib as I pull on the far right side of the table. This is relative to the saddle ways where the indicator was setup. As well to set it to zero I pushed on the far right of the table set the indicator then pulled. This appears to be a bit better. But it should be tight. Would a new gib take care of this? I maybe taking the table off this weekend to inspect.

    Paul
     
    Last edited: Aug 4, 2017
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  12. Ulma Doctor

    Ulma Doctor Infinitely Curious Active Member

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    you may have a wear pattern deep in the table dovetail.
    the gibs are tapered and if you have run out of gib adjustment, you have some wear present.
    a new gib could be a temporary solution, i suppose some well placed shimstock could take up some clearance too.
    unfortunately, you may find that there are other components in the table assembly and screws that may also need attention.
    you'll need to decide whether you want to go down the rabbit hole (with me :bang head:) or let it ride with minimal restorative consideration.
    i'd also suggest adjusting/tightening/locking all the gibs to reduce observed deflection, you can get false readings if there is clearance in the other gibs
     
  13. 4gsr

    4gsr Global Moderator Staff Member H-M Supporter-Premium

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    Paul,

    Since you are the new owner of a "rock", take that gib, worn side down, and lay it on top of your surface plate and see if it "spins like a top" I don't mean spin it but rotate it and see if it hinges in the middle. And I suspect it will. Next take some feeler gages and or some shim stock, and shim up until it stops rotating. This will give you an idea of how much wear there is with the gib. I believe you mentioned earlier that the gib was hollowed out in the middle? It may be worn so much that the middle is now the bearing surface of the way.
    The key to this exercise is to identify what to rework first. Sounds like the gib could be a starting place. Don't waste money on buying a new gib, you won't gain nothing but a new gib that still needs scraping and fitting. We'll help you on shimming up the gib once you work on getting it running straight.
    This will be a good time to start you learning on scraping on a gib to get you a better fit.
     
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  14. expressline99

    expressline99 H-M Supporter - Premium Content H-M Supporter-Premium

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    Oh I'm headlong into the rabbit hole already! I had planned to replace the nuts and screws and bearings. The rabbit hole on the rebuild head was so deep I don't know how much I spent. Oh and DRO once everything is mechanically fit.




    The gib still had scraping marks on the center but not on either end. But I will check it out either way.
     
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  15. expressline99

    expressline99 H-M Supporter - Premium Content H-M Supporter-Premium

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    OK the gib pivots on both far ends if you have the side that faces the center of the machine down....so you turn the right side it pivots on the far left and vise versa.
    If you flip the gib over it pivots 40% in from the thinnest end.
     
  16. expressline99

    expressline99 H-M Supporter - Premium Content H-M Supporter-Premium

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    I had missed the shimming part of what I was supposed to do.

    So with the side of the gib that normally faces the center of the ways...face down on the stone. The center is high and I can get a .003 shim under it with it barely catching. Once I put the .003 under it I can hinge it anywhere I move the shim.

    If I flip the part over the most tapered end is high for about 30 to 40% of the length. I can get a .005 under it. That side hinges pretty much dead center.
     
  17. expressline99

    expressline99 H-M Supporter - Premium Content H-M Supporter-Premium

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    I guess at this point I might be to where working on the gib may not help. Before I get some practice on some straight edge scraping first. I am however, thinking this week I'll get a solid cart built to move the table over on to and get to work on the screws/nuts and cleaning. No matter what I do I have to get those things fixed plus get the oiler ports cleaned on working again....and some new way wipers.
     
  18. expressline99

    expressline99 H-M Supporter - Premium Content H-M Supporter-Premium

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