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Yet Another Enco Mill/drill Question

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  • Yet Another Enco Mill/drill Question

    So while we seem to be on the subject, I've got a mill/drill from Enco, about 25 years old, model 91000.
    I've always had a minor problem keeping one of the gibs adjusted, so this morning I pulled it out and lo and behold, I think it's the wrong one for the unit. It appears to have been broken off at the back side to make it the right length. ( like someone needed a new gib and grabbed one and snapped it to length) It is very hard to adjust as it seems too loose or too tight.
    Is it possible that gibs come in different tapers?
    If so this might explain why it is difficult to move the table when the adjustment seems to be in the right place, and when adjusted so that the handle turns free enough to not make my arm ache, there is some play in the table.
    I know this sounds like a really dumb question, but sometimes a dumb question is what it takes to yield a really good answer. Any help or insight to this would be appreciated.
    where does one find gibs anyway?
    grumpy old fart

  • #2
    Originally posted by wirewrkr
    where does one find gibs anyway?
    Inside of a piece of suitable stock............

    A tapered gib that has adjustment at one end only might actually be tight in one direction and loose in the other. If there is play in the adjustment, that *could* happen.

    One way the friction pushes the taper in the direction to loosen it. The other way, it tends to grab like a chinese monkey puzzle, as the movement wedges the gib in more. The total motion need not be much, depending on lube, taper of the gib, condition of ways, etc. With an adjusting screw both ends, the gib can be trapped to prevent movement.

    However a shallow taper has to move a long way lengthwise to take up much distance sideways, so it shouldn't be an issue.

    But maybe there is a second broken piece in there floating around unrestrained...... That would make one way tend to tighten, and the other be looser.
    CNC machines only go through the motions


    • #3
      No, there's no second piece in there, it's only about 8" or so.
      grumpy old fart


      • #4
        To answer your first question, yes -- tapered gibs come in many different tapers. Is the taper you're having problems with on the y-axis? If so, is it possible that someone got an extra x-axis gib and snapped it to length (shudder!)?

        The other thing to check, like JT mentions, is the slack in the slot for the adjusting screw. On mine, it was very loose, so the gib would slide in and out as you cranked the leadscrew. A lot of folks will either make a gib adjusting screw with a fatter head, or fill in the slot in the gib so there's less play.

        If you have to make a new gib, you're in for an experience The gibs on the mill/drills are cast iron, so I would start with a slice of cast iron as close to the dimensions of the axis you're trying to fix...
        "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."


        • #5
          alternate error source

          I too have a jib that moves just enough to cause slop in one direction of table feed and binding in the other. I made a double ended lock to stop this motion and it helps but is not solid enough. It is on my list to improve.

          I had another problem that caused binding and it was aggravated by me tightening the split nut holder. Note that the lead screw is fixed in position relative to the mill at the left end by a bearing. It is then fixed in position at the right end. A straight line is defined by two points so this is all fine. But then we have the split nut in the middle. IF it was a tight fit, you would be trying to define that line with 3 points and it can't be done unless you had perfect alignment. That is why they make the split nut a loose fit. Mine was a loose fit but not loose enough. I would get binding as I moved the table to its left or right extreme.

          My solution was to move the table to the right, loosen the left bearing support, and let it find its own best position. I then drilled and tapped new holes and locked it in place. Did the same on the other end. That helped a lot.
          Rick Sparber

          [email protected]
          web site:


          • #6
            Ah HAH!
            There is a lot of slop in the jib screw, obviously because it's not the original correct one.
            Tonight I'll either build a new screw or more likely shim the original.
            thanks, we'll see if that fixes it.
            grumpy old fart