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Frozen knee...need help!!!

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  • #16
    Russ-- that is useful info. That smell of Kroil will eventually be the smell of success :-)

    I don't know for sure what you have, but the tapered gibs on my Bridgeport mill have a pocket maybe 3/16" wide milled into the edge. In that rides the wide head of the gib adjustment screw. It is a close fit such that the screw cannot move much either direction without moving the gib with it. Since you cannot turn much before it hangs up, it is likely that this is what you are dealing with. If you turn it until it just stops in the "backing out direction, then you may have a thousandth or two (or maybe more) of slack that you could take out when tapping the gib until it hits the screw head again.

    When it does decide to move, the process will be something like tap just a bit, turn the screw just a bit, tap just a bit more etc. This will only go on for a short while until the tapered gib has moved enough that it is physically loose in two dimensions and then you should be able to back the gib out the rest of the way using the adjustment screw. Just have hold of the knee with a hoist of some sort, because you do not want it supported by the jack screw alone as it could tip and bend or damage the screw and nut. I think you already said you had the jack screw nut loose from its bore so that it can just pull out once the knee moves upward.

    So, for now, you have one thing out of the way...that adjusting screw *can* turn up until it is stopped by the gib...which could have been a big obstacle on something that sat out in the weather.

    good luck
    Paul
    Paul Carpenter
    Mapleton, IL

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    • #17
      Originally posted by x39
      Not to put too fine a point on things, but theoretically.....
      I guess I should have made sure my brain was loaded before shooting my mouth off on this last little pearl of wisdom. I went up to my shop and after some experimentation disproved my own theory. Nevermind.
      Last edited by x39; 05-18-2006, 12:45 PM.

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      • #18
        Thanks Paul. I've resigned myself to the fact that this is just plain going to take time now...for the Kroil to work.
        I sure don't want to break anything on this ol' girl...I'm told that Walmart no longer handles parts for Oesterlein milling machines
        Russ
        I have tools I don't even know I own...

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        • #19
          One other thing I forgot to add was that you may benefit from using a hoist to just take the load off the knee. You need something like this to stabilize it as you try to remove the gib anyway. It will also help by removing to some degree, the normal wedging forces against the gib due to the weight of the knee wanting to pivot out from the column. Before attempting to tap the gib out, removing all other resistance (other than rust) should only help matters. Do not pull up too hard, however or you will be wedging the tapered gib "socket" in the knee into the gib and the dovetail way which may currently be fixed in place by rust. You just want to take the tension off. I had to do this in removing my bridgeport knee from the column and I was not fighting any rust

          paul
          Paul Carpenter
          Mapleton, IL

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          • #20
            I would not try and move it at all.
            take the whole thing off
            undo the Gib's and pull it off
            as there will be rust on the ways underneath ........
            this way.....you get to inspect them and clean them

            do the same for the rest of the machine

            do not try to unstick anything
            dismantling and cleaning is the answer ..

            you are taking short cuts by trying to get things moving

            you are in too much of a hurry

            the machine will need to be stripped any-hows

            please take my advice

            all the best...mark

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            • #21
              Mark-- I think what he is telling us is that he cannot "undo the gibs"

              In order to remove the gib that holds the knee to the column, he has to be able to slide that gib by backing out the adjustment screw and removing it. The gib won't slide yet (even to remove it) and that is what he has to accomplish first.

              You are sure right though that sliding the knee on the ways after getting the knee loose (before removing the rust) would be a bad move.
              Paul
              Paul Carpenter
              Mapleton, IL

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              • #22
                OK then

                Withdraw the knee raising shaft the shaft that the handle goes onto.........there will be probably a set screw in the side that holds it in .
                Take off the table and then the swivelling bit.

                Attach chain blocks to the knee, and take the weight .

                knee raising screw should then screw down.

                Screw it down all the way .....then take off the screw plus its support.

                You are then left with the knee only on the machine.......after pulling gib strip out, the knee should then swing loose....if it don't ...attempt to unbind it by pulling on the chain blocks.

                This is how my similar fritz werner is held together.......yours looks very like it, in construction .

                Hope this helps.

                all the best....mark

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                • #23
                  Mark..Paul is correct. The gib absolutely will not move. And with rusted parts...you HAVE to move something eventually. I'm not being in a hurry(now). The only things I'm moving are the things I can clean, derust and oil beforehand.
                  I don't want to pound on the gib anymore than I have as I fear it wil start peening over.
                  The hydraulic jack I have under the knee puts a whale of a lot more pressure on the knee than a chain hoist would and it won't budge.
                  The DI I have mounted gives me some kind of idea how far I'm going with the jacking.
                  I've probabaly "rocked" the knee a thousand times or more by now and it's still solid.
                  I could get a bigger jack....break some stuff and free it up but I choose not to. This thing is in such good shape...I can be patient. This old iron will fling chips again I promise you that...it just may take awhile.
                  I've owned and built a lot of cool machins over the years but this thing is the neatest machine I've ever had. I'm in love....rust and all
                  Russ
                  I have tools I don't even know I own...

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                  • #24
                    Russ, have you tried using Coca-Cola to eat the rust away? Sounds crazy I know but Coke will do this, and as you're going to take it all apart to rebuild anyway the sticky residue won't be a problem.
                    Regards

                    Peter

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                    • #25
                      Peter...Thanks! Never thought of Coke. I do know it works..I've used it on chrome bumpers. May try it if the Kroil doesn't work.
                      Russ
                      I have tools I don't even know I own...

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                      • #26
                        hydrochloric acid (masonry cleaner its usually about 15 percent acid)

                        that usually dissolves all the rust away and leaves sound metal intact
                        may be enough to break it free.

                        all the best..mark

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                        • #27
                          Here's an old trailor auto brake that I saved a few years ago

                          This is it before





                          And this is it after dabbing it with a paint brush and masonary cleaner for about 2 hours...must be degeased first or the acid won't work
                          must be neutalised with bicarbonate of soda strait after you've finshed ..or will rust overnight ..and keep on rusting.




                          all the best.mark

                          PS ...sorry to hear about your friend Russ
                          Last edited by aboard_epsilon; 05-18-2006, 06:37 PM.

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                          • #28
                            Stop and analize your gib!!!!, depending on design you could be wedging it into the dovetails more by using a jack and trying to lift your knee, Take off both gib screw adjusters and look at the top of the gib and the bottom, if your mill is like mine the top will be thicker --- Using a Jack will do nothing but self wedge the gib even more to the point of breaking your dovetails or distorting your base or knee!!! If anything you need to put more weight on the table, but first, If this is your design GET RID OF THE JACK!!! then build a drive punch that is wide and flat and has enough surface area to cover the wide flat gib end (the thinner gib end which should be at the bottom of your knee),,, and if this thinner gib end is at the bottom of the knee then pound directly up and as you stated before do not peen the gib end over, if this doesnt work put more weight on the table and try it while slightly loading the knee handle in the lowering position (might take two people), I might try an air hammer with a modified bit and put it on a mild setting --- many frequent smaller hits are better than big blows for breaking rusted parts loose, If your gibs are of oposite design than i would indeed use a jack on the knee exceeding all the knee and table weight by a maximum of double, and id try air hammering from the top gib end down but only if its the thinner edge, all gibs are self wedging --- thats why both adjusting screws are so important, one takes up the slack and one keeps the gib from going to far, The latter is actually the most important, if a CNC machine loses the limiter adjuster the table will self jam to the point of destruction of drive components and or dovetails (if equiped without shear pins), good luck, let us know what kind of design you have...

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                            • #29
                              good morning.

                              just thinking about the post directly above, it seems like it would be really hard to adjust a gib from the bottom of a knee. i would be surprised [well, maybe not] if the wide end of the gib was at the bottom.

                              my dad used to use brake fluid at a penetrant. it is pretty hard on the paint, but according to him it worked.

                              personally, i would keep soaking it with kroil and tapping here and there. i have found that it is always better to start with the least invasive plan and then move on to other stuff if that doesn't work.

                              remember that this is a machine tool that you are working on and as such, it should have pretty close tolerances. it doesn't take much rust to lock it up pretty tight.

                              i think i might want to have some lifting type tension on the table and bed. like an engine hoist if it is strong enough. it could get pretty exciting to knock the gib out depending on what is loose from where.

                              good luck.

                              peace.
                              billr
                              ........i dremel. therefore i am..........................

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                              • #30
                                Bill read the post again.
                                He's saying the wide part MAY be to the top and so jacking the knee up will wedge it harder.

                                .
                                .

                                Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.



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