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  • Colchester tailstock problem

    I bought an old Colchester student lathe a few weeks back. Got it powered up and ordered a quick change toolpost and a drill chuck for the tailstock. I did my first turning with it today and it worked well until I went to drill a hole in the bushing I was machineing. When I brought the center drill up to the workpiece it was obvious by eye that the drill was below center. Took the tailstock off and flipped it over. There I can see considerable wear on the tailstock. I didn't think to check for that when I bought the machine. Any suggestions on how to fix this?

  • #2
    How far below center was the drill point?? Approx. Adjusment in and out is easy, up and down requires shimming between the tail stock base plates. I just went through this a few weeks ago, go back and look up my posts. Depending on how far off you are I had some success in popping the chuck off the taper and rotating it 120 degrees putting it back on and checking it. I was able to note .003 just by doing that. Playing around like that may help solve some of your problem.

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

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    • #3
      Just looking at it by eye I bet its 1/16 low maybe. I will go back and look for your prior posts. I was considering shims between the base plate but thought I should check here first.

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      • #4
        Wow.... 1/6" low, something isn't right. It doesn't sound like wear. I can't imagine any bedways with that much of a hollow in them. I have seen really bad chucks that will clamp up on a drill bit off center. I would start at the beginning and look for the least likley.

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

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        • #5
          I would also check under the tailstock to make sure there are no chips stuck under the rear of it tilting the front down. The back of tailstocks usually don't have felt wipes.

          JHL..................

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          • #6
            Check from post #223 on.
            http://www.practicalmachinist.com/vb...13/index6.html
            Harry

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            • #7
              Originally posted by beckley23
              Thats a brilliant writeup
              John

              I used to be indecisive. Now I'm not so sure , but I'm not a complete idiot - some bits are still missing

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              • #8
                Originally posted by JoeLee
                I would also check under the tailstock to make sure there are no chips stuck under the rear of it tilting the front down. The back of tailstocks usually don't have felt wipes.

                JHL..................
                And if no chips, pull it apart from its baseplate to insure no chips got traped in there last time I was pulled apart.
                Play Brutal Nature, Black Moons free to play highly realistic voxel sandbox game.

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                • #9
                  I fixed my chipmaster by shimming between the tailstock base (only by about 0.010 in my case) to get the barrel parallel to the bed. Then I made an eccentric morse taper sleeve from No 3 to No 2 ( about 0.015 ecc.) which I could rotate to get dead on centre height then lock in position. The horizontal centreing can then be set using the tailstock horizontal adjustment. This also suited me because I wanted a No 2 MT at the tailstock to suit the chucks etc I already had.


                  ALAN

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                  • #10
                    Doug,

                    A Joe says, 1/16" is an *awful* lot of wear - the tailstock runs on different vees & flats than the saddle, so the saddle wearing the bed at the head end would have no effect. If the tailstock has had that much pushing back & forth, then most likely the barrel rattles in the casting - does it?

                    Try running a dial gauge around the inside lip of the tailstock barrel taper, with the barrel fully in and then fully out. This'll tell you if the barrel is indeed out of alignment, and if it's parallel to the bed.

                    If it's parallel but low, then make a shim. It could always be a tailstock from a diffreent lathe...

                    Ian
                    All of the gear, no idea...

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                    • #11
                      I've seen large errors when the tailstock from another lathe has been swapped in, or an unmatched base and top have been put together.
                      Paul Compton
                      www.morini-mania.co.uk
                      http://www.youtube.com/user/EVguru

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                      • #12
                        Originally posted by EVguru
                        I've seen large errors when the tailstock from another lathe has been swapped in, or an unmatched base and top have been put together.
                        Bingo, it is probably switched out from another lathe if it is that low.

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                        • #13
                          Could be the victim of the 'lathe parting out' bandits.
                          Krutch


                          Mentally confused and prone to wandering!

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                          • #14
                            Could be a tailstock from another machine but it does look like the bottom is worn considerably. I wanted to get some photos today and show how far out the TS is but my customers with broken machines keep getting in the way. I will try again on thursday or friday.

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                            • #15
                              The way tailstocks wear can greatly exagerate the measured drop. IME, they will generally point down and to the front, and you are measuring at the tip of a center, most likely with the spindle extended. So your 1/16" drop may only be a few thousandths at the TS bottom. The point of the whole exercise I went through on the "Wreck" was to correct that problem.
                              As an aside, that TS in the "Wreck" is from 2 machines. The bottom is original, but the top came from another EE of a smaller swing(Monarch changed the center height from 12" to 12-1/2" when they switched to different style QC gearbox, and the only change in the TS was a taller bottom). To complicate matters, that bottom, as finished, is not parallel left to right, it's about .003" lower on the right, but the spindle is parallel horizontally and vertically to the bed.
                              There's a lot to getting a TS correctly aligned, but it's worth it, in the long run.
                              Harry

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