Colchester worn cross slide nut

  1. fizzy Member

    Messages:
    6,374
    uk
    Good point hadn't thought of that!
    He does say in his ads though that this is the last batch for quite some time.
    I have noticed RDG tools sell ACME taps of the right size.
    Looks fairly easy to make.
     
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  2. ronan

    ronan Member

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    9,926
    dublin
    Be careful of rdg, they do sell a lot of far eastern tat. When something goes sour, they won't repair or give you your money back.
     
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  3. minimutly Member

    Messages:
    1,229
    Location:
    Pembrokeshire Wales
    I tried uploading a video of mine, but file too large. Anyway, it moves in and out if you push and pull it.
    And I measured it on the feed screw, 45thou. The screw (and dial) has very little slop in the spindl/bush. So I'm not worried in the least. Is yours like this @fizzy?
     
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  4. Seadog

    Seadog Forum Supporter

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    NE London - UK

    Upload to YouTube and post the link.
     
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  5. Agroshield Member

    Messages:
    946
    You will have great difficulty pushing a single tap through to form an ACME thread. At the least, you will need a set of taps.

    What is the size and pitch of the thread? How many graduations on the handwheel? I ask because on some Colchesters (Bantam, Chipmaster), the cross-slide screw is two-start.
     
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  6. hermetic

    hermetic Member

    Messages:
    140
    Yorkshire UK
    If you can get a new nut, and the thread is worn, if you know someone else with a lathe, you can cut off the thread, then bore remainder of the shaft, and turn down a piece of acme threaded rod to fit into the bore and secure with a couple of roll pins at 90deg to each other. I filed up a bronze nut, and took my old thread to a local engineering company, and they bored and threaded the nut, and fitted a length of new acme thread to the original splined part of the cross slide shaft. This was actually on the DS&G that is in the pic to the left of this post
    Phil
     
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  7. fizzy Member

    Messages:
    6,374
    uk
    There appears to be very little wear on the thread. Even the nut isn't that bad I am sure but it bothers me.
    There is no wear or slop on the thrust surfaces - silky smooth.

    Will post piccies in a second.

    5tpi thread - handwheel graduated 0 to 190 to 0
     
  8. fizzy Member

    Messages:
    6,374
    uk
    cross1.jpg cross2.jpg cross3.jpg
     
  9. ronan

    ronan Member

    Messages:
    9,926
    dublin
    Have you measured the backlash with a dti or anything ?
     
  10. Seadog

    Seadog Forum Supporter

    Messages:
    6,470
    Location:
    NE London - UK
    It's difficult to tell from a photograph, but to me that looks to have the classic waisted wear pattern. Worn in the middle, unworn at the ends.
     
  11. fizzy Member

    Messages:
    6,374
    uk
    I used a drill shank in the thread and a micrometer. Hardly any difference anywhere.
    The nut doesn't seem any tighter or looser anywhere either.
    Yes very hard from photos I should have cleaned it better.
     
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  12. Pete.

    Pete. Member

    Messages:
    9,427
    Location:
    Kent, UK
    Not much wrong with that screw. It's got some wear but most are much worse. Appears to be single-start. Some colchesters are 2-start.

    Is the telescoping section firmly held inside the splined hole?
     
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  13. fizzy Member

    Messages:
    6,374
    uk
    I haven't tried to remove it - should it come out easily? And do I need to free it up?
     
  14. minimutly Member

    Messages:
    1,229
    Location:
    Pembrokeshire Wales
    Fizzy, put it back together and use it, your lathe is old, a little worn, but it will do anything you want of it. A little backlash never harmed any job.
     
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  15. fizzy Member

    Messages:
    6,374
    uk
    Lol you are probably right!
    I am really astonished just how good the crosslide is - it is silky smooth to move by hand without the nut attached - no play at all anywhere across the full travel.
    I bought the lathe off a retired toolmaker - he obviously knew what he was doing when he chose the machine.
    I have ordered a replacement nut - if it removes that little bit of play I will be happy.
    Lathe is turning a taper though - I suspect the headstock needs alignment - that should be fun. Before I do that though I need to fit the gap back in accurately.
     
  16. minimutly Member

    Messages:
    1,229
    Location:
    Pembrokeshire Wales
    Setting the toolpost shouldn't take more than half an hour if you have some parallel stock lying around.
     
  17. fizzy Member

    Messages:
    6,374
    uk
    No the headstock!
     
  18. fizzy Member

    Messages:
    6,374
    uk
    Sorry missed this - yes sounds the same.
    My chatter and bad finish might be down to the Jacobs rubberflex collets - or me - don't remember a problem with the 4 jaw.
    Don't really want to disturb it as I spent ages getting it to run true.
    I now have a 3 jaw so will try that.
     
  19. minimutly Member

    Messages:
    1,229
    Location:
    Pembrokeshire Wales
    Sorry meant the tailstock.....
     
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  20. hermetic

    hermetic Member

    Messages:
    140
    Yorkshire UK
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