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  1. #1
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    Default Vice restoration

    Hi all .. I need to reproduce this nut for a vintage vice I am working on.. thread diameter is 7/8" or 22.2 mm.. pitch is just over 4 turns to the inch..
    a couple of questions,.. because of the mystery number of turns.. how would you set up your lathe to cut this thread ?
    secondly... as it is brass, would it be possible to cast the nut around the screw, using the screw as a mandrel ??
    Like all projects, is it going to be worth the effort in the long run..
    Ken.
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  2. #2
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    I would say it will absolutely be 4 TPI, it'll just be wear making it hard to tell. Is it a square form or ACME? Screw cutting without knowing the exact pitch is impossible.

    Sent from my Nokia 8 Sirocco using Tapatalk

  3. #3
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    Quote Originally Posted by caskwarrior View Post
    I would say it will absolutely be 4 TPI, it'll just be wear making it hard to tell. Is it a square form or ACME? Screw cutting without knowing the exact pitch is impossible.

    Sent from my Nokia 8 Sirocco using Tapatalk
    Square form.. i would have assumed 4 TPI also... but no matter how, or where I measure on the screw.. 4 turns = 23.7 mm
    working from a comparatively unworn section, the grooves are 3.2mm and lands are 2.7mm

    Ken

  4. #4
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    I think you have a 4tpi thread where someone has messed up or the machine was totally worn that made it, what brand is the vice? I'd probably just make a new screw and nut, screw cutting that pitch will be hard.

    Sent from my Nokia 8 Sirocco using Tapatalk

  5. #5
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    Default

    Quote Originally Posted by caskwarrior View Post
    I screw cutting that pitch will be hard.
    But not impossible. There probably a good chance the spindle is not worn much, with most of the wear in the nut. I'd be making a nut to fit the existing spindle.
    peter

  6. #6
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    Rather than trying to make sense out of the nut, measure the very end of the thread. Usually that will be the least worn bit and give you the best idea.
    Casting around the screw is unlikely to work well. A nut that size will single point quite nicely.

    Added: just looked at my lathe thread chart. It has 4 1/2 and 4 3/4 listed too - would one of those fit better?

    Michael

  7. #7
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    Default

    or count the thread/turn over 2->3", even 4" that will give better accuracy?

  8. #8
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    Default

    Quote Originally Posted by Michael G View Post
    Rather than trying to make sense out of the nut, measure the very end of the thread. Usually that will be the least worn bit and give you the best idea.
    Casting around the screw is unlikely to work well. A nut that size will single point quite nicely.

    Added: just looked at my lathe thread chart. It has 4 1/2 and 4 3/4 listed too - would one of those fit better?

    Michael
    Sorry Michael.. took my measurements from an unworn portion of the screw.. diameter ranges from 21.7 - 22.1 ..Vice is unmarked, so could have been made anywhere..could be metric ... in fact 6mm pitch is the closest.

  9. #9
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    Maybe set the screw up in your lathe, set the pitch for 6mm and using a piece of wood or something marked with a square thread profile, see if that 6mm pitch holds all the way along. If you get to the end and the sides of the 'cutter' look to line up (allowing for wear), that might help see whether it is metric.

    Michael

  10. #10
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    Default

    Put the screw in your lathe and set the feed to 4 tpi and your lowest rpm, set a tool up just as a pointer and then run the lathe in the air so to speak, and see if the pointer follows the thread all the way to the end.
    If it does then your first problem is solved.

    cheers, shed

  11. #11
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    Quote Originally Posted by kenny_10 View Post
    Sorry Michael.. took my measurements from an unworn portion of the screw.. diameter ranges from 21.7 - 22.1.
    0.4mm on the diameter - thats bugger all for a vice screw. I'd assume the nominal size at 22.00mm.
    peter

  12. #12
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    I would be very, very surprised if any vice needing a rebuild and sold here was metric. I'd be verging on hat eating territory.

    Sent from my Nokia 8 Sirocco using Tapatalk

  13. #13
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    Count the number of threads over a longer distance on the lead screw, say 150 or 6". If it's 6mm pitch you'll count 25 over the 150mm and imperial 1/4" then the count will be 24 over the 6".

    Which ever one it is won't be easy. You could always make a tap too.

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