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Discussion in 'Off-Topic' started by Keith Robinson, Dec 1, 2014.

  1. Keith Robinson

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    Nov 30, 2014
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    been trying all over the world (well ebay at least) to get some 3/32" whitworth screws for a pair of synchro receivers. Lots of suppliers say there's no such thing and the rest don't have anything. Could anyone help please? I do know that the size exists because you can buy a tap and die in 3/32" BSW. And I have some already in the synchro connections UNC is close but won't go in, can't tap the connectors as the e got fine brushes attached. They're 2.4mm outside dia 48 TPI about 12mm long pan heads
     
  2. WBahn

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  3. Keith Robinson

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  4. jpanhalt

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    If that fails, what size and pitch do you need? I have a very nice Smart and Brown lathe from 1965-1966 that is all Whitworth. I bought a bunch of spares awhile back (1980's) and will try to locate the source if that other lead fails. Outside diameter and pitch will be sufficient. Do they have hex heads or slotted cheese heads like in your gyro?

    John

    Oops. Just read your post #1. I will look into it further. John

    Edit#2: Some microscope threads are still Whitworth, because of the greater grip of 55° vs. 60° with fine pitches. You might consider contacting a microscope dealer.
     
    Last edited: Dec 1, 2014
  5. Dr.killjoy

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  6. Keith Robinson

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    Nov 30, 2014
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    I tried Namrick and they dont have any and cant source them anymore. at least it confims that it is a valid size. Microscope dealer is good info. Ill give it a try. the screws are for a Synchro Reciever for the electical connections. THe ones in the gyro are all BA. thanks again for your help. regards Keith
     
  7. jpanhalt

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    BTW, the screw heads you show are probably called cheese head.
    upload_2014-12-2_11-19-29.png

    Pan head is flatter and more rounded. Fillister is very similar, but often is more rounded (http://www.mcmaster.com/#machine-screws/=uulbm2 ).

    That distinction isn't going to help you find an exact replacement. The question is whether you want an exact replacement for a true restoration or something that looks about right but is not really a Whitworth?

    For the former, you will probably end up making it. If you can get a 3-48 NC cheese head screw, you might be able to chase it with the Whitworth die to get a fit. However, there will be several threads near the head that the die won't fully reach. You could fix those or do the whole treading with a small lathe.

    If your choice is the latter, an alternative would be to drill the hole to the minor diameter of a 3-48 NC, then run a tap down it and use a 3-48 NC screw.

    I could not find the source of the Whitworth screws I got for my lathe. It likely it was a British car parts dealer. Sorry, I can't be much help.

    John
     
  8. studiot

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  9. Keith Robinson

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    Nov 30, 2014
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    Thanks for this info, John. the heads are not that important its only to get it wired up, not for restoration. unfortunatley I cant drill out the holes as the connectors are also super fine brushes that go down into the motor windings.
    so im only left with the screw option. I will probably try to make some by tapping some slightly larger ones down. I have literally tens of thousands of screws gathered over umpteen years, and not one will fit these! could you credit it?
    youve been a great help - thanks. Keith
     
  10. Keith Robinson

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  11. studiot

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  12. Keith Robinson

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    No I have some BSF and they are finer threads and slightly larger. any material would do (metal!) even unobtainium as long as its not too expensive length is about 12mm, although obviously I could nib some off longer ones
     
  13. studiot

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  14. Keith Robinson

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    Nov 30, 2014
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    Cottingham East Yorkshire
     
  15. Keith Robinson

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  16. studiot

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    You'll be an expert by number 10 then.

    :)-
     
  17. Keith Robinson

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    Nov 30, 2014
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    probably just have sore fingers! :(
     
  18. GopherT

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    Sore fingers is one reason why God created vises and tapping wrenches and ...
     
  19. studiot

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    I thought apprentices was the reason why God created vises and tapping wrenches.

    :)-
     
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  20. Keith Robinson

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    Nov 30, 2014
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    Used fingers on first one because I was in the warmth of my mancave in the sky. Will now venture outside to icy workshop to retrieve mechanical assistance aka die stock vice,oil etc. (well, after breakfast maybe!)
     
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