Very small machine screws

Discussion in 'Fettling Forum' started by ColinG, Jun 4, 2021.

  1. ColinG

    ColinG United Kingdom Subscriber

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    I found this tiny pot of machine screws in a junk shop. They are absolutely tiny but I wasn't sure what thread they are but I had an inkling they might be BA so I checked them with my BA tap and die set and they're 10BA!!!

    IMG_20210604_193907_9.jpg

    IMG_20210604_193919_7.jpg

    I was looking to maybe use one to replace the screw that keeps the Bialaddin control know on the shaft but these are way too small! Nevermind, I'm sure I'll find a use for them one day!

    BTW, the OD is 1.7mm!
     
  2. JonD

    JonD Subscriber

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    They're huge @ColinG.
    A recent project here used 13BA.
    Drill 0.8mm then Tap M1

    sw_rotors2.jpg
     
    Last edited: Jun 6, 2021
  3. ColinG

    ColinG United Kingdom Subscriber

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    13BA! That's incredible!
     
  4. JonD

    JonD Subscriber

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    They came from here.

    BA Fasteners, Imperial Fasteners, Micro Metric Stainless, Small Screws, UNC Square Nuts, Ba Screws, Ba Bolts,

    That is a switch rotor from a piece of radio test equipment. The fingers are mounted by plastic pips which go brittle and the contacts fall off and get lost.
    I machined that pair of contacts and refitted them using the screws. Hope not to have to go in there again since assembling the unit is very awkward.

    Sorry about off topic - but hopefully someone might find the screw link useful.
     
  5. steerpike451

    steerpike451 United Kingdom Subscriber

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    Believe it or not, the original BA specification goes down to 25 BA (od 0.25mm), although I don't think anyone went much below 16 BA. FYI the retaining screw in the Bialaddin knob is 6 BA- positively chunky!
     
  6. MYN

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    Possibly, if you're going to fix something like a mechanical wrist watch.
     

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