Old and unusual screw sizes

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  • joecb

    US Member - 2 Years
    Replies: 498
    Topics: 63
    #247056

    Hello all. Following up on a discussion about old/ obsolete American Standard Screw sizes… I found my reference chart for sizes from #2 to #30 . This from an old fastener manufacturing company. When measuring the diameter of the thread, remember that the thread will be a few thousands smaller that the nominal body size.

    Hope it will be useful and prevent problems from “almost alike” fasteners.

    Joe B

    American_Screw_Co_standard

    • This topic was modified 1 month ago by joecb.
    • This topic was modified 1 month ago by Mumbles.
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    Mumbles

    Canada Member - 2 Years
    Replies: 5174
    Topics: 276
    #247060

    That’s a handy chart and thanks for posting it!

    And there are the #14 screws Johnson used on their rope sheaves which commonly get mistaken for being 1/4″.

    What is the length the last column would be referring to?


    joecb

    US Member - 2 Years
    Replies: 498
    Topics: 63
    #247061

    The lengths in the last column, are the standard range of lengths that this company , The American Screw Company produced.

    Joe B

    1 user thanked author for this post.

    The Boat House


    Replies: 3565
    Topics: 88
    #247095



    Early Johnson had an odd shear pin Dia. as
    well. I haven’t had any luck finding brass rod
    that size.
    Tubs

    You're only as smart as the person you're talking to.


    pm-t2

    Canada Member - 2 Years
    Replies: 476
    Topics: 30
    #247164

    The screws used in the earlier Johnson rope sheaves are 10-30 screws. My South Bend lathe has no setting for cutting 30 threads per inch. My Cardiff does, but I don’t have the necessary headstock gear for it. I bought a 10-30 die from a place in Michigan for 11 dollars US. I use it to make new rope plate screws, and also made screws that work with my puller kit so I don’t have to hammer on the flywheel nut to get the flywheel off.

    But here’s one for you. Check out the slotted hex-head bolts that are used to fasten the cylinder castings to the crankcase. They are 20 TPI but the major diameter measures at about 0.260″, whereas most 1/4″ fasteners measure a few thou under 0.250″. Using a regular 1/4-20 fastener is not recommended for that particular application.

    Hope it helps, but it’s somebody else’s fault if it doesn’t

    Best,
    PM T2


    joecb

    US Member - 2 Years
    Replies: 498
    Topics: 63
    #247236

    Dear Prime Minister … 0.260 (that be 6.604 mm for some of you guys) is likely the #16 -20 from the chart, body diameter of 0.268

    Joe B


    The Boat House


    Replies: 3565
    Topics: 88
    #247245



    This is the little bugger. Luckily they don’t
    get the attention that the flywheel screws do
    so they are, normally, still in good condition.
    Tubs

    You're only as smart as the person you're talking to.


    Buccaneer

    US Member - 1 Year
    Replies: 5086
    Topics: 831
    #247486

    I ran across an odd size thread today, on the 1925 Elto Lightwin, model C,
    on the water outlet tube that goes thru the exhaust manifold.
    I had no tap or die for this one.

    The thread OD measured .388, and it has 27 TPI.
    I didn’t even know my thread gauge has 27 tpi, let
    alone hear of that thread.

    DSCN1817

    Prepare to be boarded!

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    joecb

    US Member - 2 Years
    Replies: 498
    Topics: 63
    #247497

    One encounters 27 tpi on some pipe fittings, with out going down to the shop to measure, I’ll bet that that is a 1/8 NPS ( National Pipe Straight) as opposed to the common 1/8 NPT ( Tapered) , both are 27 TPI. I think that if you go to a lamp supply store , you will discover that the common threaded tube in most light fixtures is 1/8 (27 tpi) NPS

    AND yet another caution… careful that there is a British 1/8 pipe that is 28 TPI

    All this is great fun , and we haven’t even gotten into the metric and Whitworth stuff yet.

    Joe B


    Buccaneer

    US Member - 1 Year
    Replies: 5086
    Topics: 831
    #247500

    Joe, I should have thought about the pipe thread possibility!
    The specs I found are pretty close to what I have…….

    Nominal Pipe Size (inch) – 1/8″ NPT
    No. Of Threads Per Inch – 27
    Outside Dia. (inch) – 0.405

    Prepare to be boarded!


    amuller

    US Member - 1 Year
    Replies: 1021
    Topics: 157
    #247501

    Thank you! I’ve never had a numbered machine screw chart that went as high as 30. My copy of Machinery’s Handbook (1976) does not go above #12.

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