Old and unusual screw sizes

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  • joecb

    US Member - 2 Years
    Replies: 609
    Topics: 73
    #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 10 months, 3 weeks ago by joecb.
    • This topic was modified 10 months, 3 weeks ago by Mumbles.

    Mumbles

    Canada Member - 2 Years
    Replies: 5514
    Topics: 293
    #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: 609
    Topics: 73
    #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: 3905
    Topics: 99
    #247095



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


    pm-t2

    Canada Member - 2 Years
    Replies: 500
    Topics: 35
    #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: 609
    Topics: 73
    #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: 3905
    Topics: 99
    #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


    Buccaneer

    US Member - 1 Year
    Replies: 5905
    Topics: 906
    #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!


    joecb

    US Member - 2 Years
    Replies: 609
    Topics: 73
    #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: 5905
    Topics: 906
    #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: 1041
    Topics: 161
    #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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