1954 Hardinge HLV apron clutch hex "grub" screw thread
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    Default 1954 Hardinge HLV apron clutch hex "grub" screw thread

    Hopefully this is one of those emails someone will know the answer to.

    Note: British machine!

    Measured major diameter 0.148" to 0.152" or 3.75mm length; 0.225" or 5.73mm. I have spent an hour with a magnifying glass and strong light and appears to be 36 tpi or 0.7mm pitch.

    What's the thread?

    Russ

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    I would try an M4 screw in the hole and an M4 nut on your grub screw. There is such a thing as ASME 7-36, but it was very obsolete long before the lathe was designed. In the original Hardinge Cataract machines made from 1903 to 1930 in Chicago, an 8-36 screw would be a possibility, but probably not in England (or Elmira) in 1954. All of my Elmira-built machines have UNC and UNF fasteners. The Chicago machines have lots of obsolete threads.

    What threads are used on the stock-type screws in your lathe? Are they metric, BA, BSF, Whitworth, UNC or UNF? I suppose the special screws made by Hardinge might use a different thread standard from the purchased standard fasteners.

    Larry

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    7-36 ASME, American Society of Mechanical Engineers.

    According to my 10 th edition of Machinery's Handbook, thrid printing dated 1941 the ASME threads have been superseded by the American Standard series ANC & ANF aka UNC & UNF loosing the no 7 size. Guess Hardinge were behind the times.

    I have a comprehensive list of threads in major diameter order and there is nothing sufficiently close to either almost fit or safely modify. M4 is nearest at 0.1570 major diameter, 0.1240 core and 36.3 TPI. Won't hold well if re-tapped. 7-36 ASME core is 0.1149 core.

    3BA might work but thats almost as obscure.

    M4.5 most likely to be safe to re-tap at 0.1770 major, 0.1410 core and 33.9 TPI but that is mildly obscure too. Listed as a preferred size but getting it is a different matter.

    Clive

    Larry types faster.

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    The british HLVs used UNF threads the same as the US ones.

    Both of the grub screws in question on my machine are BA threads, but that's because the original disks had split and I made new ones (along with the shafts, gears etc, etc!)

    It could easily be a 7-36 since the location is fairly cramped and the steel is hardened.

    Might be easiest to make and harden a new disk and tap for a grub screw that you can get.. The hole in the centre isn't anything special. 1/4" UNF or similar.


    PS. Clive got there first

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    Thanks guys for the answers so far!

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    Quote Originally Posted by L Vanice View Post
    I would try an M4 screw in the hole and an M4 nut on your grub screw. There is such a thing as ASME 7-36, but it was very obsolete long before the lathe was designed. In the original Hardinge Cataract machines made from 1903 to 1930 in Chicago, an 8-36 screw would be a possibility, but probably not in England (or Elmira) in 1954. All of my Elmira-built machines have UNC and UNF fasteners. The Chicago machines have lots of obsolete threads.

    What threads are used on the stock-type screws in your lathe? Are they metric, BA, BSF, Whitworth, UNC or UNF? I suppose the special screws made by Hardinge might use a different thread standard from the purchased standard fasteners.

    Larry
    8-36 and M4 are close enough for practical purposes to interchange, just about.


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