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Thread: JIS Threads

  1. #11

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    The pipe and hydraulic threads on most Japanese excavators are still BSP (British Standard Pipe) to this day. Many of the Eastern countries still use Whitworth threads on devices.

    My '69 Morgan had a combination of Whitworth, BSF, BSP, UNC, UNF, and metric threads and fasteners! Also an NPT fitting for the oil pressure line from the engine.

  2. #12
    Join Date
    Aug 2004
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    York, PA
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    If we are talking about metric thread close to M3, but not the standard M3 x 0.5, it could be M3 x 0.6. Yes, it is non-standard, but taps and dies are available with this thread from Ebay.

    If I were you, I would try to measure the thread the best I can. If you don't have any original screws, you can try forcing a wooden dowel into the threaded hole and measure the pitch from thread impression on the wood. You can also make a few trial screws with different pitches on your lathe and see which one fits the best. My 12 x 36 Grizzly lathe allows me to cut a lot of non-standard pitches. This information is not available from the lathe manual, but one smart guy developed a full table for my lathe, listing all possible pitches and corresponding change gears and gearbox settings.

  3. #13
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    Quote Originally Posted by Leadfootin View Post
    The pipe and hydraulic threads on most Japanese excavators are still BSP (British Standard Pipe) to this day. Many of the Eastern countries still use Whitworth threads on devices.

    My '69 Morgan had a combination of Whitworth, BSF, BSP, UNC, UNF, and metric threads and fasteners! Also an NPT fitting for the oil pressure line from the engine.
    Pipe and hydraulic threads on MOST of anything are still BSP(T) as it is most commonly used international ISO/EN/DIN standard anywhere else exept US.
    Yes, even all the "metric" countries use it even if its not really metric... probably some political horsing around compromise to get brits using meTRes. Or ages old traditions

    Even DIN 2353 metric tube/pipe hydraulic fittings use Whitworth thread. Hydraulic tube OD sizes are nice millimeter numbers like 6mm, 8mm, 10mm etc but the thread on other end is BSP(T)
    I should probably call these tube fittings as the they are is sold based on outside diameter..

  4. #14
    Join Date
    Aug 2005
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    103

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    I pulled the remaining switches and managed to find one without mangled threads and a good screw. Looks to be a .6 pitch as Mikey553 suggested. Will give that a try (M3 x .6) and if the thread form is different, will see if there is a BA Std equivalent. Many thanks for the responses. And glad I don't have a Morgan after reading that hodgepodge of fastener stew...

  5. #15
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    Quote Originally Posted by derekg View Post
    I pulled the remaining switches and managed to find one without mangled threads and a good screw. Looks to be a .6 pitch as Mikey553 suggested. Will give that a try (M3 x .6) and if the thread form is different, will see if there is a BA Std equivalent. Many thanks for the responses. And glad I don't have a Morgan after reading that hodgepodge of fastener stew...
    I think it would be rather difficult to determine the threadform on these small sizes. 55 or 60 degrees are both probably enough close for your use if they just fit.
    BA-5 is 0.59mm pitch and 3.2mm nominal OD. Pretty damn close to the M3x0.6 or M3.5x0.6 (M3.5 is semi-common on electrical equipment)
    0.59mm vs 0.60mm pitch is really hard to distinguish if engagement is only couple of turns. Over 10 turns and it starts to show up (0.1mm error) and anything over 20 turns is pretty much guaranteed to bind.

  6. #16
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    Aug 2005
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    Excellent. I will try to get a set of those. There are only about 5 turns to the screw, but I'd still like to get the correct fit. Thanks, Derek

  7. #17
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    May 2002
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    Derek,
    What is the diameter of the good screw you have? There is a difference in diameter between M3 and 5 BA which should be apparent.

  8. #18
    Join Date
    Aug 2005
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    103

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    "Yes, Virginia, there is a Santa Claus..."

    So the wife unit asked me to head up into the attic to pull down the Christmas ornaments and such. While crawling around the attic I saw something very Datsun-like. Sure enough, 4 large storage bins full of vintage rare uncut Datsun wiring harnesses from the 1960's replete with switches, knobs, and these crazy little screws. Best I can figure it is about 15+ years ago I went on a buying spree for all the vintage harnesses and switches I could find since I knew they would become impossible to find. I then stashed them and totally forgot they were there. Sure, you can say, "how could your forget such things?", but it's pretty easy as you run through a ton of vintage cars and motorcycles. It all becomes a blur I'm still going to search for the replacements and greatly appreciate the help you all have provided, but am happy that I just managed to install everything with my new (old) found loot. Merry Christmas to me...

  9. #19
    Join Date
    Jan 2004
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    Missouri
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    29,672

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    Hah...

    The answer to "why do you keep all this old junk?"
    1601

    Keep eye on ball.
    Hashim Khan

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