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Thread: JIS Threads

  1. #1
    Join Date
    Aug 2005
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    103

    Default JIS Threads

    Howdy folks,

    Been a while. I'm doing more stupid automative things, this time with a 1966 Datsun 411. Italian body design, MGB engine copy, using mostly SAE sizes. An oddball for sure. The issue I have now is finding some teeny, tiny screws that hold the old knobs onto the shafts of old switches. The thread does not fit my SAE or Metric gauges with an M3 being the closest diameter, but none of the pitches will work. They all bind. So, I am thinking, because these switches were used on other less oddball cards (like the Datsun Roadster), that the thread just might be JIS. The problem is that I cannot find a JIS blade style gauge and really don't want to shell out for the ring gauges just to be proven wrong. The thread is different than a standard 60 degree vee (more like a Whitworth - yes, another fun thread):

    http://www.ring-plug-thread-gages.co...rticle-JIS.pdf

    As such, not sure how I would even cut it on a lathe, besides being too small and fine for my ham-fisted work.

    My question is whether any of you have seen thread gauges for JIS as I cannot find them online. McMaster-Carr has M3 JIS screws, but given their gold plated shipping charges I'd like to be sure first.

    Many thanks, Derek

  2. #2
    Join Date
    Dec 2016
    Location
    Helsinki, Finland, Europe
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    2,649

    Default

    Quote Originally Posted by derekg View Post
    Howdy folks,

    Been a while. I'm doing more stupid automative things, this time with a 1966 Datsun 411. Italian body design, MGB engine copy, using mostly SAE sizes. An oddball for sure. The issue I have now is finding some teeny, tiny screws that hold the old knobs onto the shafts of old switches. The thread does not fit my SAE or Metric gauges with an M3 being the closest diameter, but none of the pitches will work. They all bind. So, I am thinking, because these switches were used on other less oddball cards (like the Datsun Roadster), that the thread just might be JIS. The problem is that I cannot find a JIS blade style gauge and really don't want to shell out for the ring gauges just to be proven wrong. The thread is different than a standard 60 degree vee (more like a Whitworth - yes, another fun thread):

    http://www.ring-plug-thread-gages.co...rticle-JIS.pdf

    As such, not sure how I would even cut it on a lathe, besides being too small and fine for my ham-fisted work.

    My question is whether any of you have seen thread gauges for JIS as I cannot find them online. McMaster-Carr has M3 JIS screws, but given their gold plated shipping charges I'd like to be sure first.

    Many thanks, Derek
    To me the JIS standard looks like just a copy-paste of metric(including withworth pipe) and american unified.

    Maybe yours is BSF.
    Or if thread pitch doesnt make any sense in metric or per inch try BA:
    https://en.wikipedia.org/wiki/Britis..._screw_threads

  3. #3
    Join Date
    Sep 2012
    Location
    Australia
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    379

    Default

    JIS is Metric. I would bust out the calipers, and do a very close comparison to the BA standard threads, a BA5 or BA6 probably. BA was used in electrical components not infrequently back in the day, especially those made for Commonwealth markets.

  4. #4
    Join Date
    Jan 2004
    Location
    Missouri
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    Default

    Seems like JIS may be one of the "alternate standard metric" versions, where some of the size/pitch combinations do not agree with anyone else. But with screws such as you mention, it may be an oddball that you will have a hard time finding.

    The smaller sizes are standard. its the 8mm and above where the trouble starts.

    https://www.boltdepot.com/fastener-i...ead-pitch.aspx
    Last edited by J Tiers; 12-05-2018 at 10:34 PM.
    1601

    Keep eye on ball.
    Hashim Khan

  5. #5
    Join Date
    Apr 2017
    Location
    Kelowna BC
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    1,590

    Default

    My lathe does not care what pitch of thread form as long as it's in the gearbox.
    What pitch is it ?

  6. #6
    Join Date
    Jan 2003
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    Deep in the Heart of Texas!
    Posts
    7,617

    Default

    If it were me, I'd be tapping the threads to something I CAN get my hands on. Even if it was a point car, I guarantee no judge will be checking the knob screw threads.

  7. #7
    Join Date
    Aug 2004
    Location
    Sunny So Cal
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    4,494

    Default

    Quote Originally Posted by derekg View Post
    Howdy folks,

    Been a while. I'm doing more stupid automative things, this time with a 1966 Datsun 411. Italian body design, MGB engine copy, using mostly SAE sizes. An oddball for sure.

    Many thanks, Derek
    What caught my eye was the Italian body. I had a fiat, 69 and it spec'ed out some threads in the shop manual. The JIS is what caught my eye. What is that spec? Japanese market or a variant of threads.

    I did what this guy said. JR


    CCWKen

    If it were me, I'd be tapping the threads to something I CAN get my hands on
    My old yahoo group. Bridgeport Mill Group

    https://groups.yahoo.com/neo/groups/...port_mill/info

  8. #8
    Join Date
    May 2002
    Location
    Auckland, New Zealand
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    1,408

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    Derek,
    Have you got any of the screws or do you only have the female thread? If the former, tell us the screw diameter and its TPI or pitch using either an inch or metric screw pitch gauge and someone here will find it.

    Apologies if this is stating the obvious, (you have confused me with mention of ring gauges), I am wondering if you have the ordinary inch and metric screw pitch gauges that fold out like a set of feeler gauges.

  9. #9
    Join Date
    Oct 2002
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    Saskatoon, Saskatchewan
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    2,832

    Default

    Well, if you want to spend your time looking to see what thread it might be, you might find it here.

    https://www.gewinde-normen.de/en/index.html

  10. #10
    Join Date
    Dec 2016
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    Helsinki, Finland, Europe
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    Default

    Quote Originally Posted by J Tiers View Post
    Seems like JIS may be one of the "alternate standard metric" versions, where some of the size/pitch combinations do not agree with anyone else. But with screws such as you mention, it may be an oddball that you will have a hard time finding.

    The smaller sizes are standard. its the 8mm and above where the trouble starts.

    https://www.boltdepot.com/fastener-i...ead-pitch.aspx
    Interesting. In larger sizes "they" use fine pitch metric thread as "standard" size.
    (JIS "equivalent" M20x1.5 is also listed on ISO/DIN standards and available at local tractor supply here)

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