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Screw Threads

This topic contains 15 replies, has 9 voices, and was last updated by  TopNotch 1 week, 3 days ago.

Viewing 16 posts - 1 through 16 (of 16 total)
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  • #647843

    TopNotch
    Pro
    elmwood park, NJ

    Not sure where to post this but I’ve encountered the problem with electrical so here I go.
    I have taken your typical number 8 thread of a screw and have gone to the store checked it and when I got back it was too tight for the fitting.
    So the question is if it’s not metric and it’s not standard is there a different machine size thread bigger than a six smaller than an eight. I’m wondering if brass stove bolts or machine screws are threaded differently.

    Anyone know not sure if I’m explaining this right?

    Working Pro since 1993

    Tom M

    #647847

    A screw (with a pointy end for wood or metal), or a machine screw (with a flat end, meant to go into a nut or threaded hole)?

    My You Tube channel: https://www.youtube.com/channel/UCA5AretE3xPoVDV61AxUdUA

    I don't do a fast job. I don't do a slow job. I do a half fast job.

    #647853

    TopNotch
    Pro
    elmwood park, NJ

    A machine thread flat possibly tapered. That threads into an electrical fixture or other kind of decorative object.

    A number 7 would be ideal but I have never seen any.

    Working Pro since 1993

    Tom M

    #647858

    RyanF
    Pro

    So you’re saying the 6 is too loose? That’s the typical size. Ive never heard of a 7. Is this a junction box youre trying to screw into?

    #647860

    Sprokitz
    Pro
    Easton, Pa

    Metric M4-0.5 That’s 36 TPI and is somewhere around .007 smaller in diameter than 8-36.
    Metric M4-0.7 is 32 TPI and .007 smaller than 8-32
    But I would double check that

    #647862

    TopNotch
    Pro
    elmwood park, NJ

    Metric M4-0.5 That’s 32 TPI and is somewhere around .007 smaller in diameter than 8-32. But I would double check that

    I grabbed a few of those just in the thread checker I used was worn. I will see tomorrow.

    Last time this happened I was putting up some half assed pendant and the attachment brackets wouldn’t work with the type of box my electrician used. I threaded longer screws in then after I trimmed the excess the screw Caps wouldn’t work.

    Working Pro since 1993

    Tom M

    #647871

    jponto07
    Moderator
    Bloomington, IN

    Not sure where to post this but I’ve encountered the problem with electrical so here I go.
    I have taken your typical number 8 thread of a screw and have gone to the store checked it and when I got back it was too tight for the fitting.
    So the question is if it’s not metric and it’s not standard is there a different machine size thread bigger than a six smaller than an eight. I’m wondering if brass stove bolts or machine screws are threaded differently.

    Anyone know not sure if I’m explaining this right?

    Is the issue fine thread vs coarse thread maybe?

    Jon P.
    Timber Carpentry & Construction
    https://www.facebook.com/timbercarpentry/
    Instagram

    #647885

    Metric M4-0.5 That’s 32 TPI and is somewhere around .007 smaller in diameter than 8-32. But I would double check that

    I grabbed a few of those just in the thread checker I used was worn. I will see tomorrow.

    Last time this happened I was putting up some half assed pendant and the attachment brackets wouldn’t work with the type of box my electrician used. I threaded longer screws in then after I trimmed the excess the screw Caps wouldn’t work.

    Yeah, sometimes electrical stuff seems to have sizes of it’s own. I may be wrong in my memory, but I think standard fine thread machine screws are 28 threads per inch and, as mentioned, electrical will be 32. That is in imperial sizes. We have metric now too, as also mentioned, but I would think that they are in a metric thread size too as every other metric fastener has metric threads that I can think of. Although, it may be one of those sizes that are really really close, so that could mess you up too. I never throw any of those things out. There’s always a project comes up like you have now when it’s nice to be able to go out to the box of crap looking for the right fastener.

    My You Tube channel: https://www.youtube.com/channel/UCA5AretE3xPoVDV61AxUdUA

    I don't do a fast job. I don't do a slow job. I do a half fast job.

    #647912

    Ceiling boxes use an 8-32 screw (10-24 for ceiling fan boxes). Switch/receptacle boxes use a 6-32. If you are referring to the screw that comes with the light fixture, they are often metric. It would help if you could specify exactly where the screw goes.

    Anything is possible if your wallet is thick enough ~ my father

    #647922

    Sprokitz
    Pro
    Easton, Pa

    I may be wrong in my memory,

    Yup, me too LOL

    #647953

    theamcguy
    Pro
    Fayetteville, NC

    #8 screws have 2 common thread pitches 8-32 and 8-36. They look the same to the eye but what you describe as jamming in the hole means you are using the wrong thread pitch.

    Automotive Pro
    Fayetteville, NC

    #647995

    RonW
    Pro
    Holladay, Tn

    Ceiling boxes use an 8-32 screw (10-24 for ceiling fan boxes). Switch/receptacle boxes use a 6-32. If you are referring to the screw that comes with the light fixture, they are often metric. It would help if you could specify exactly where the screw goes.

    That’s good to know!
    Nice to see you stopping by Garrett.

    Ron

    A Working Pro since 1994!

    Member since March 26, 2014.

    #648027

    Boschmanbrian
    Pro
    Montreal , QC, Canada

    Take a look at this chart,
    It’s for tapping, but it is taps for many different screws.

    #648154

    TopNotch
    Pro
    elmwood park, NJ

    Ceiling boxes use an 8-32 screw (10-24 for ceiling fan boxes). Switch/receptacle boxes use a 6-32. If you are referring to the screw that comes with the light fixture, they are often metric. It would help if you could specify exactly where the screw goes.

    I have a couple of different electrical strippers both with thread cutters and neither have metric thread options. If they make them I will have to invest.
    I think more and more people buying stuff off the internet are coming back with metric fasteners over standard.

    @theamcguy I have never heard of a 8/36 thread

    Working Pro since 1993

    Tom M

    #648227

    theamcguy
    Pro
    Fayetteville, NC

    @theamcguy I have never heard of a 8/36 thread

    8-32 is the coarse thread and 8-36 is the fine thread. They are really close and easy to mix up.

    Automotive Pro
    Fayetteville, NC

    #648257

    TopNotch
    Pro
    elmwood park, NJ

    Is 8/36 typically found in automotive.

    Working Pro since 1993

    Tom M

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