# Why does an auto parts store stock 3/16-32 screws? **URL:** \ **Category:** Factual Questions\ **Created:** [May 31, 2011, 9:48pm UTC](https://boards.straightdope.com/t/why-does-an-auto-parts-store-stock-3-16-32-screws/583902 "2011-05-31T21:48:51Z")\ **Posts on this page:** 15\ **Page:** 1
**Author:** ![thelabdude](https://avatars.discourse-cdn.com/v4/letter/t/dc4da7/32.png) [@thelabdude](https://boards.straightdope.com/u/thelabdude)\ **Post date:** [May 31, 2011, 9:48pm UTC](https://boards.straightdope.com/t/why-does-an-auto-parts-store-stock-3-16-32-screws/583902/1 "2011-05-31T21:48:51Z")
I say they have never been common in the automotive industry. The American companies now are largely using metric the same as much of the world has for a long time. Before they went metric, below 1/4’’ they used number fasterers, #10, #8, etc. Maybe the 3/16’’ specification was always around, but why start using something in place of a more common fastener? I think it was over 10 years ago I first ran into a 3/15’’ screw. I needed to replace a #10 screw in my chain saw. Now there really isn’t that much difference, 0.190’’ vs. 0.1875’’, but when going into a tapped hole in an aluminum housing, you don’t want a sloppy fit. Who done it? I smell the work of the ISO. For an engineer designing new products or a manufacturer building them no big deal. So we make it harder to repair our existing stock in order to make it easier for foreign countries to sell in our market? ---
**Author:** ![lisiate](https://avatars.discourse-cdn.com/v4/letter/l/f05b48/32.png) [@lisiate](https://boards.straightdope.com/u/lisiate)\ **Post date:** [May 31, 2011, 10:28pm UTC](https://boards.straightdope.com/t/why-does-an-auto-parts-store-stock-3-16-32-screws/583902/2 "2011-05-31T22:28:06Z")
Are you asking about 3/16" or 3/15"? 3/15" is almost exactly 5mm. So that would probably be a metric thing. ---
**Author:** ![RedSwinglineOne](https://avatars.discourse-cdn.com/v4/letter/r/a9adbd/32.png) [@RedSwinglineOne](https://boards.straightdope.com/u/RedSwinglineOne)\ **Post date:** [May 31, 2011, 10:31pm UTC](https://boards.straightdope.com/t/why-does-an-auto-parts-store-stock-3-16-32-screws/583902/3 "2011-05-31T22:31:15Z")
I don’t know how common 3/16-32 screws were, but they were more common than they are now. They are now considered obsolete. I doubt anybody has “just started” using them for anything. Auto parts stores sell them for the same reason they sell anything. They are/were used on cars and they occasionally wear out and need to be replaced. ---
**Author:** ![thelabdude](https://avatars.discourse-cdn.com/v4/letter/t/dc4da7/32.png) [@thelabdude](https://boards.straightdope.com/u/thelabdude)\ **Post date:** [June 1, 2011, 1:45am UTC](https://boards.straightdope.com/t/why-does-an-auto-parts-store-stock-3-16-32-screws/583902/4 "2011-06-01T01:45:17Z")
No, I never saw a 3/16’’ screw until at least the 90’s. As I said in my OP, American cars used #10 screws until they went metric. None of the cars needing screws ever used 3/16’’. As for metric, Yes the 5 mm screws are nearly the same, but their 0.8 thread pitch is much coarser than a 10-32. The #10 was the standard for most of the 20’th century and now all you can find is the 3/16’’. ---
**Author:** ![rat\_avatar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rat_avatar/32/255_2.png) [@rat\_avatar](https://boards.straightdope.com/u/rat_avatar)\ **Post date:** [June 1, 2011, 2:08am UTC](https://boards.straightdope.com/t/why-does-an-auto-parts-store-stock-3-16-32-screws/583902/5 "2011-06-01T02:08:01Z")
Are you sure they aren’t selling #10 as 3/16 to reduce the need to explain number sizes to their typical customers? I think that is most likely as what you are speaking of as a 10-32 is a ASME/ANSI UNF and I doubt the ISO would bother with non-metric screw sizes. ---
**Author:** ![thelabdude](https://avatars.discourse-cdn.com/v4/letter/t/dc4da7/32.png) [@thelabdude](https://boards.straightdope.com/u/thelabdude)\ **Post date:** [June 1, 2011, 3:36am UTC](https://boards.straightdope.com/t/why-does-an-auto-parts-store-stock-3-16-32-screws/583902/6 "2011-06-01T03:36:23Z")
I guess that is possible. I haven’t checked any with a micrometer. it certainly never hurts to avoid expecting people to know what they are doing. ---
**Author:** ![BlackNGold](https://avatars.discourse-cdn.com/v4/letter/b/779978/32.png) [@BlackNGold](https://boards.straightdope.com/u/BlackNGold)\ **Post date:** [June 1, 2011, 10:58am UTC](https://boards.straightdope.com/t/why-does-an-auto-parts-store-stock-3-16-32-screws/583902/7 "2011-06-01T10:58:38Z")
A 3/16 screw \*is[/] a #10, just an odd nomenclature. Just like some screws are labeled #14 instead of 1/4. ---
**Author:** ![thelabdude](https://avatars.discourse-cdn.com/v4/letter/t/dc4da7/32.png) [@thelabdude](https://boards.straightdope.com/u/thelabdude)\ **Post date:** [June 1, 2011, 12:52pm UTC](https://boards.straightdope.com/t/why-does-an-auto-parts-store-stock-3-16-32-screws/583902/8 "2011-06-01T12:52:06Z")
> [@BlackNGold](#): > > A 3/16 screw \*is[/] a #10, just an odd nomenclature. Just like some screws are labeled #14 instead of 1/4. No, they are different, close but different. Although in this sloppy era, I can see mislabeling. So you buy a 1/4’’ and it really is a #14 and doesn’t fit right. That is another problem, #12 and #14 wood screws coming crawling out of the wood work after years and years of obsolescence. ---
**Author:** ![Hbns](https://avatars.discourse-cdn.com/v4/letter/h/8edcca/32.png) [@Hbns](https://boards.straightdope.com/u/Hbns)\ **Post date:** [June 1, 2011, 3:01pm UTC](https://boards.straightdope.com/t/why-does-an-auto-parts-store-stock-3-16-32-screws/583902/9 "2011-06-01T15:01:08Z")
Found mounting directions ([PDF](http://www.arcticsnowplows.com/english/manuals/52128.pdf)) for Arctic brand snow plows that call for 3/16-32 screws. Also have run across them on some old Brit stuff. This [chart](http://www.astronomiainumbria.org/advanced_internet_files/meccanica/easyweb.easynet.co.uk/_chrish/threadz.htm) seems to support the notion it is a British norm. ---
**Author:** ![Hbns](https://avatars.discourse-cdn.com/v4/letter/h/8edcca/32.png) [@Hbns](https://boards.straightdope.com/u/Hbns)\ **Post date:** [June 1, 2011, 3:12pm UTC](https://boards.straightdope.com/t/why-does-an-auto-parts-store-stock-3-16-32-screws/583902/10 "2011-06-01T15:12:11Z")
Missed the edit window. Definitely a British standard. [British Standard Fine (BSF)](http://www.britishfasteners.com/threads/bsf.html) ---
**Author:** ![RedSwinglineOne](https://avatars.discourse-cdn.com/v4/letter/r/a9adbd/32.png) [@RedSwinglineOne](https://boards.straightdope.com/u/RedSwinglineOne)\ **Post date:** [June 1, 2011, 3:28pm UTC](https://boards.straightdope.com/t/why-does-an-auto-parts-store-stock-3-16-32-screws/583902/11 "2011-06-01T15:28:25Z")
> [@thelabdude](#): > > The #10 was the standard for most of the 20’th century and now all you can find is the 3/16’'. Sorry **thelabdude** , I sell screws for a living and absolutely nobody is pushing the use of 3/16-32 screws, and they have not replaced 10-32. In 15 years I have gotten maybe 3 calls on 3/16-32 screws and they were all to replace screws on old cars or antique sewing machines. They are currently not used in fabrication at all. If you can’t find 10-32 screws you’re not really looking. ---
**Author:** ![KP](https://avatars.discourse-cdn.com/v4/letter/k/a9adbd/32.png) [@KP](https://boards.straightdope.com/u/KP)\ **Post date:** [June 1, 2011, 3:31pm UTC](https://boards.straightdope.com/t/why-does-an-auto-parts-store-stock-3-16-32-screws/583902/12 "2011-06-01T15:31:27Z")
It’s bad enough when nail heads start to protrude. Now screws are crawling out of woodwork? ---
**Author:** ![thelabdude](https://avatars.discourse-cdn.com/v4/letter/t/dc4da7/32.png) [@thelabdude](https://boards.straightdope.com/u/thelabdude)\ **Post date:** [June 1, 2011, 8:23pm UTC](https://boards.straightdope.com/t/why-does-an-auto-parts-store-stock-3-16-32-screws/583902/13 "2011-06-01T20:23:13Z")
> [@RedSwinglineOne](#): > > Sorry **thelabdude** , I sell screws for a living and absolutely nobody is pushing the use of 3/16-32 screws, and they have not replaced 10-32. In 15 years I have gotten maybe 3 calls on 3/16-32 screws and they were all to replace screws on old cars or antique sewing machines. They are currently not used in fabrication at all. > If you can’t find 10-32 screws you’re not really looking. Been in a hardware store lately? ---
**Author:** ![RedSwinglineOne](https://avatars.discourse-cdn.com/v4/letter/r/a9adbd/32.png) [@RedSwinglineOne](https://boards.straightdope.com/u/RedSwinglineOne)\ **Post date:** [June 2, 2011, 8:39pm UTC](https://boards.straightdope.com/t/why-does-an-auto-parts-store-stock-3-16-32-screws/583902/14 "2011-06-02T20:39:19Z")
> [@thelabdude](#): > > Been in a hardware store lately? Yes, I go to hardware stores quite often. ---
**Author:** ![Gbro](https://avatars.discourse-cdn.com/v4/letter/g/c6cbf5/32.png) [@Gbro](https://boards.straightdope.com/u/Gbro)\ **Post date:** [June 2, 2011, 10:48pm UTC](https://boards.straightdope.com/t/why-does-an-auto-parts-store-stock-3-16-32-screws/583902/15 "2011-06-02T22:48:15Z")
You see them because nobody buys them. Buy them out at that store and I will bet you 6 bits they will never replace them. I work part time at a parts store and we are also a limited hardware (auto specific for the most part) store. That also would include someone wanting 2 dozen 3-16" x 2" screw that I will call a “Stove Bolt” and when I source it I find them 100ea and then 75ea sit on the shelf forever.