#10 screw and 3/16 screw

[rotate]

I'm feeling like an idiot. I have box of set screws marked 3/16-24. I was looking at my tap & die set and noticed that I don't have a 3/16-24 tap, but #10-24 looked almost identical so I used that. It worked although the set screw felt a little loose.

So, what's the deal with #10-24 and 3/16-24? I feel like such a space cadet.

[Don Young]

I don't know the exact specifications, but for common hardware they are basically the same. I think that 3/16-24 is pretty much obsolete, replaced by 10-24. The preference seems to be to use inch dimensions for 1/4" and above with machine screw numbers for smaller sizes.

[Rich Carlstedt]

The switch from Inch to Number measuring for "small" threads produced some
wierdcases. These are generally threads less than 1/4"
In Number Screw sizes, You start with .060 as a base and it is a 0-80 thread, or 0-72 etc.
( Please note that .0625 is 1/16 , so " )" is close to that fraction benchmark)
Each sequential thread size grows by .013" and gains one digit.
A 1-72 for example is .073" and a 2-56 is .086 in the "Major Diameter" measurement.
A 10-32 is .060 PLUS .130 ( 10 x .013) or .190
Your old 3/16 thread is .1875"
The only "exact" one is 1/8-40 (ie.) as it meets a 5-40 (.060+.065) at .125 dead on.

Real confusion is with the #14 threads (.060 + .182) as its .242
So if you have a 1/4 -20 bolt, it will not fit a 14-20 hole !

Old machines and hardware still use the old standard of 100 ago

Its a lot easier, to refer to numbers than fractions.
Can you imagine doing a 5/64-72 or a similar ?
It was an attemp to make the range smaller than 1/64's
Of course it doesn't get a simpler than Metric..but I won't go there

Rich

[Machinist-Guide]

Here is a link to a tap drill chart for number screws if you need one

Number Screw Tap Drill Chart

[mardtrp]

Oh the joys of playing with that outdated MONGREL system , it's about time you lot converted to the easiest system of them all, metric.


Mark

[J Tiers]

Oh the joys of playing with that outdated MONGREL system , it's about time you lot converted to the easiest system of them all, metric.


Mark

yep, the system with 5 different possible pitches for an M12 (or is it M14) screw........

And the "standard" pitches differing depending on which country the screw is from.....

And the 4 selectable gears on the thread dial...... with the little book to tell you which to use, unless its one of the oddballs

Yah, metric isn't standardized, it's just standard....... And just as standardly effed up as "imperial".

Besides, teh 3/16 size is ancient, non-standard, and incompatible with modern ones....... It dates from before the time 130 years ago when the US officially converted to Metric.

I DO have taps and dies for 3/16, and for #12, and some other oddities

And for "standard" metric as well. European metric, not Asian.

[38_Cal]

And then I ran across a 1/4-26 the other day. Not an ancient screw...it was a forend screw for a British BSA International Mk II Martini rifle, which started production in about 1955. None of my "special" series tap charts even mentioned that size... I was fitting a new barrel to this rifle, so I just made a new screw to match the dimensions of the original, except for it being 28 tpi. Easier for me, and cheaper for my customer, than trying to come up with the "proper" tap!

David

[oldtiffie]

Originally Posted by mardtrp
Oh the joys of playing with that outdated MONGREL system , it's about time you lot converted to the easiest system of them all, metric.


Mark

yep, the system with 5 different possible pitches for an M12 (or is it M14) screw........

And the "standard" pitches differing depending on which country the screw is from.....

And the 4 selectable gears on the thread dial...... with the little book to tell you which to use, unless its one of the oddballs

Yah, metric isn't standardized, it's just standard....... And just as standardly effed up as "imperial".

Besides, teh 3/16 size is ancient, non-standard, and incompatible with modern ones....... It dates from before the time 130 years ago when the US officially converted to Metric.

I DO have taps and dies for 3/16, and for #12, and some other oddities

And for "standard" metric as well. European metric, not Asian.

Here JT.

Stop your moaning.

Be happy.

Set it to music.

Lots of tempo and even the meter/metre has fractions:
http://en.wikipedia.org/wiki/Meter_(music)

Now watch the pretty arm on the metronome .................

http://en.wikipedia.org/wiki/Metronome

......... and you will feel sl-e--e---p----y and r-e--l---a----x and fall to s-l--ee ..........................

z-z-z-z-z
-z
-z
-z.

So have a few "zeds".

Its a lot more peaceful than you banging that "metric" drum!!!

[John Stevenson]

yep, the system with 5 different possible pitches for an M12 screw........

Ok take the imperial equivalent of 12mm as being 1/2"

In 1/2" and I have just checked my tap list you have 12 tpi, 13, 16, 18, 20, 24, 26, 30, 32 and 40

Now ask for a 12mm bolt and 90 % of the time you will be given a 1.75 pitch bolt, the other being specials.

Out of the 10 threads I have listed for the 1/2" which one is standard ?

.

[John Stevenson]

And then I ran across a 1/4-26 the other day. Not an ancient screw...it was a forend screw for a British BSA International Mk II Martini rifle, which started production in about 1955. None of my "special" series tap charts even mentioned that size..

David

1/4" x 26 is a standard BSF size just as you have UNC and UNF we have BSW and BSF.

Seeing as it was for a 1955 British rifle it would fall into the right size and era.

You need new tap charts that show countries other than the USA.

Neil Armstrong WAS NOT the first American to go abroad.

.