Hi Knowledgeable Folks;

I am doing a design and need to know what difference there is between a
10-32 thread and a 3/16-32 thread. The seem very close on OD, they use the
same pilot drill, 5/32" and they obviously have the same thread pitch.

So, any info on this? If there is a difference, could you be specific
please, especially about which is bigger?

Thank you, Tom Kay, Ottawa Canada.

They are the same. The nominal diameter of #10-32 is.190" but most of the
screws that I have measured are a few thousands under sized.

Kent

"Tom Kay" wrote in message
...
Hi Knowledgeable Folks;

I am doing a design and need to know what difference there is between a
10-32 thread and a 3/16-32 thread. The seem very close on OD, they use the
same pilot drill, 5/32" and they obviously have the same thread pitch.

So, any info on this? If there is a difference, could you be specific
please, especially about which is bigger?

Thank you, Tom Kay, Ottawa Canada.

In article , Tom Kay wrote:
Hi Knowledgeable Folks;

I am doing a design and need to know what difference there is between a
10-32 thread and a 3/16-32 thread. The seem very close on OD, they use the
same pilot drill, 5/32" and they obviously have the same thread pitch.

So, any info on this? If there is a difference, could you be specific
please, especially about which is bigger?

The 10-30 is marginally larger (0.0025" IIRC). However for a
new design, I would suggest that the more important feature is that
10-32 is a current standard, while 3/16-32 is an obsolete standard, so
it will be more difficult to source screws at present, and become more
so as time goes on. (This is in the US, of course. In Canada, you
might want to look for the nearest Metric size, unless your target
market is the US.) Perhaps a M5, which would have a diameter of
0.1969", instead of the 0.190" for 10-32, or 0.1875" for 3/16-32.

Best of luck,
DoN.
--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

A 3/16 screw would have a nominal diameter of 3/16 = 0.1875 inch; whereas a
#10 screw diameter is [ 0.060 + (10 X 0.013) ] = 0.190 inch. As you said,
they are pretty close, about 0.0025. AFAIK, 3/16-32 is not a standard
machine screw.

Bob Swinney
"Tom Kay" wrote in message
...
Hi Knowledgeable Folks;

I am doing a design and need to know what difference there is between a
10-32 thread and a 3/16-32 thread. The seem very close on OD, they use the
same pilot drill, 5/32" and they obviously have the same thread pitch.

So, any info on this? If there is a difference, could you be specific
please, especially about which is bigger?

Thank you, Tom Kay, Ottawa Canada.

Bob Swinney wrote in article
...
A 3/16 screw would have a nominal diameter of 3/16 = 0.1875 inch; whereas
a
#10 screw diameter is [ 0.060 + (10 X 0.013) ] = 0.190 inch. As you
said,
they are pretty close, about 0.0025. AFAIK, 3/16-32 is not a standard
machine screw.

Bob Swinney

A number of years ago, a machinist friend of mine gave me the formula for
numbered screws, and I lost it.

I cannot remember why I was looking for it recently, but I simply could not
find it anywhere - even in the 25th edition of Machinery's Handbook
(although I suspect it is in there and I simply wasn't looking in the right
place).

I have printed it off, and tucked it away in the "formulae" section of my
"Bob's Big Book of Stuff" looseleaf in the shop.

Sometimes, when you try to help one person, you will also help another in a
totally unrelated way. This is one of those examples.

Thank you for posting the formula here..

Bob Paulin - R.A.C.E.
Racing Chassis Analysis Services

In article 01c40238$402f91e0$31a0c3d8@race, Bob Paulin wrote:


Bob Swinney wrote in article
...
A 3/16 screw would have a nominal diameter of 3/16 = 0.1875 inch; whereas
a
#10 screw diameter is [ 0.060 + (10 X 0.013) ] = 0.190 inch. As you
said,

[ ... ]

A number of years ago, a machinist friend of mine gave me the formula for
numbered screws, and I lost it.

[ ... ]

I have printed it off, and tucked it away in the "formulae" section of my
"Bob's Big Book of Stuff" looseleaf in the shop.

Sometimes, when you try to help one person, you will also help another in a
totally unrelated way. This is one of those examples.

Thank you for posting the formula here..

If anyone wants a computer program to do the task, I wrote one a
while ago -- and just discovered a problem with the 10-32 calculations
(it was being treated as 0-32 instead), so I have fixed it.

It can be found on my web site at:

http://www.d-and-d.com/shop-programs/number-screw/

and the three files a

================================================== ====================
-r--r--r-- 1 root daemon 1051 Mar 4 18:44 Makefile
-r--r--r-- 1 root daemon 1530 Mar 4 18:46 README
-r--r--r-- 1 root daemon 4331 Mar 4 18:41 number-screw.c
================================================== ====================

It was written for unix (since that is what I use), and it is a
command-line program, not a GUI one, but a typical use would be:


================================================== ====================
number-screw 10 32
================================================== ====================

which produces the following output:


================================================== ====================
For a #10-32.000 screw:
Clearance diameter: 0.190
Tap drill diameter: 0.159
================================================== ====================

If you leave off the thread pitch, it simply gives the diameter. It
handles the sizes down to "000", and up to any size well beyond the
actual ones in use. :-)

Obviously -- you will need a 'C' compiler to make it run on your
computer. For the convenience of unix users, I include a generic
Makefile to ease compilation. It may or may not work with Windows C
compilers, depending on whose and how closely they follow unix
conventions. I suspect that the Cygwin package will handle it without
problems.

Enjoy,
DoN.
--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

"K Frazier" wrote: They are the same. (clip)
^^^^^^^^^
Just as an aside, I once stumbled across some thread tables that showed a
14-20 thread as being the same as 1/4"-20. Interesting that the number
series thread disappeared, whereas, in this case, the fraction size went
away.

From: "Leo Lichtman"

I once stumbled across some thread tables that showed a
14-20 thread as being the same as 1/4"-20.

I once stumbled across a real 14-20 tap. And used it. The holes were really
easy to tap but I had to put the 1/4-20 screws in with a sledge hammer.G

Richard Coke