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.
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--- Black Holes are where God is dividing by zero ---