Discussion Forum

How to insert a #4-40 SHCS

To add questions or replies, please log in.



Filter:

Post author:
Text in post
Post date from: to: (dd.mm.yyyy)
 
How to insert a #4-40 SHCS
I'm not familiar with ANSI, DIN, etc. I looked through a variety of things and could find ANSI B18.3 but it seems to start at 1/4".

Are there any standard parts for numbered screws, like 2-56, 4-40, etc.?
community additions..
I've done this myself manually. It takes a little digging but it's not that hard. Here's how I get a 8-32 SHCS:
Open up the file /opt/Varicad/bin/glib/ansi/screws/scr6a_a.pdt
You'll have to be root for that or find it on other systems. It's the definition file for B18.3 inch threads.

In section <select> just above 1/4, add 8-32 (it doesn't seem to like #8)

In the section <data> above 1/4, add:
8-32
0.164
0.25 0.5 0.75 1 <>
0.25 0.5 0.75 1 <>
0.270 0.138 0.141 0.09
0.1248 0.1437 0.03125 0.1875
0.313

The format as far as I've deduced is:
name
basic diameter
screw_length_1 screw_length_2 screw_length_3 ... delimit (<>)
threaded_length_1 threaded_length_2 threaded_length_3 ... delimit (<>)
head_diameter head_height key_size key_depth
thread_minor_diam thread_basic_pitch_diam thread_pitch through_hole_size
counterbore_size

thread_pitch is expressed in inches, so 1/32 in the above example. For each screw_length there must be a corrosponding threaded_length.

Somehow it figures out the correct thread in 3D. I'm guessing by basic diameter and pitch rather than the name. Also Varicad seems to dynamically reload the file so you don't have to close the program if you make changes to the file.

Don't forget to backup your new and old files as updates will overwrite them. It would be nice if this were documented even a bit. One day I'll work on pipe threads which are sorely missing.

If you do this for 4-40, please post back here so we all can C&P it into our files.

1