John2005 wrote:
...snip
I would like to ask if anyone could please provide some feedback on the
following situation.

I have a 3/8" diameter steel rod that is threaded horizontally into a
vertical steel support at one end, and that has a moderate vertical
load applied to the rod at the other end, 5" or 6" from the support.
The load tends to deform, pry or bend the threads out of the support.

The threaded end of the 3/8" rod necks down to a 5/16 diameter by 24
pitch thread, and the necked down portion that the threads are applied
to, can only be .183" long Maximum. The actual threads won't quite be
.183" long because they probably cannot go completely flush to where
the rod necks down.

The threaded end of the rod is screwed into the steel support until it
bottoms out, right where the rod necks down...

(3/8 - 5/16 = .0625 / 2 = .03125) so there is a 1/32" wide portion of
the rod OD that bottoms out on the steel support.
...snip

If you look at the rod as a lever, the fulcrum is the bottom edge of the
3/8 section that bottoms onto the vertical steel support. When the
vertical load is applied to the end of the rod, say 5.5" from the
fulcrum, it is resisted by a horizontal axial load only 3/16" (.1875")
from the fulcrum (its not really 3/16", but you get the idea). Doing
the simple maths, the horizontal force is then 5.5/0.1875 = 29 times the
vertical load. If you weld a 1" diam steel collar to the end of the rod
where it buts against the steel support, the horizontal load is 0.5"
from the fulcrum and is therefore reduced to 5.5/0.5 = 11 times the
vertical load. This way the horizontal load on the thread is reduced
considerably.

--

Regards, Gary Wooding
(To reply by email, change feet to foot in my address)