Lew Hartswick wrote:

Grant Erwin wrote:

For years I've considered spring-mounting things, but I've always hit
this fundamental barrier: I didn't want to use a through bolt, and I
didn't know how to fasten a spring to a flat surface by one end. Well,
now I have to solve this problem, and I got some suitable springs and
did a cut/try until I found what works, but it's sort of like making a
1/4-20 nut, lotta work for something you can buy for 3 cents.

Although you can't see it, here's a picture of one of my compression
springs bolted tightly to a fender washer:
http://www.tinyisland.com/images/temp/springNut.jpg

I'm wondering if there is an elegant solution to this problem, or if
there are stock nuts made to do this job. If there are, I can't find
'em, but it could be a case of I'm not looking for something by the
right name.

Anyone?

GWE


It's not, as my former boss use to say, "intuitively obvious" what is
inside the spring to screw the machine screw into. How about an
"exploded" view?
...lew...

It's sort of shaped like a porkpie hat. The "brim" is as wide as the OD of
the
spring, and the "hat" part just fits into the ID of the spring. The part is
drilled & tapped axially. About 240 degrees of the "brim" are cut away. The
entire "hat" is about .010" thicker than the space between the spring
windings,
so it needs to be forced in between, so it snaps in satisfyingly. You snap
it in
and then "thread" it down the spring helix until it jams at the end. At that
point you can tighten a machine screw into it. The "hat" needs to be tall
enough
so it holds 3 full threads, and the "brim" needs to be thin enough so it can
be
coerced into turning to 120 degrees from the end of the spring wire. The
spring
retention nut I designed will only sit square to the spring axis if the
spring
has a square end (i.e. if the helix angle of the spring tightens up at the
end).
The nut sits inside bearing on the part of the spring wire that is square to
the
spring axis.

I can't really photograph it and do it justice, my explanation is going to
have
to suffice.

I'm surely not the first one to do this. And I have to make 12 of 'em. I was
hoping to find a commercial product, or something that is easier to
fabricate.