On Fri, 19 Jun 2015 08:01:44 -0400, "Jim Wilkins"
wrote:
"John B." wrote in message
.. .
On Fri, 19 Jun 2015 18:15:00 +0800, Techman
wrote:
I need to replace a broken light duty torsion spring and need some
advice.
It's broken right at the bend, I may be able to buy a new one but it
will have to come from the UK to Australia and I need it ASAP.
https://dl.dropboxusercontent.com/u/...ring%20(1).JPG
https://dl.dropboxusercontent.com/u/...ring%20(2).JPG
The spring returns an aluminum flap through and rotates through an
angle
of around 90°.
The wire diameter is 4.5mm and the overall length of the spring is
around 24".
I can get some 3/16" diameter "piano wire" (4.76mm) or 5/32" (4mm)
from
my local hobby shop. Will piano wire work OK as a spring in this
sort of
application?
Will I have trouble cold bending the ends?
I was thinking of drilling a 5mm hole through a heavy piece of metal
and
using pipe, then a hammer, applying the bend. I would try to leave a
more generous radius than the on the original.
Thoughts?
Thanks guys.
I've made a number of springs from music wire and they seem to work
pretty well. and yes, a bit more generous radius on the bends will
probably last longer.
I would think that you could bend 3/16" by hand, or perhaps a couple
of pairs of pliers, so a fancy jig shouldn't be necessary, and I
wouldn't hammer on the bends as it might work harden then even more
and could cause them to fail.
--
cheers,
John B.
3/16" steel welding rod can be bent by hand, but the work hardening at
the bend stiffens it there and causes the whole piece to curve rather
than allowing a tight localized radius. When I need a tight U bend
with straight legs I have to rubber-hammer the rod around a mandrel.
AFAIK music wire is hardened by cold drawing and doesn't respond to
heat treating as well as you might like.
-jsw
Will, firstly, the guy was asking about 90 degree bends in 3/16" rod
which if you cannot make with your bare hands and maybe a couple of
pairs of pliers sort of implies that there is something wrong with
you.
Out of curiosity I just went out to the shop and bent a piece of 5.5
mm (0.216") rod and had no problem what so ever bending a nice 90
degree bend with about a 1/4" radius.
--
cheers,
John B.