A broken spring is what often brings a customer
into my shop. Replacing them is tricky, and here is what you need to
know to do the job right.
Flat springs, as used on palm and side keys, are
pretty much a no brainer. Replacements are available in blued steel,
stainless steel, and bronze. I find that the stainless ones are too
soft for anything but flutes and clarinets, and use bronze ones
where that material was original equipment (as on the Mk VI) and the
blued ones at all other times. The blued ones are generally much
stiffer.
To replace a flat spring, first remove the key
and apply some penetrating oil to the screw that holds the spring in
place. Set the key aside and carefully clean the track that the
spring contacts on the body. I use a Q tip and Simple Green solvent
for this process. Next, cut a small strip of Teflon exactly the same
size as the track, and glue it into place with E6000. The Teflon
will allow the spring to operate freely, and you'll be delighted
with the results. On some horns (Kings particularly), there is a
stop at the end of the track. Don't let the Teflon cover this
vertical piece! Next, remove the old spring by backing the screw
out. These screws are VERY tiny, so keep a magnet handy to pick up
the ones you drop on the floor. Select a replacement spring that
matches the THICKNESS of the original. Length is unimportant, it's
the thickness that matters. If you don't have one that is thick
enough, you can use two thinner springs laid atop one another. Be
sure that the hole in the spring is large enough to receive the
screw, if it's not, then carefully open it up with a small reamer.
Reinstall the key on the horn and note the required length of the
spring. Take the key back off, and cut the spring to a length about
1/8 inch longer than required. Gripping the spring with a pair of
needle nosed pliers, bend the excess length up so that the contact
point with the body of the horn is smooth and does not dig into the
Teflon. Reinstall the key on the horn and check the tension. You can
adjust the tension by bending the spring (avoid sharp kinks) away
from he key to increase, towards the key to decrease.
Broken needle springs are the largest single
source of high blood pressure and strong language among repair
technicians. Improper removal of broken stubs can seriously damage
your instrument. Here's what to do:
First, give yourself plenty of working room (you'll need it) by
removing all keys surrounding the broken spring. Clean the area
around the broken stub, and apply some penetrating oil. Carefully
note the condition of the stub. If there is enough exposed material
to grip with a pair of needle nosed pliers, you must have been
living right! Grip the stub with the pliers and give it a good
wiggle. Does it move? if so, carefully work it out of the post. If
it doesn't, apply some more penetrating oil, heat, and wait before
trying again. Don't try to force it! You will bend the post, and
that will not be a happy time in your life. If the spring doesn't
move, and there is some exposed stub, then try giving it a squeeze
with some spring installing pliers from Ferree Tool. This will
usually do the trick. If this doesn't move it, then you're going to
have to drive it out. Not a happy time. Cut any exposed stub off
flush with the post. Then take a large needle spring and cut a tiny
portion off the tip so that you have a flat surface. Select a small
hammer, and after placing the end of the large needle spring against
the stub of the broken one, begin tapping, always remembering that
heavy blows will bend the post, and that the two springs must be in
constant contact with one another or you will permanently mar the
post. Should this process fail to remove the stub, after a suitable
period of strong language, you're going to have to unsolder the post
from the body of the horn. I'll assume you know how to do this, and
if you don't, take your horn to someone who does. With the post off
the horn, and carefully noting the direction in which the stub must
be removed, drive the post slightly into a lead block so that it
does not move. Then take the large needle spring prepared earlier
and give it a couple of manly whacks. This will remove just about
any frozen spring.
Now that the stub of the old spring has been
removed and once your nerves have settled down from the removal
process, select a replacement of the same type and diameter as the
old one. Blued springs are stiffer, stainless steels don't rust but
are softer, and piano wire (used on Buffets) works just like the
other type. Insert your new spring into the hole and make sure it
fits tightly. If it wiggles, it's too small. Beware of oversizing
the springs by increasing the hole diameter. If the spring is too
big, the action will feel sluggish. Once you have figured out the
correct length, bend the spring at a point flush with the post so
you know where to clip it. Cut the spring and remove it. Place the
end on your jeweler's anvil and give it a couple of whacks with a
hammer to slightly flair the end. Don't heat the spring to soften
the metal to facilitate flaring: this will cause the spring to lose
its temper, and it will not be strong enough to do the job. Pull the
spring through the hole with a pair of needle nosed pliers, and make
sure that it fits tightly. Reinstall the key and feel the tension of
the springs on the surrounding keys. Adjust the new spring by
bending with your fingers in an even arc. Take care not to put a
kink in the new spring as this will shorten its life. That's really
all there is to it. Email
me your questions, and good luck!
