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Fixing Bent Rims
by
Ned Ingberman
Throwing
a wrench into the works isn't always a bad thing. In the case
of a bent drum rim, it's the way to straighten things out.
With wrench in hand and the aid of this article, you can remove
unsightly bends and restore a rim to its original contour.
Of
the many shapes and forms rim damage can take, the most common
is the inward-protruding bend. This occurs in the upper area
of the rim above the bearing edge of the drum and protrudes
toward the drum head. In this article, we'll focus on how
to restore this particular kind of rim bend in non-cast flange-style
vintage rims.
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Note: some rims have an inherent irregularity
in the shape of their joint. This irregularity can be distinguished
from a dent by its rippled or wavy appearance which may extend
into the rim flange. In such cases, it's best to leave it
as is. Any repair attempt can crack the weld of the joint.
To
get started here is a list of tools and supplies you'll need:
•
Adjustable 8" Crescent®-type
wrench
•
Metal shim plate, 1-1/4" x 1/2"
x 1/8"
• 1-1/2"
x 1-1/2" piece of non-corrugated
cardboard - 1/16" thick
•
Masking tape
The
first step is to customize your wrench. Cut a piece of cardboard
the size of the contact surface of the adjustable lower jaw
of the wrench. Then use the masking tape to bond the cardboard
tightly to the lower jaw's surface. The cardboard buffers
any metal to metal contact between the lower jaw and rim which
could otherwise mar the rim.
The
metal shim plate also buffers the rim from being damaged by
the wrench and helps to realign the rim's vertical profile.
If you don't have a ready made shim plate, cut a 1-1/4"
section of metal from a 1/2" strip
of 1/8" thick stock. An excellent
source of metal stock is a leg or leg support section of a
defunct flat base vintage Ludwig hi hat, cymbal, or snare
stand. Metal stock can also be found at a good hardware store.
After the shim is cut, file away any sharp edges or burrs
and be sure all surfaces of the shim are perfectly smooth.
Lining
Things Up
Unlike
many restoration projects which require a damaged component
to be removed from the drum before it's repaired, a bent rim
is best left mounted on the drum. This anchors and stabilizes
the rim to prevent it from shifting or flexing as pressure
is applied by the wrench. Be sure all tension rods are snug.
Then position the drum horizontally on a table so that you're
facing the inside wall of the bend.
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Next,
position the broadside of the shim horizontally alongside
the outside wall of the bend (see Figure 1). Line up the midpoint
of the shim with the extreme point in the bend (i.e.: where
it is most protruding inward.) Also, be sure the long edge
of the shim is resting on the rim flange below it. Holding
the shim in place, position the fixed upper jaw of the wrench
flush against the midpoint of the shim and tighten the adjustment
knurl so that the lower jaw is squeezing the extremity of
the bend. Adjust the position of the wrench so the lower jaw
is close to or touching the drum head. To firm up the grip
of the wrench, gently jiggle the handle forward and backward
while simultaneously tightening the knurl.
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Figure 1
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If you have a Ludwig-type triple-flange rim, and the drumhead
is either stretched out or has a deep collar-causing the drumhead
hoop to extend fairly low over the edge of the drum-you may
need to replace the head with one that has a shallower collar.
This will bring the rim up higher above the drumhead, allowing
the wrench to get a better grip on the rim. Otherwise the wrench
can slip due to the curved edge of the rim's upper flange.
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Removing
The Bend
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apply forward pressure on the wrench handle while anchoring
the drum with your alternate hand. As the wrench handle moves
forward, the section of the rim between the jaws will straighten
up. To gauge how far forward to move the wrench in order to
restore perfect perpendicularity, adjust your line of vision
so your view is from above (see Figure 2). From this vantage
point it will be easy to assess the vertical profile of the
rim. |
Figure 2
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Since most bends span a width greater than the jaws of the wrench,
multiple wrench applications are usually needed. For best results
when re-applying the wrench, position the lower jaw at the periphery
of the section of the bend previously straightened. Continue
to monitor the perpendicularity of the rim between wrench applications.
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If in the process, the wrench is extended too far forward,
it will misshape the rim causing it to bend outward. This
can easily be rectified. First, using the remainder of your
cardboard supply, create another shim by folding the cardboard
three layers thick. Then position the broadside of the shim
horizontally against the bend on the inside wall of the rim
with the shim's long edge against the drum head (see Figure
3).
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Figure 3
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Holding the shim in place, position the lower jaw against
the extremity of the bend and tighten the adjustment knurl
until the upper jaw is squeezing the shim. Firm up the grip
of the wrench as described earlier and be sure there is clearance
space of about 1/8" between the tip
of the upper jaw and the drum head. Then slowly move the wrench
handle inward until the rim is perfectly perpendicular.
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The last step is a touch test to confirm the rim's straightness.
Place your fingertip against the inside wall of the rim at
a point two inches away from the repaired area. In a continuous
motion, slowly rub your finger into, across and two inches
beyond the repaired zone. As your finger moves across the
rim, you should feel a smooth continuity in its curvature.
Restoring
the original contour of a rim is not likely to improve the
tone quality of your drum, but it will certainly enhance its
beauty - and musicians, like all artists, have a special relationship
to beauty. A noted Polish poet, Cyprian Norwid, once wrote,
"Beauty is to enthuse us for work, and work is to raise us
up."
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