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.
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.
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.
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.
Removing The Bend
Slowly 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.
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.
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.
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.
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."
Interested in Ned's restoration consultation services? Please check out his site at http://www.vintagedrum.com/restore.htm.