Graphic surgery on a sparkling green drum

[Seth Dolcourt]

Despite the promise of copious medical gore, there is none. But promise fulfilled, I will literally take a saw to a commercially made drum shell.

The story is, I was contacted by the owner of the bubinga drum kit, who knew a guy that wanted to have his kick drum shortened. See, big kick drums make big booooooooms. Lots of resonance, lots of attention, and big kick drums look great in magazine ads. Just look at any fitness magazine (the guys have big biceps, let's keep it friendly) and you get the idea that selling sizzle with the steak applies to musical instruments, too.

As drummers refine their playing a little more, the big cannons start showing some sonic warts. A big kick takes just a split second longer for the wave from the batter side of the drum (where the pedal-actuated beater strikes the head) to the resonant side of the shell (wot points at the audience, and resonates.) By shortening the shell, the drum has the feeling of being faster, where the reso head responds more quickly. The sound is balanced, with less booooooom and more thuMP.

So my customer wanted to bob his kick drum, taking a 22" diameter x 20" long shell down to about 14" in length - a 30% reduction. For those keeping track at home, Mr John Bonham of Led Zeppelin was famous for a 26" dia x 14" deep shell, and a short kick didn't hurt his music career at all.

So, let's get started.


Our project drum. He's a big fellah. 6 plies of maple.

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This is the drum in its "war" position. Spurs extended, and the resonant head of the drum (resplendent with the Ludwig logo) looking viciously at the audience, as vicious as a green, sparkly drum can possibly look. The surgery will take place at the reso side of the shell, I'm not going to cut the batter side at all.

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Everything comes off the shell.

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Ya know how sometimes a big, furry dog looks all skinny when they're soaking wet during a bath, and the hair is matted down? No. This is still a big dog.


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Best move of the project. After removing all the metal, I gave a good inspection to the shell, and photo-documented any prior scratches and dings. Before doing any work, I emailed the photos to the customer. It's a little touch that I think will save big aggravation later.

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Laying out the lines for where to cut. The two heavy lines represent 14" and 15" lengths. I'll get somewhere between there.

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[Seth Dolcourt]

The project rolls onward.

There are better and smarter ways to grasp a shell, I did not have that available. I clamped the shell to an upright, and threw some towels under the cantilevered end. It worked out. Using a Japanse pull saw, I will cut through the lacquer and metal flake, and develop a cut line that circumscribes the shell. When it's too awkward to cut, I'll release the shell, rotate it, and continue the cut.

I targeted to remove 5.5".

Second smartest thing I did before cutting was mark my lines for lug and spur holes. Guaranteed that the new holes I drill will be in the exact position as the old holes, seeing how the section I'm cutting off has all the holes!

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Just another view of the madness.

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Making progress, you can see the thin line of the saw kerf. The clamp interferes somewhat with cutting, so there are small sections in the line that are not cut. No problem.

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I sling the drum on a 2 x 4 clamped to my bench, and complete all the cuts.

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Two dis-equal twins. Like Danny DeVito and Ahhhnold Schwarzenegger.

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This gizmo holds my router in a point in space, and I rotate the shell under a standard two flute straight bit. The un-evenness of hand cutting is replaced by a nearly dead smooth edge. I use a climb cutting technique to minimize splintering. Half the cut follows the outside of the shell, then I rotate the shell in a climb cut direction to route form the inside of the shell. The cut is not very deep, maybe 1/8" of bite, and the prospect of the router grabbing the work is not an issue.

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A maple stave, faced with cork and 150 grit sandpaper, makes an excellent sanding block to remove any tool marks.

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[Seth Dolcourt]

And we roll on.

I've not documented the part of making chamfers in the edges, a small chamfer on the outside of the shell, and a much larger on the inside. But the chamfers form a peak, about 1/16" wide, and that is the bearing edge that the drum heads seat upon. I matched the original factory profile.

The shell on my drilling station (a 2 x 4 clamped to the workbench), ready to drill. The 2 x 4 is somewhat contoured to the inside shape of the shell, and acts as a backup to prevent blow out.

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Story stick. I have 10 sets of double holes to drill, and I'm too lazy to mark each and every one of them. So a story stick captures the set-back and the hole spacing. I insert a 1/4" brad point, and make a dimple. Wash, rinse, repeat at 10 locations, it's done in a short amount of time.

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In progress of drilling for the lugs.

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This drilling template is for the spurs (legs). Make the template just right, and the drilling will be spot on. I have 4 points to drill, and accuracy matters.

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All the drilling is complete, time to take off the tape and clean it up. Then the lugs and spurs go back on.

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The grafted together shell, showing with good clarity the proportion of the original full size compared to the cut size.

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The shell, with the off-cut. The customer owns the off-cut, even though it's useless.

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Heads and hoops in the background, I'll let the customer install them and tune the drum to his liking. He installed, tuned....and liked. Less booooom and more thuMP. Thanks for looking!

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[Stephen Cherry]

Thanks for the writup Seth- for the cutoff, I would recomend making a giant tamborine.

[Seth Dolcourt]

Hi, Stephen,

That would be a big-dog tamborine! Cool suggestion, though.

[Nauman Shafique]

Neatly done! I really like the color of this drums though. The sparkling green is simply elegant and eye-catching. And the idea of a big-dog tambourine is really interesting. Make sure you post about it if you ever plan on making one.

[Julie Moriarty]

This is really an education! I've never even thought about timing sound resonance through a drum, let alone cutting it to fine tune it. Thanks for the education, Seth!

I enjoyed the pics and seeing the little notes you left for yourself on the blue tape. Always good to have reminders.