Radial Bridge Pro Drums

Not so long ago, I was approached by a guy named Tony. Tony initially described himself as a drummer, which is about as accurate as describing your car as a tire. There’s way more to the guy. Being a drummer is just the facet he thought relevant at the time. (He was right). Tony’s story revolved on his deep affection for a particular type of drum, invented by a guy named Steven Volpp, made for a time by Peavey, and discontinued. Like many things in the modern age, there are now facebook pages, forums, etc to cater to the remaining die hards of this niche market.

But it piqued my interest. I’m big on music. My life wouldn’t be the same without it. I’ve played instruments from violin to viola, cello, trombone, tuba, a tad of really horrific piano… no, I don’t sing. And the world is glad for that.

Long story short, Tony wanted, REALLY wanted, someone who could figure out how to make, or re-make, these drums. What follows is a trip down that lane. I’m going to talk like a woodworker, so if you’re a drummer, forgive me. I’m probably not going to get all of your jargon down pat.
The thing that sets the radial drums apart is the way in which the heads attach, specifically what they attach to.

Take what you know about wood, strength, flex, movement, all that, and make a drum. Now wait, you’ve got to attach metal heads to it, and the thing has to stay together. Well your shell, if you’re basically every drum manufacturer out there, just got really thick, and you bolt all these blocks of hardware to it, and then the metal hoops are held on with bolts that go through the hoop and down into this, I dunno. Bracket. Lug. Lets say lug. I like that word.

To me, you just kind of killed part of the drum. The shell is what resonates. Not only did you punch holes in it, you bolted things to it which are going to dampen it. And it has to be sufficiently thick not to turn into an oil can under the tension. Maybe I’m wrong, but Tony’s description of a bridge piece that held the stresses, resulting in a very thin shell, struck me initially as an idea with legs.

2015-05-12 07.43.07So the very first thing I did was get to play with one he had. This one had a plywood bridge. Unattractive, but it works. I cut the shell down, got to see how it was all put together, took a lot of measurements, and started making a game plan.

The nice looking ones are made out of maple. The bridges, that is. The shells are sourced by a company named Keller. Honestly, they’re tight. I’ve concluded by now that they have their collective s##t in a straight line over there, because the tolerances are super tight, and super predictable. Their seams are almost invisible. Good stuff.

To start making one, first you have to understand the profile you’re creating, in radius form. The inside of the bridge has a rabbet into which the shell must fit. Just. Slop here to me is a deal breaker. This joint needs to squeak when pressed together. The shell OD is 1/2″r larger than the ID of the bridge. Exactly. The Bridge OD is 1 3/4″ larger than the ID, radiused. Lets make this easy and just look at a cross section.

RadialPro

That whole shape is cut into a blank that begins life as an octagonal glue up of very thick maple. Bear in mind, while its not so hard to find 8/4 hard maple, this finishes at 2″, so to get the stock you need, you’re going to have to find at least 10/4, perhaps even 12/4. The number of mills around willing to even try to cut that and dry the stuff is limited. The ones that are able to keep the boards from self destructing in the process, well, you’re going to pay for it. And probably truck it 800 miles to get it. Mine was just sitting in a warehouse in Chicago waiting to hear from me. At least I found some.

Maple in hand, you’ve got to map out what the octagonal pieces have to look like, select the stock, and start squaring. I learned on the first one that if you do not take the time to get everything dead square, you might as well just forget about it. I made a lot of really pretty firewood at some points along this journey. Beginning with stock right off the ripsaw was firewood moment #1.

drum16So here’s the Sketchup drawing I do at the outset. This one is for a 16″ shell. I’m laying out the ID, OD, and where the rabbet is. Then choosing a size of octagon where the blocks allow for that to come out. So all of these started as 2.25×3″ stock.

Then you cut the 22.5 miters, and start fitting.

Note: no strap clamp in the world is going to pull together this ring if every joint does not fit perfectly.

That kind of stuff works ok sometimes on thinner stock. Enough pressure, you can forgive a half degree of slop in an assembly like this. Maple that thick, it’s got to be dead on, both on the miter, and the 90deg to the face cut.

How I finally settled on getting there: I dismantled the saw partially, used squares, machinists calipers, and a digital protractor to tune the saw as close to dead on as it would let me.

Then I marked a face of each board. This line simply shows a face. The stop block is set, and the board is flipped back and forth along its length making the cuts. When it comes to assemble, line up, line down. This keeps the grain from all going the same direction AND any slight irregularity in the cut evens itself out.

Until you try to close the loop. Invariably, I would have a piece or two I just wasn’t in love with, so used whatever the situation called for there. Sometimes it was a sanding block on a sled. A lot of time, it was a shooting board. Ever tried to shoot 2″ of end grain maple? Yeah.

IMG_0414[1]If you don’t know what a shooting board is, it’s just a jig that lets you run a plane on its side so as to trim end grain. This is an example, on thinner stock.

So, glue it up. No, wait. Worried that this wouldn’t be strong enough, I laid out locations to reinforce the joints with dominos. This is a Festool invention – loose tenons, like dowels, but stronger, and more accurate. Just have to make sure and put them where subsequent cuts will not expose them. Just have to make sure and put them where subsequent cuts will not expose them.

 

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Once the rings are glued up:

To clamp them, a strap is a good start, since it does a decent job of restraining the tendency to slip. Then clamps can be placed across 4 ways, tightening slowly and together, watching the joints to make sure that tightening one spot is not opening another. Then they go through the wide belt, and I bring them down to flat at about 2.1″ thick with 80g, and then 150 for a couple passes to about 2.05.

Now we can cut. ID first. As I worked through this process, this order is what made the most sense and produced the best results. The ID pattern is a big ring, 1/2 clear plexi (as are all the patterns, CNC cut) that screws to the top of the bridge, where the waste is. The ID is routed first with a carbide spiral and a bushing, then finished with a patterning bit. Oh yeah, MARK arrows on the glueup so you can keep track of up and down. The dominos are set at the bottom.

Then the bottom gets its rabbet, 1/2 x 1/2. Probably the easiest of all the steps. This ID pattern is just a hair tight, so that the rabbet is just a hair tight, so that each shell can be hand fit into the bridge.

That’s the next step. How I’ve been doing it is mounting the shell at this point on the lathe using bowl jaws.
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While I’m not using gouges to cut, it holds it centered, and I can use card scrapers and paper while it’s running until I’ve taken just enough I can get the shell in. This pic in particular shows the limitations of the lathe. For a 20″ shell, the bridge won’t go over the bed. So it went outboard with the head flipped around, and then I had to make a pattern to hold it since the bowl jaws don’t go that big. Hey, it worked. And I am never taking that faceplate off the back of that pattern.

Once the shell fits, the next piece of pattern is called the filler. This is identical in dia. to the rabbet / shell, and has brass index pins in it which allow it to snap onto other pattern pieces. It stays in the bridge (and supports the thing while cuts are happening) and other patterns then register to it.

The OD pattern indexes off the FILL pattern. This can be done with a hand router or an overarm router. The real challenge here, if there is one, is getting a bit long enough to make the cut, taking the cut slowly enough not to blow the ring apart, and getting a clean cut. If there were a power feed that fit on the overarm router and worked on radius work, man, I’d be sold. As it is, each time you go around, its constantly changing grain direction and white knuckles. I like the overarm router for what it does, and how well it does it. I hate how attentive I have to be not to throw 8 hours of work 100 feet across the shop. Or the bloody knuckles that invariably result from that sort of thing.
Moving on.
2015-06-12 14.40.09With the ID, OD, and rabbet done, there’s some waste to remove at the top outside. Lots of ways to do it, but on a smaller shell, the dead simple way is back to the lathe and the bowl jaws and just cut 90% of it off with a gouge. On bigger rings, there’s too much flex that far from the spindle to get a clean cut on this, so it’s all the overarm router. So hang on with two hands, run the foot pedal, keep one hand on the speed brake, the other one on the depth stops, oh yeah. Four hands. Wouldn’t that be great some days.
So here, pattern up, you want the recess to leave exactly 1″ of meat at the bottom. All the way around. Downcut spiral, keep the blank tight to the table. If it jumps, that’s a firewood moment.

The radius work is done on a router table, and is simple and straightforward.

The chamfer inside is as well. Not quite as easy, because what you really want is a wire edge. Most chamfer bits are real small, and this needs one with some cut capacity, so I use a big Whiteside thing with about a 2″ edge, and take it up about an eighth at a time until I’m right there with about a 32nd of a flat at the top.

When everything is cut, its back to the lathe and bowl jaws.

This is how I sand everything down. I use card scrapers to remove scratches or the errant tool mark. Radiused blocks to keep the inside smooth.
The last pattern lays out the holes for the lug inserts. These work just like a split saw nut, except they’re hollow and threaded inside as well, for the bolts. This pattern just clamps in place, and a striking pin creates an indent.

A little challenge here, you’ve got to get the holes all the way through, and straight, so that everything lines up. I’ve settled on piloting with a 5/32″ bit, in the drill press, multiple shallow cuts or the bit will walk sideways through the wood before it exits. Then the 15mm forstner, recess for the nuts, at .23″, then the through hole at 13/32″.

Last thing to do is mount the shell, which is a thin bead of glue, a couple clamps to hold things together, and a little sweat equity getting the shells to slip in and seat.
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All in all, the process trips my trigger. It’s got music, details, and frankly, it’s not another square plywood box. It is deceptively challenging to pull off. One looks at the simple ring at first, sees the obvious octagonal construction, and thinks gee, that can’t be hard. Well, no. If all you had to do was make something that looked like that, you could do it in a couple hours. But to do it right, to make the joints tight, to get the dimensions dead on, to make the shell fit, and moreover, to make this whole process predictable, repeatable, and clean enough that you can live with yourself, yeah. The detail level to me is right there with doing inlays. Its a lot of fuss and muss over minute details, and I kind of like that. So far, this will certainly not be the source of my retirement. I understand completely how, in a manufacturing environment, this whole concept just does not lend itself to mass production. It would be expensive, generate a lot of waste, be difficult to continually source adequate materials, and have to sell at a cost that would put it way above many of the other offerings out there. I get it. Limited market. But I’m ok with that. I’ve never mass produced much of anything, and my best customers know what they want, and have at least a basic understanding of what it actually takes to get there.

When Tony approached me at first, I don’t think he had any visions of grandeur regarding the market. Sometimes these come up on ebay. And certainly less than what anyone can make them for. But there will be times when what someone wants, it just isn’t there. Now I kind of look forward to adding this to the list of things I’ve got figured out.