A split vent snare drum is not a new concept. Two separate shell sections with a consistently spaced gap between them.
Vents in general are a common part of drum construction. They give a place for air to go once the drum is hit ... so as not to choke out the sound. The most popular configuration is one vent hole ... usually with a decorative metal grommet, but some just go with the hole in the wooden shell. Other people/companies us a two hole configuration, or make really large (2"+) holes ... I've even seen a drum riddled with holes. The larger the hole(s) and/or gap, the more air can escape at a fast rate. The drum sound becomes dry, quick decay/short sustain, and louder.
I wanted the split vent to be the primary design element ... and my very first thought was to use a zipper. Instead of the gap being consistent, it would gradually widen and give the appearance of the drum shell being unzipped.
It's always possible the visual evidence is buried deep within internet history or undocumented, but I believe this drum to be the first of it's kind ... and I looked for at least 7 minutes and 36 seconds.
Step 1: Preparing the Plywood Shell
The shell is a maple 8-ply VSS from Keller. You can buy the shells cut to your desired depth, or you can buy full tubes ... 18" or 24" deep depending on the diameter and shell thickness. I buy full tubes and cut them myself using a shop made fixture for table saw.
Once I have the fence and fixture set to my desired width, my right hand holds the shell in place and tight against the fence, while my left hand powers on the saw. The blade is then slowly raised into the shell until it is about 1/8" above the inside edge and the shell is rotated into the blade until the entire circumference has been cut. At that point, I power off the saw, but keep rotating the shell until the blade comes to a stop. It's not necessary, but I've found that this prevents any burning or minute ridges from being left on the edge of the shell. When cutting shells, I use an 80 or 90 tooth Diablo Blade.
After cutting the shell, I true it up on a flat surface with sandpaper ... this will remove any burning, high spots, etc. For a surface, some people use a glass tabletop or a granite slab .. I'm using the top of my work/assembly table. For sandpaper, some people use large sanding discs (26" diameter and larger), or buy rolls of sandpaper and attach it to the surface with spray adhesive. I tried using regular 8 1/2" x 11" sheets with spray adhesive, but the edges peeled up and it was ineffective. My current method is clamping a broken drum sander feed belt to the table ... it works amazingly well.
About the shell cutting fixture
The design is roughly based on of an old drum factory tour video I saw (either Ludwig or Gretsch). I've seen people make simple versions with conveyor rollers and even fixed, rubber casters from a hardware store, but they didn't fit my need/desire.
1. I wanted a fixture which slipped over the existing table saw fence. No need to clamp it down and it would automatically be square with the blade.
2. I wanted enough capacity for a full 24" tube so that all of the stock is supported before and after the cut.
3. I wanted adjustability for the rollers to accommodate all shell diameters.
The main construction is plywood, some hardboard, and 1/2" PVC sheet stock for a smooth fence. The rollers are a variation of a Norm Abram's design he used for out feed rollers. It's a custom roller made from PVC pipe, threaded rod, washers, nuts, and some bearings. I like it because you could make it any size you want and not pay a fortune for large scale conveyor rollers.
Step 2: Installing Reinforcement Rings
Back in the day (I believe it was a Wednesday), reinforcement rings (re-rings) were placed in drums to add strength and aid in keeping the shell from distorting in shape ... AKA - staying in round. Modern day plywood shell production techniques have improved, so they aren't required, but they do still serve other purposes.
The addition of reinforcement rings focuses the sound of the shell ... it also raises the fundamental pitch of the shell, which isn't desirable for some builders. Another benefit is in regard to the bearing edges. This 8-ply shell is only around 1/4", which isn't much real estate for an edge profile. The re-ring increases the shell thickness at the edges, which creates more material to work with when cutting edges.
I make re-rings from shell cut offs and it works best when they are the same diameter as the drum with which you are working. In this instance, the re-rings come from a 3 1/4" depth of 13" 12-ply shell stock, so I was able to get two 1 1/2" rings out of it. Cutting the ring to size seems intimidating, but just sneak up on the cut and you'll be fine.
Fitting the Re-Rings
1. Make a cut to open the ring. I use a bandsaw, but a jigsaw or any hand saw would work.
2. Square/clean up one side of this ring. I use an oscillating belt sander, but a sanding block would work.
3. Clamp on end of the severed ring inside of the drum shell and then add clamps in various locations around the circumference. The goal is to keep the ring tight against the shell for accurate marking.
4. Make a mark at the point of overlap .. I usually mark a bit proud since I can always remove material as necessary.
5. Cut off the excess material.
6. Square up the newly cut site using the OSS.
7. Test the fit.
If you are amazing, it fit perfectly the first time.
If you are like me, make a few trips back and forth to the OSS and sneak up on the fit little by little.
If you cut it too short, don't panic ... maybe swear a bit. Once the ring is glued in place, you can come back with some wood filler or glue and sawdust magic.
To install the rings, just slather a nice even coat of wood glue and slide them into place. If your dry fit was perfectly snug, the glue is going to cause unexpected friction. I use a block of wood and light tapping until I get the ring flush with the edge of the shell. Once installed, take the time to wipe up any glue squeeze out. You don't want any of it soaking into the grain of the shell because it will make any and all finishes look blotchy.
For a nice, gap free bond, I add spring clamps around the entire circumference. You'll get more squeeze out, so be mindful and clean it up as you go.
Step 3: Laying Out for Hardware
To layout the hardware locations, I use commercially available layout mat. It has marks for drum diameters up to 28" and gives all the lines the placement of lugs (6, 8, 10, and 12 lug configurations), throw off/butt plate, kick drum spurs, and snare beds. You could do it all with seamstress tape, but I don't have that level of patience.
I marked directly on the drum since I'm using a pencil and will be sanding the shell before applying dye, but masking tape will keep your shell mark free.
1. Center the drum on the mat - the concentric rings help with this.
2. On the bottom edge, mark the locations of the lugs (8 in my case), throw off and butt plate.
3. Use a combination square to extend those vertical lines across the shell.
4. Use a combination square to mark the actual hole locations on these lines.
I'm using tube lugs, which have a post/hole spacing of 3 1/2". When centered in relation to the edges, that puts the hole locations at 1 1/2" and 5" in from one edge .. I usually reference off of the bottom edge.
Note: You could make your marks by measuring in from each edge 1 1/2", but if your shell edges aren't 100% parallel, you could end up with holes too close together or too far apart. It's not a deal breaker because you can just enlarge the holes a bit, but I'd rather not do that.
The throw off looked best with it's bottom inline with the bottom of the tube lugs. The butt plate looked best with it's mounting holes in line with the bottom tube lug holes.
Step 4: Drilling for Hardware
All of the necessary holes could be made with a handheld drill, but I do most of the work using the drill press. I mark/start all the hole locations with an awl, which helps guide the bit exactly where I want it. My bit of choice is a step/unibit. I tired brad point bits, but I found that they sometimes wandered. The unibit doesn't wander at all.
I take my time drilling the first lug hole to the required size, set the depth stop at that point, then drill the rest of the holes. Throw off and butt plate hole size will vary depending on the manufacturer.
One exception to the drill press rule is the butt plate. I start the holes on the drill press, but I finish them with a handheld drill. If you make these holes on the drill press, the screws will not properly thread into the butt plate because they will be angled inward.
You can see in the pictures that I made a shell drilling fixture for the drill press .. because of course I did. It's constructed from plywood and is essentially a cradle for holding a sacrificial 2x4, which supports the drum shell and eliminates internal tear out during drilling. It has a wooden disc/post on the bottom, which fits perfectly into the existing mounting location used for the cast iron table.
Step 5: Fabrication the Split Vent
I spent quite a bit of time thinking about zipper placement. Seriously ... it was agonizing.
Split Vent Layout
Since I knew that I wanted the open end to terminate with a large hole and I wanted that point to be one panel to the left of the throw off, I started by marking the center of that panel and drilling a 2" hole using a forstner bit.
Next was deciding on the point where the zipper would start to open. I wanted that transition to be visible to the audience, but there were other parameters to consider.
1. This would be the point were the two sides of the zipper separate and gradually widen until they reach the 2" hole. If I started it too far "in front" of the butt plate, I'd run into issues .. both visually, as well as with stability when mounting the plate to the shell.
2. I didn't want the pull in the same panel as the butt plate, nor did I want it to fall under a lug.
3. The zipper is 36" ... I didn't want to run out of teeth before reaching the 2" hole.
I decided to place the pull within the panel to the left of the butt plate and favored the right side a bit as insurance against running out of zipper track.
Third item was determining how the zipper should open up - one gradual incline, asymmetric, zig-zagging around, etc. I decided on the gradual approach, made reference marks at each lug location, and connected those points using a flexible, metal ruler.
The last decision was starting point for the bottom stop. I left this one for now to avoid a catastrophic mistake.
Split Vent Cut Out
To remove the bulk of the waste area in the "open zipper zone," I used the jigsaw. I stayed away from my line by at least 1/8" because I knew the blade would leave unclean edges and possibly some tear out.
For the finish cut, I used the trim router with a 1/4" straight bit and guide bushing. A temporary fence was created by using a long scrap of 1/2" thick PVC flat stock and quick clamps. The PVC easily bent to match the curvature of the drum while maintaining a square edge for the router bushing to ride against.
With the "open zipper zone" cut out, it was time for the "closed zipper zone. It turned out that a 3/8" straight bit was the perfect width for the zipper. I wanted the cut to be in the middle of the shell and do to that, I used the edge guide which came with the trim router. I cut out the slot to around where I wanted it and did a dry fit with the zipper to see how the length situation was doing .. it's was pretty good. I didn't want the bottom stop too close to the throw off and I didn't want to be directly under a lug, so I went slightly left of the lug within the same panel as the throw off.
Final shaping and contouring was done with a bastard file and sand paper.
Step 6: Attaching the Zipper
Installing the zipper was easier than I had anticipated. I mixed up small batches of two part epoxy and started at the closed end. I used enough for even coverage on the tape, but made sure not to overdo it because squeeze out would be a clean up nightmare. To hold the zipper in place as the epoxy cured, I used frog tape.
It turned out that I had plenty of zipper length left ... extra in fact. The excess was easily cut off with tin snips, ends glued in place, and then left overnight to cure.
Learn From My Mistakes: Install the lugs on the shell before gluing in the zipper ... that will take all of the flex out of the drum. I had 2 on the drum, but I should've attached them all. The zipper did distort a tiny bit with final assembly since I didn't take this precaution.
Step 7: Branding the Shell
Most custom builders attach badges to the drum exterior, but I don't use them because I want as much of the finished shell showing as possible. I use a toner transfer method, which I learned from John Heisz. Just print the desired text/image in reverse using a laser printer (ink jet won't work), tape it in place, and make a few passes with acetone on a rag .. a paper towel also works.
Step 8: Dying the Shell
I wanted this drum to be VERY black and for me, ebony stain just never gets dark enough. I've read about people using and being very happy with india ink, but I opted to use leather dye based on having seeing the results in person on other drums. I bought a 4oz bottle off Amazon and while I was worried it wouldn't be enough ... it's totally way more than enough. I'd say you could easily blacken a 4 piece kit with this small bottle.
I went with two thin coats figuring I'd have more control with that method. The coverage surpassed my expectations. I was hoping for a bit more wood grain visibility, but I wanted VERY black ... I got it.
Note: I taped off all of the hardware holes from the inside so that none of the leather dye would bleed to the inside. The light coats also helped minimize this risk.
Step 9: Bearing Edges
Bearing edges are cut using my big ass router table. I clamp a straight edge down to the table so that I have two points of contact on the drum shell. I find this gives me more control and the cut is more consistent compared to just running the shell around the bit freehand.
For this drum, I used an offset 45-degree bearing edge. It's also referred to as Standard 45-degree or just 45-degree. Some basic information on bearing edges can be found here. My bit of choice for this edge is a Diablo 45-degree chamfer bit.
I cut through 3-4 plies for the outside edge, and the remaining 16 plies for the inside edge. You can start with either edge, but I prefer to establish the outside edge and then make the inside counter cut. I'm cautious, so I take several smaller cuts .. raising the bit between each pass until I get my desired edge.
Step 10: Snare Beds
Snare beds are made on opposite sides of the bottom edge ... in line with the throw off and butt plate. Some basic information on snare beds can be found here.
There is a commercially available sled for cutting snare beds on a router table and a shop made version is on my to do list, but for now I shape them by hand.
I used a piece of tape on the shell to mark the width of the snare beds ... so I know my boundary side to side. I sanded down about 1/8" inch in the middle of the bed with a gradual incline/arc on each side. The bulk of the material was removed with the orbital sander, but final shaping and smoothing was done with a sanding sponge, as well as by hand with 150 grit paper.
Step 11: Oiling the Shell
Experience has taught me that I do not like doing lacquer finishes on drum for many reasons. First and foremost, I'm not very good at it. In addition to that, I don't have the equipment - spray guns, spray booth, patience to build the coats and sand them back over and over and over. Truth be told ... I don't really like high gloss finishes anyway. I prefer matte finishes.
For this drum, I went with two coats of boiled linseed oil. I used very light pressure because I was expecting the oil to pull out some of the black dye, which I really didn't want. To my surprise, aside from a small amount of color transfer to the cotton rag, there was no actual loss of color.
I oiled the exterior, as well as the interior, and let the shell dry/cure overnight. The next day I applied a coat of paste wax and then buffed it out.
Step 12: Fixed Zipper Pull Position
I would've been cool to leave the zipper tabs free to move, but that would result in a lot of rattling, which may be good on a tambourine ... but you don't want it on a drum.
To lock the tabs in place I used two part epoxy. I decided to have the internal tab lay flat, but have the exterior tab angled a bit for no other reason than I liked the way it looked. It almost makes you think the zipper is actually functional. I used tape to hold the tabs in place while the epoxy cured.
Step 13: Finishing the Zipper
First thought for getting a metallic finish on the zipper teeth was spray paint, but that would be messy. It would also require a lot of extra work ... mainly masking off an entire drum inside and out.
Second thought was to brush on model paint or acrylic paint, but I didn't have any.
Third and best idea was the pewter Rub-N-Buff I bought years ago for costuming and totally forgot about until now. It's a blend of carnauba waxes, fine metallic powders, and select pigments for a finish no paint can duplicate. I now that because I did I copy/paste from the official website. Added bonus ... the more you buff it, the more it shines. That in itself creates some really cool contrast.
I applied it with an old paint brush.
Step 14: Assembly
Assembly is pretty straight forward.
1. Lugs are attached using bolts and washers, which as through their respective holes from the inside of the shell.
2. Throw off and butt plate are attached using provided bolts and washers.
3. Drum heads are hoops are next. The hoop with the snare gates goes on the bottom ... and the gates are inline withe the snare beds.
4. Hoops are held in place with tension rods, which are just specialty bolts for drums. I add a dab of lithium grease in the lugs to keep the threading lubricated. I start the tension rods by hand, take up most of the slack with a drill, and then tension/tune by hand.
5. Snares are added last. They are connected to the throw off and butt plate via snare straps, which pass through the gates on the bottom hoop.
Step 15: Glamour Shots
Obviously I'm biased, but I think this drum looks pretty sweet. I'd like to do another variation with the zipper closed all the way around the shell ... more of an inlay effect.
How does it sound?
Pretty good. It's dry with a quick decay/short sustain. It packs a punch and it's loud. Again, Split vent and large vent snares exist ... they are a thing.
Can we hear it?
I plan on getting it into a studio this summer in order to get audio samples.
Can you make it so the zipper moves and the sound can be changed?
Yes and no.
No ... the zippers won't pull the plywood shut.
Yes ... I image you could add some kind of stretch fabric which would allow you to close the zipper, but then things are going to rattle and make noise. Something could probably be engineered to have sliding panels which closed the gap, but the hardware mounthing bolts and re-rings would be obstacles.
Shell: 6 1/2" x 13" Keller maple 8-pl
Re-Rings: 1 1/2 x 13 Keller 12-Ply cut offs
Lugs: Drum Factory Direct
Hoops: Drum Factory Direct
Throw Off & But Plate: DW 3- position Magswitch
Snares: Puresound brass 20 strand wires
Tension Rods: Drum Factory Direct
Top Drum Head: Evan coated reverse power center
Bottom Drum Head: Evans glass 300
Finish: Leather dye, boiled linseed oil, and paste wax
Zipper: Plastic 36" zipper from Amazon
Adhesives: Wood glue and epoxy