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Building a Goblet Drum

Yes! You too can make your own drum! See below for details on how it's done

! Do it today !

In the Spring of 1994 I made this hour-glass shaped drum as part of an experiment in 'Urban Materials Utilization'. There was a need to be outfitted with a drum of some kind so that I could attend a 'Shamanic Workshop' held in Carbondale, Co. in the Summer. I wanted to build the drum myself so that my spirit would be part of the drum. I also thought that it would be interesting to design a drum that was made out of materials that I had around the house. In doing so, I somehow created what one might call a 'plywood' drum made out of broad sections of wood composite (the kind used in floor underlayment). Basically, I cut rings out of this material with a band saw and glued them together. The hour-glass shape of the drum body was an important factor, because I used the 'donut hole' from each inside ring cut to make a smaller ring, thus reducing the amount of waste material. An enlarged view of the drum with the heads removed will give you a better idea:

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You can see the layers of wood inside the drum. The outside of the drum is smooth; it is coated with several layers of sealer and painted. You cannot see any of the wood plies on the outside of this drum. But, this is old data... This drum was wear tested-- I beat the hell out of this drum for a year and it didn't break.... but I saw the need to continue. I was driven to build a BIGGER, LOUDER drum!

This Here Experiment

OK, so I plan to build another drum. What I plan to do here is update this list every week to show how far I got with the drum during it's construction. I will be taking pictures of the work in progress. I will be using a digital camera to capture most of the action (Yup, I don't have to go to the drugstore to have the pictures developed!). And I will report any new ideas and design changes AS THEY HAPPEN! (Well, as soon as I can, anyway). So, THERE!

Computer Generated Goblet

The design of this drum was based on what I learned from the hour-glass design. I needed to make the body tapered enough to reduce waste yet big enough to produce some loud bass sounds. I also had problems keeping the heads tuned on the old drum, so I figured a way to mechanically tune the head. I used some freeware CAD software to produce these 3-D drawings of the drum body (what I will call the Goblet Drum from now on):

GOBLET DRUM BODY DESIGN

Here is what I would like the drum body to look like. The drum diameters and height are approximate values.

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GOBLET DRUM DETAILED

Those extra rings on the goblet stem are for tuning the instrument. I plan to run the drawstrings through holes in the first flange and tie them onto machined eye hooks from the bottom flange. The drawing on the right shows the design concept with a drum head attached.

GOBLET DRUM PLY

Here is an exploded 3-D view of the goblet rings. Yes, I plan to cut 18 inch diameter rings out of wood composite and glue them all together! I like this drawing. It reminds me of Dali for some reason.

The Circles of WOOD...

The first drum (Hour-Glass) was a test (I can say that now) of how certain materials could be combined to produce a desired effect. The drum body was strong enough to endure the usual banging around that a normal drum would receive. The sound quality was 'OK', as it had its moments from day to day, but I am attributing that to the way the head was fixed. I also think that I could improve on the tuning of the old drum by rigging the lacings so that they could be more easily adjusted. SO, I will start off building the bigger drum the same way. I did not have any more 'wood' so I made a trip to the local Home Improvement store and purchased a 4'X8' 3/4-inch piece of floor underlayment. (It's the stuff that looks like a composite of all sorts of wood chips and glue). The wood was cut into smaller sections and then circles were cut out with a ban saw.

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In the first picture you can see one of the smaller sections sitting on the band saw. The second picture shows most of the bowl of the goblet completed. Each section is marked showing the degree of cut and overlay point (as each circle is cut, it is used to mark the size and shape of the next section to be cut).

Gluing the drum sections

The sections were glued using Elmer's Woodworking Glue (aliphatic resin) and clamped overnight with a pipe clamp. The first picture unclearly shows the body bowl between two sections of wood. The pipe clamp runs through the middle of the body, so you can't see it. The second picture is an illustration of an additional gluing step performed before the sections are put together. Instead of messing with broken saw blades, I simply cut a diagonal through each section in order to cut the inside hole. The kerf (the wood that is removed from the cutting action) was small enough as to not have any noticeable effect on the circular section. I glued each circle together and held them together with tape overnight.

Shaping the Drum Body

After all the rings are glued together and set aside to dry for a few days, the drum body should be smoothed down. The rings overlap, sometimes as much as 0.25" in a few places because I cut each ring without a circle cutting jig (That would have been nice!). Sometimes I lost my train of thought and veered away from the circle.-- Well, that's what happens when you cut things by hand. Anyway, the end result is that the body looks like the U.S. Embassy building in Dublin (Ugly or what?) and has to be shaped down into something a little more organic

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looking. I used a hand shaping tool to make the rough cuts and then I finished off the surface with sand paper. It is not worth sanding the particle board too much because with all those mixed-up grains and glue, you can't really get the surface too smooth. I just get as much of the larger gaps left from the shaping tool as I can. The photo below shows a composite view of the sanded drum bowl on the left half and with a first coat of white sealer on the right half.

I am using some gesso that was left over from another project as sealer material. I have been sanding between each coat-- It may get as many as 8 coats of gesso before it's done.

DESIGN IDEAS HERE

If you haven't figured it out by now, I am designing this drum while I am building it. (Damn it Jim, I'm a scientist, not an engineer!) I have been giving thought to the drum head-- just how am I going to make it work? My experiences with drum heads in the past (and some physics courses I may have taken) have led me to believe that the secret of making a good, sound drum is this: "It's all in the rim." A lot of this concept was evident when I built banjos. It didn't seem to matter what material was used for the shell as long as the rim was made of a hard material that was rounded off where the drum head made contact. A steel rod is shaped to fit the outside edge of the banjo shell. The drum head is stretched over the rod-- it doesn't touch the shell. This rod is known as a 'tone ring'. So, when I was in the hardware store the other day, I saw some coils of copper tubing. Copper is a wonderful metal. I love copper. I think this drum will have a tone ring made of copper! See the drawing:

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The drawing shows a cross-section of the drum. The thickness of the wood is finally revealed. Note that it is thinner near the head. I have also shown a detail of the tone ring. I may make the tone ring next week. Stay tuned!

Finishing body parts ! We're Almost Done,

Folks!

Hello again. I unfortunately have been concentrating too much on the goblet bowl last week to get back to the balance of this project. I would sand it a little, and then give it another coat of gesso, and then stand back and take a long look at that sucker. This is one LARGE drum! One of my biggest fears was that the rim of the bowl might separate while I was working out the kinks with the hand shaper. As it is only a half inch thick at the rim, there is less wood to make contact with the next piece down, so the top of the rim is weaker than the rest of the bowl. Also, the weight of the drum could cause it to implode on itself at the rim if I wasn't careful about how I positioned the drum body on the work surface while I scraped off the excess wood. It was important to use care when handling the bowl and not use too much force with the tools when I was scraping near the top of the rim.

I finished up the flanges on the stem of the goblet and cut some more circles of wood for the foot. The foot was cut so that the center hole is the same diameter from top to bottom, while the outside diameter was increased to give it the 'fan-out' profile of a goblet. Here is a picture of the foot all clamped together:

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I'm just 'showing off' how many C-clamps I own! I have lots of clamps because I get a thrill out of gluing pieces of wood together. This next picture shows the three sections of the drum; the bowl, stem., and foot.

I have decided to make the flange section out of the same material as the rest of the drum. I do have some concerns about how well the bottom flange will hold up under the tension of a stretched drum head. I may decide to set in some metal reinforcing plates behind the flange to help spread out the force that each eye-bolt will have on the wood. If I find some suitable material in the next week or so, then I will probably do that. Here is a preview of the final 'look' of the drum:

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The three sections have not been glued together yet. I think that I may use some dowel joints, especially for the foot section when I finally glue them together. The height of the drum is a little more than in the proposed design. It is now about 27 inches high. You probably wonder how much this drum weighs. Well, so far it comes to 20 lbs. With the addition of a toe piece and the drum hardware, the final weight could be around 23 lbs.

Head Fitting (Attaching the head)

This page describes the technique I use to 'fit' a head to a drum. It is a method to help produce a drum head that conforms to the rim of the drum. I am using a copper 'tone ring' and a steel 'tension ring' for hardware as mentioned in a previous page. I don't always use this hardware, but this is an experimental drum, after all. The head material I will be using is goatskin. I suppose that since the drum body is made out of floor underlayment, I should be using some sort of scrap plastic sheeting material for the drum head, you know, the 'urban materials utilization' thing I mentioned earlier. I would have, except I haven't been able to make a good looking plastic head (well, maybe I haven't really tried-- I don't work in plastics very often). I use plastic heads for banjos (Remo makes them, of course) and they are better than natural skin because they do not absorb moisture. But natural skin is fun to work with, and fellow hand drummers tend to scorn plastic heads whenever they can. It's peer pressure! I've got goat-- I'll use it!

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This Drum Can't Be Beat (yet)

Me, with drum and Peruvian hat.

The Tone Ring

The tone ring was made from a half inch diameter copper tube that was bent into a hoop. The hoop diameter was just a bit larger than the outside diameter of the drum bowl. A smaller piece of copper (about 1 inch length) was split and fashioned to fit snugly inside of the tube where the ends of the hoop met. This intersection was generously fluxed and sweat soldered together (I'm using non-leaded solder in this picture). Just before soldering, however, I placed a little Mojo inside the tube. I can not tell you what it was, but it was something that I had in

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my possession for many years. It is now sealed inside the tone ring. If you were to shake the ring, you would hear it rattle inside the tube!-- This adds a personal touch to the instrument; It most likely will drive insane any of the spirits unacquainted with the presence of the mojo. Heh, heh!

After the tone ring has cooled down, it is centered onto the drum bowl. Some corrugated cardboard is taped around the edge of the bowl to act as a spacer between the body and the drum head when the skin gets fitted over the tone ring.

THE SKIN of the DRUM

Last year I went to a convention in Portland, Oregon. While I was in town, I purchased a nice piece of goat skin from a place called African Rhythm Traders. It was 26 inches in diameter. I was told that it was for a djembe (I guess there must be djembe builders in Portland someplace). I bet it will work on this goblet drum just fine! Anyhow, in order to prepare the skin for fitting, I first soaked the skin in tap water. I wait for the skin to get soft, like a wet noodle. In the case of this particular goat, the skin was under water for about an hour. (I've got some thick cow hide that may take three hours to properly soak, so the soaking time depends on the animal and thickness of skin, I imagine).

The skin is taken from it's bath and blotted to remove any excess water (so it's not dripping wet) and draped over the tone ring and drum bowl.

A steel tension ring is placed over the skin. I pushed the ring down to 2 inches below the top of the tone ring. It is a good idea to measure the distance of the tension ring around the diameter of the drum to make sure that the ring sits evenly on the drum.

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Interesting note: While I was in Portland, I stopped in at a craft store where I purchased some additional skins for future drum projects. (This is how I operate-- I go to conventions and buy skins!) While I was in the shop, I noticed that they had these steel rings for sale, about $3.00 for the 18 inch diameter size. I asked the store owner what they were for-- he said that they were for making dream catchers. I said that they would be good for making drums too, so I bought a bunch of 'em, in all kinds of sizes.

The outside ends of the skin that's left flapping under the tension ring is turned up onto the top of the drum head and held momentarily with masking tape. Make sure that the masking tape is not too sticky-- it should have just enough hold to keep the skin up until the next step:

Fitting the Drum Head

With the tape holding the skin flaps up, take some string and start winding it around the top of the tension ring. Start out loosely at first-- when you have enough hold on the skin flap with the string, then you can slip the masking tape out from under the string. Now you can wind the string around the skin tightly (I happened to use blue yarn for string, and it worked out O.K.) Keep winding the string. Go up to the bottom of the copper tone ring as you wind. While you wind the string, look for weird looking folds in the skin-- The skin is still quite flexible and you can pull on the ends of the skin to remove most of the big folds in the skin. Little folds won't hurt the drum, but there should not be any folds or creases anywhere on the tone ring!

Keep the string on the head, and let the skin dry overnight.

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By the next day, take the string off and pry off the head with the tone ring intact. The result is a fitted drum head! I have found that it is now easier to work with the head after it has been fitted and dried. I can now take my time measuring where I want to put the lacing and make the holes. When I put it back on, I will moisten the skin and trim off the excess skin-- but that's for next week!

This is the End.

Finishing up the Head

There are various ways to do this, but I usually do not have the patience to make some kind of fancy device for connecting the rope tension lines to the head other than making holes in the skin to thread the rope through. I have a banjo that I made with a lamb skin head that used an elegant brass double compression ring system, but that WAS a banjo, and this is a hand drum so ...

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Holes are made in the skin using a leather punch. The holes are just above the tension ring so that when the rope is pulled taught, the loop along the outside edge of the head will pull down on the ring and not rip a larger hole in the skin. For this drum, I punched out sixteen (16) evenly spaced holes. I purchased about 70 feet of medium weight nylon rope for the lacing. The fitted head was moistened with a little water to soften it up a bit and the lacing rope are looped through the holes. For this drum, 16 lengths of rope (about 4 feet each) were looped through each pair of holes. After all of the rope was looped through, the head was placed onto the drum. This whole process was done rather quickly so the drum head did not get a chance to dry out. (It is best to keep it moistened enough to stretch the head over the tone ring properly). The ends of the rope were tied onto the eye bolts down by the flange. This process proved rather messy as the knots sort of got out of hand at times (I only know how to tie three kinds of knots). I promised myself that I would work on the knots latter-- in the meantime, while they continued to hold I took out an open ended wrench and began to tighten the bolts on the end of the flange. Just a bit at first, going around the flange and tweaking each eye-bolt a little. As tension increased on the rope, I could judge just how even the rope tension was by the sound of the note as I plucked an individual rope like a bass fiddle (there was an 'open' string area between the top flange and the side of the drum that made this possible. This was one of those lucky undocumented features that you sometimes get ;^/). This whole process went by rather quickly... I didn't stop to take pictures (sorry), but there is something about tuning an instrument, especially one that you have made by yourself. Anyway, before I did any drum head work at all, look what I did:

I had a white drum and I had it painted Black

One night, I had this dream about a black drum... so I spray painted the drum body with flat black paint. It has a kind of industrial look to it now. I think that flange especially looks good in black! Hey! I can do anything I want! It's my drum!! So... All tightened up and ready to go, with all the pomp that goes with the WWW, I am pleased to introduce the following shameless gimmick:

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