The BOWL CAJON or the Trials, Tribulations, Pitfalls and Triumphs of Inventing a Musical Instrument

This is the story of the ups and downs relating to turning the kernel of an idea, into a fully fledged musical instrument. It has been a path of numerous knock-backs and challenges, of great highs and some deep lows.

It's not a finished journey either, it's just that I have reached a point where I believe I have a viable product in which I have great faith and for which I have great affection. I also know full well that there are more developments I can make, to take things even further.

My little drum has opened whole new worlds for me. My first ever live playing with a band of musicians, in front of a live audience, was in my 60th year, brought about because someone heard me playing and liked it. I now find I can't get enough - the gigging pictures at the end of the story say a lot in themselves, there are around half a dozen different bands on there that I have played with over these last two years. That is one dimension in this journey I never expected or sought, but it has been a wonderful serendipitous outcome I couldn't have expected but absolutely love. Thank you for checking this out - I hope you find my story interesting.

Step 1: ​THE INITIAL IDEA

Back in 2010 I determined that I would build a Cajon. Most people will know that a Cajon is a box-type percussion instrument, upon which the player sits and bends over to strike the face of the cajon with the palms of the hands. The Cajon is capable of some lovely deep sounds, and is a flexible instrument in that it can be played to accompany many different music styles.

However, right from the start I wanted to build something different, with the main emphasis being on portability.

I began to do a lot of research - and discovered that in the ‘small cajon’ arena there were a number of options, from Bongo Cajons, to things which look more or less like a shoe-box, made of wood. These days there are tall Conga-Cajons, and all sorts of things. In 2010 I could not see the object of my desire either as a finished instrument, or as an instrument I could fiddle with to get what I wanted. I particularly was not keen on a simple box.

One evening I was watching a rather splendid acoustic guitarist on TV - I can’t remember who it was - but he was playing a really fast percussive style of play, with frequent raps to the face of the guitar with thumb and the points of his fingers.

Straight away I realised I was looking at the sort of instrument I was trying to get to. By striking the body of his guitar, he was making a drumming sound, and the flash of inspiration struck me immediately. I considered the notion of a guitar body, without the strings and neck etc. Obviously, I immediately realised the shape was not an issue, so the guitar shape was discarded.

I quickly formulated the idea for an all-wood drum, with air hole on the top (because that’s where it is on the front of a guitar,) and shaped like a bowl. Why a bowl? well, a nice curved bowl is along the lines of the belly of a guitar, it is smooth and therefore comfortable to hold, and doesn’t have sharp angles to dig into tender body parts.

Once that decision was made, I was on a roll, as I knew a number of people in the village where I live turn bowls and such for a hobby.

After some careful thought about sizing and such, I started to doodle some ideas. Picture 1a shows the general form of my idea, though without any dimensions.

Step 2: ​THE FIRST PROTOTYPE

I contacted a friend who I knew would be fascinated with the project,and asked him if he would be willing to turn a bowl for me. As it happened, I have done a lot of bits & pieces for him, such as mending and building computers, so he jumped at the chance to do something for me. By sheer fluke, he already had a perfect bowl just sitting there on his sideboard.

I had decided early on that I would have different sized sound chambers, like bongo cajons have, and so I made the doodling called picture 1b. I sent all the doodles to my friend, who immediately set to work (he was extremely keen to make the prototype, and I couldn’t really stop him!)

Picture 1c shows the temporary mock-up of the baffles within the bowl. They are held with Blutack, just for positioning. They were later glued into place.

The bowl is a lovely dark hardwood, though I can’t say which species. The ‘skin’ of the drum was always to be made from plywood. I sourced some lovely high grade 3mm birch ply, which my friend cut with a fretsaw, including the central air hole. The air hole has a simple design I made up from his first initial and mine, just to see how it would work.I calculated that if need be I could simply cut it out if I felt it was causing a problem. I decided to experiment with the air hole, right from the beginning, as it’s a customisation I would like to offer going forward with production drums.

Everything seemed to be going swimmingly - except for one small (huge) fly in the ointment which my friend brought to my attention. It was this revelation which guided the whole of the rest of the development. What became apparent is that although the bowl seemed perfect to me, it is in fact, not actually circular around the rim. If the rim could be taken to be a cross section of a planet, the north/south dimension is a whole centimetre bigger than the east/west dimension.

Now - a whole centimetre may not seem a big deal, but when trying to get to mass production, it’s a disaster. Not a disaster if every bowl has the same problem, as it can be catered for if they are all the same, but if bowls have variable sizes, by even as much as a millimetre, then it’s a massive problem. I will discuss this further.

Pictures 1d, 1e, 1f, and 2 show the first prototype in more detail. You can see the general form, and the size of the thing. It’s really beautiful, and plays very nicely. The deep sound is partly to do with the very dense hardwood of the bowl and also the depth of the bowl.

You may notice that there is also a decoration on the skin of the bowl. This is just a water slide decal, applied after the first coat of varnish, before the second coat.

Right from the beginning, I decided that decorating the skins of the bowls would add individuality, and custom versions which would make each customer’s drum unique.

However, slide decals are really not that great. It’s quite hard to remove enough of the clear background material to make the design appear to be painted, or laser etched. We will come back to this topic.

Step 3: ​CONCLUSIONS FORMED FROM THE FIRST PROTOTYPE

After a short while playing and getting to know my new instrument, I sat down and started to give the whole project some serious thoughts.

First off, I must confess that right from the beginning I approached this project with the notion that if possible, I would create not just an instrument to satisfy my interest and fascination, but a product which, given the right turn of the cards, might turn into a bit of a money maker.

The salient issues, however, are repeatability of dimensions, and simplicity of assembly.

These are CRUCIAL issues.

It’s OK to make yourself a lovely one-off instrument, or even make 3 or 4 of them, as long as people understand that they are seeing the creation of unique instruments each time. And are willing to pay the high price for one.

It all comes down to how to fit the wooden skin to the bowl.

In the early days I was cutting skins by hand, to fit the bowls I had obtained, and cut the air holes, as well, by hand. The main trouble with this approach is that it looks rough and imprecise, and even though it may by some be seen as ‘homely’ others view it as unprofessional, unfinished and crude.

Furthermore, the fact that each bowl had a different shape aperture, it would have been impossible to look at mass production.

One of the things which emerged while playing the bowl was that the sound was a different tone dependant on where on the skin the drum was struck. This was not only evident when striking the different segments, but also within each segment.

Taking these thoughts into account, and striving towards a repeatable ‘product’ I determined to make a second prototype, with one single air space.

Step 4: ​THE SECOND PROTOTYPE

I sourced a number of bowls from a variety of sources - it’s surprising how different a 12” bowl can be, in size, depending on where you buy it!

Pictures 3 and 4 show the second prototype.

As you will see, I was toying with the idea of calling my drum a Tazon (Spanish for bowl) rather than a bowl Cajon (cajon being Spanish for box) but I decided that it would be difficult enough to invent a new drum, without inventing a previously unknown name. People know what a Cajon is, so therefore a Bowl Cajon is merely a bowl variety of box. There’s a logic there somewhere!

The skin on the second prototype is hand cut - and can’t you tell how crude it is! Even with water slide decals, it can’t hide that it’s pretty rough.

However, the main thing is the sound - and it must be said, I was delighted by the result. The single volume of air did not alter the fact that depending on where on the surface you strike, and with what part of the hand, a different tone is achieved. The playing characteristics are covered later.

Around this time, I was lucky enough to be introduced to a past drummer from Fairport Convention - you may have heard of them. This guy was not only intrigued by the drum - he even played it on stage, in front of a packed audience, on an encore tune at the end of a concert. I can’t tell you how exciting that was!!

The only fly again, was the crudity of manufacture, and lack of repeatability.

I had approached the maker of this second bowl, to discuss ongoing orders, and he was just not the least bit interested. He made individual items for his own enjoyment, and occasionally sold a few, just to make space for more. Each bowl was a different shape and size. The thought of going into mass production to him was total anathema.

I cast around my local area, and even spoke to people who turn and sell bowls on Etsy, and Folksy, and similar sites, for example. Virtually every time I was rebuffed - people just were not interested in doing the same bowl over and over again.

So this was the next reset point in the project. I KNEW I was onto something - the drummer guy said so. But at this time I could not find a way forward.

I had discussed the issue of bowls with a lot of people, and they really just managed to make me even more depressed. People said that the notion of repeatable sizes, by hand, was going to be very hard to accomplish. It would be easy for lots of bowls to be ‘close’ but not necessarily smack on, to the millimetre. Also, it was then pointed out that unless I went for good, long-seasoned hardwoods, with blanks of this size costing £50 - £80, I was likely to have problems anyway, with warping and splitting.

I was really depressed by now.

Step 5: ​THE THIRD PROTOTYPE

So, there I am wandering through a well known Swedish furniture store, when I saw a lovely big wooden bowl. It was one of those lovely things made up of glued blocks of wood,and it was just obvious that they had to be machine turned, and therefore a repeatable size and shape. Being made from blocks means it’s unlikely to split, as well.

I bought one, and straight away got to the next hurdle: How to glue the skin to the bowl, as the bowl, while being big, has a relatively thin wall.

I got over this by first gluing blocks of balsa wood around the whole inside rim. I could then get glue onto the supporting balsa blocks, and onto the bowl, and so the skin had a chance of sticking well.

This drum is really lovely, it has a deeper tone that prototype 2, and although is slightly more difficult to play standing up, it has nice properties which make it a good proposition.

Picture 5 shows the drum.

I decided to approach the ‘well known Swedish company’ to ask where they sourced the bowls, and to ask if they didn’t mind if I approached there supplier for a project which was not going to compete with them.

They quite quickly came back to say that they themselves manufacture the bowl (as with most of their products, apparently,) and that it was reaching the end of it’s availability life and would soon be leaving the shelves, for ever.

I wondered if there were any ways round this, and they said absolutely not.

So, again, I was stymied.

Step 6: ​THE FORTH PROTOTYPE

I decided that I would try a radical vector away from my initial ideas, and see if accurately sized and repeatable dimension ‘bowls’ might be available, though from a different source altogether. I decided to try my luck with regular drum shells.

Reading a drumming magazine, I found adverts for drum shells, off the shelf, and unfinished.

Although this was going to be a departure from my bowl concept, I felt I needed to check out this approach, just to see if the pro’s outweighed the con’s enough to shed my original plans and go this way.

I bought a standard shell from a supplier, for about £25. Once again I hand cut skins, this time a solid disc for the bottom, and a disc with air hole for the top.

The gluing challenge was even harder with this shell, as the shell itself is only about 3mm thick.

Again I applied the balsa block method to the inside of both the top and the bottom inside the shell and glued the skins into the shell.

Pictures 6 and 7 show the ‘shell cajon.’ I never bothered to paint, or varnish the drum, as it was totally exploratory. I have to say, it worked really well - and is an absolutely excellent drum.

But it isn’t what I wanted, so, once again, I sat down and started to go through my options.

Step 7: ​THE FIFTH PROTOTYPE - AND INTO PRODUCTION!

By this time, a dear friend of mine had become as deeply engrossed in my project as I was. He has extensive experience in business, and is keen as anything for the project to succeed.

We were both doing masses of research, to find a wooden bowl, of repeatable and accurate dimensions, which would not warp or split with age. A seemingly difficult task, until my friend found a company willing to look at fabricating the bowls from plywood. The notion was that three 1” layers of plywood would be cut on a water cutter (why this and not a router, I cannot say - but I went along with ‘the experts’) to create 2 rings, and one solid disc. These would be stacked and glued to make 3” tall rough bowls. The bowls would then be put onto a CNC wood turning lathe, which would make the bowl the shape I wanted (I had to tinker with the profile a little, to accomplish the CNC step.)

This seems to be the answer to all our problems! It would mean a supply of bowls, made to close tolerances, and orderable in batches.

One of the key objectives in the bowl design was to simplify, and strengthen the attachment of the skin to the bowl. What I did was design a ‘ledge’ inlet into the inside of the rim of the bowl. Glue is put onto the ledge, and the skin sits down onto the ledge. This makes the surface of the skin level with the rim of the bowl, but furthermore, it makes the gluing easier, and with both the horizontal ledge and also the edge, glue can hold both horizontal and vertical surfaces of the drum skin.This makes for a very strong bond - skins do not come lose. It also makes a very strong structure, I am (way) over 300lbs, and yet I can stand on the skin of a drum and it won’t break either the skin or the bowl.

I grasped this CNC solution with both hands, and paid a big chunk of the folding to get a prototype one-off bowl made, to see how the process might work.

Picture 8a is the prototype bowl from this methodology, it is clear as day that the bowl is made from plywood, though with sanding and colouring the finish is acceptable - or at east, it has proven to be acceptable to my customers.

Picture 8b shows the bowl, sanded and varnished. One of the variations for sale on my website is for a ‘natural’ bowl, ie, totally unfinished. (By unfinished I just mean it’s all glued, and such, just not coloured and varnished.) Other than that, for more money, I sell the drums any colour you like.

Step 8: ​THE DEVELOPMENTS OF THE SKIN

You can just about make out in picture 8a, that there is some marking on that particular plywood drum skin. That is the result of further research I undertook while the bowl making was being finalised. I got in touch with a laser etch company in London, and discussed my needs. They were very helpful indeed, and even sent me some samples.

I had known, all along, that manually cutting the skins was never going to be an adequate approach. I was incapable of making a perfect job of the cutting. In any case, I also wanted decoration, so I concluded that laser etching and cutting was the way to go. For a while I considered setting up a CNC router, but I feel a laser cutter provides a lot more scope for delicate decoration.

I organised a few test pieces, etched with my name, and the name of the drum, and cut, including the air hole, from 3mm ply. I have to say, with minimal final sanding these skins are excellent.

I mentioned before that I was always thinking of individual designs for the skins. Currently I can offer decal designs for free, but laser designs are really quite an expensive extra.

The thing is, my skins currently cost me £25 each, if I order one at a time. However, if I order 20 or more, of the same design, they come down to £5 each, which is splendid.

Of course, if a customer says he wants an etched dragon, or a Celtic design, or Viking symbol, I can design it and send the artwork off to the cutter, but at and extra £30 - £40 on top of the price of the bowl, I have had no takers. I would sincerely love to be able to make decorative air holes, and decorative drum skins, but at the moment, it’s out of my reach.

Obviously, by being computer drawn, and laser cut, the skins are the same size every single time. This was why the bowls also needed to be repeatable dimensionally, because it’s the only way the project makes sense. If the components are the same size every time it makes assembly and finishing a quick (therefore inexpensive) prospect. If the bowls are different every time, then the skins have to be individually cut to size. This takes time, and is sloppy and imprecise.

Step 9: ​THE FIRST PRODUCTION RUN

I have to say I had to take a big breath when it came to committing to buy bowls from the supplier we had identified. He had produced one good prototype bowl, at a very high price, and now we had the quote for a first batch of bowls.

The minimum order run he would contemplate was £1,000 worth of bowls. Sounds like a lot of money, and for me, it’s a HECK of a lot of money, and when you think this only constituted 20 bowls, well you can see why I had to sit and mull over this step very carefully.

Yet - having come so far, and believing this was the only way forward - I convinced myself to go for it, and make the batch order. Of course, I also had to make the batch order of skins as well, to make use of the volume discount. This would mean that any changes to the design on the skin would have to be at the one-off rate.

The first production run went well, and I finally had my hands on all the components of my drums.

Step 10: ​TURN IT UP!!

The first few drums I sold were entirely acoustic - but it struck me fairly early early on, from playing gigs with my chums in the Banbury Didgeridoo Club, that volume was an issue. The drum was brilliant in small venues, like small pub bars, and intimate little clubs, and for practicing at home. However, when we played in concert, I needed amplification, so bought a clip-on microphone which sat in the air hole. This was quite adequate for a number of concerts and gigs, but after a while I decided to experiment.

Pictures 9 and 10 shows a drum ( a red one this time, with a firebird decal ) with an XLR socket. The majority of the drums I have made and sold have been equipped with piezo electric pickups glued to the drum skin, and a socket for plugging the drum directly into a PA or gigging amp.

I can assure you, even in the loudest pub, my bowl is heard by the crowd.I have had very many positive comments from the audience after a gig.

Step 11: ​THE NEXT GENERATION

After successfully selling a few drums, I was faced with the situation of having to face purchasing another £1,000 of plywood drums.

It wouldn’t have been such a big gulp this time, as obviously I had already enjoyed the income from the first batch. However, a number of grumbles had started to work their way round my head, which made me launch again into a further round of reflection and research.

I had had a bad experience with the suppliers of the bowls, and decided that if there was any way I would try not to use them again. However, finding an alternative supplier was difficult in the extreme. Furthermore, once I had stored some of the bowls for a few months, I started to have problems with drilling some of them for the pickup plug, and for the clips which hold the strap in place.

I found on a couple of occasions that the bowl split along one of the laminations. It wouldn’t split where we had joined the 3 layers of ply, they would split within one of the layers. This to me indicated that I had been supplied with bowls made from ‘not the best’ plywood.

I still have drums from the very beginning of the run, and I am confident that with normal use, they are sound and will not crack under normal circumstances.

But - when one’s confidence is sapped, and one is looking to have to spend £1,000 with a bozo one has no respect for - it makes one stop and think things through - again!

And so - I started to look into vacuum forming (no one interested, and those who speculatively responded gave bonkers prices) I looked at other materials, and finally settled on trying to get to a workable solution with fibreglass.

Well, just recently I received my first fibreglass bowl, and made the very first fibreglass drum, just last week. Picture 11 shows the finished drum. 11a and 11b show the bowl and picture 12 shows the finished drum with a Jack socket which is linked to a piezo pickup inside the drum.

And how does it sound?? Its EXACTLY like the wooden version. A wooden bowl was used by the masters of fibreglass at Bedford Fibreglass LLP to make a buck (no mean feat when you think they had to smooth and flatten all those plywood ridges!!) From the buck they made a 2-piece mould and from that mould they have made my first bowl. I am incredibly happy, because once again it streamlines the process, as they provide the coloration via the gel coat, so I don’t have to sand, paint (2 coats) and varnish (2 coats) the bowl. When I get the bowl, it’s completely finished and ready to be made into a drum. I drill for the jack, and for the clips which hole the drum strap. Then, after varnishing it, I glue the skin into the ridge around the inside top of the bowl, and that— as they all say, is that.

The wonderful ongoing benefits of the fibreglass solution are: there are very many colour options, which I can offer to my customers, the bowls are made individually - with no minimum order level, and with (usually) only one week lead time, they are cost effective (work out about the same as the wooden ones, but by ordering one at a time it’s no sweat,) they are extremely robust, they are easy to assemble. All in all, it’s a wonderful solution, and one I am extremely confident to sell.

Step 12: ​CONCLUSION

Well, that about wraps up my story. It has been one hell of a roller coaster ride. I have spent a lot of money (don’t tell my wife!) and also shed blood, sweat and tears, trying to bring a product to fruition. I have tried numerous solutions - some rat holes, some simply impractical and some perfect in all ways, but not what I wanted. I now feel I have a product to be proud of. It is a unique product (OK, a lot like many other drums from various ethnic sources,) which in my view has a number of unique features. I love playing my drum, and all my customers say the same thing.

I am so happy with the fibreglass bowls, and now need to look further into establishing a custom level of skin decoration, I think it’s an important piece of the offering.

Above are a whole heap of gigging pictures, mostly from open mic night in pubs around where I live.

Picture 22 was taken last summer, when we were busking outside the Vintage & Modern Guitar shop in Thame.

Movie Sequence 5 shows 3 Bowl Cajons being played, without any amplification, together with a djembe, with my chums at Banbury Didgeridoo Club.

If you ever get to Thame, in Oxfordshire, try to get to the James Figg pub, for The First Thursday Music Club (every month - yep, on the first Thursday,) and look me up. You can’t miss me, I assure you.

Thank you for coming along with me on my story of this adventure, and if you feel my creation is worthy, then a simple message of support would be appreciated. If you think I am full of wind, you can tell me that as well. Take Care, T.

PS It may look in the photos that I am a grumpy old git - it may come as a surprise, but in most of the gigs I am actually grinning, it's just that twelve years ago I suffered from Bell's palsy, and it has somewhat messed about with my smile-muscles. I am actually having a whale of a time.

Step 13: VIDEOS

Four sequences of how the drum sounds with various taps and slaps. One video of 3 drums in action with my chums at Banbury Didgeridoo Club - no amplification.