Below I’ve documented how I’m thinking about the design for my upcoming cajon project. I have a few unresolved design / construction questions that I’ll put here. I’d love any thoughts people have 
- What wood species to use
- How to best attach the back
- Ideas for the veneered front
I’m also imagining I’ll want to use tools I’m not yet inducted on, so if anybody is interested in collaborating on this or even building your own at the same time, give me a shout.
The Cajon Project
I’ve decided to build a cajón. From Google: ‘A cajón is a box-shaped percussion instrument originally from Peru, played by slapping the front or rear faces with the hands, fingers, or sometimes implements such as brushes, mallets, or sticks’. Basically it’s a box that you sit on and sounds a bit like a drum kit with a bass note and a snare. I used to play the drums and think it’ll be fun to have one and it’s relatively small so won’t clutter the flat too much.
Three cajons: Left, Thomann TCA 414, £80; middle, Meinl Artisan Solea, £233; Right, Meinl Artisan Martinete, £1066
It’s a pretty basic instrument. You’ve got a box sitting on rubber feet. A back panel with a sound hole in it. A thin plywood skin on the front called the tapa that is screwed on (to allow access inside, replacement if it breaks and for the desired sound). Inside the tapa you have either some guitar strings or a drum snare to give a snare sound.
You can buy a basic cajon for less than it’s going to cost to build it, but you can also spend >£1000 on one. A basic cajon tends to be made of plywood with extremely basic joinery (butt joints and an internal frame). They’ll have a fixed, non-adjustable snare. They seem to be totally adequate!
Mid range gets you higher quality plywood, some snare adjustment, a slightly stronger construction e.g. rabbet joints and probably some aesthetic touches like a veneered front and perhaps some other embellishments.
At the top of the range you seem to get solid wood, often poplar for some reason I haven’t yet understood, extra fancy veneers and embellishments. The construction remains pretty simple, perhaps a locking miter cut with a router for the corners. The tapa is normally still ply even at the high end for sufficient strength at 3-4mm thick, but the veneers and inlays get more exotic and pretty.
What I want to build
- Solid wood cajon. Tbc on species. Any inputs here?
- Poplar is tempting as it’s used on many high end cajons and is cheap. Difficulty is finding nice looking boards, I think you’d want to pick them out not order online.
- Maple, Ash, Oak, Beech and various others are also talked about.
- A single board will be tricky as it needs to be about 30cm wide so I was thinking of getting a thick enough board to resaw and bookmatch which should also look nice.
- Adjustable snare. Haven’t decided whether to go for a drum snare or guitar strings yet.
- Overbuilt joinery! I’m doing this for the woodworking project more than the instrument so I’d like to go all out. My current thinking is:
- Mitered dovetails on the top of the case. I’ve seen examples of this being done and rounded over and it looks great! Lets hope I can be precise enough. I imagine rounding over all this changeable grain isn’t super straightforward. Would you use a router or sand the profile?
- Half lap dovetails on the bottom, the traditional approach to the bottom of casework. The tails are on the bottom, so from the side you can’t see the joinery. If I fluff up the dovetails on the top, I could always bail on the half-laps, flip it over and have another go for the top.
- Solid back joined somehow. I’m not sure how to do this yet. Initially I was thinking you’d bottom it out and glue it into a groove in the sides/top which would make it very strong and resistant to racking but it wouldn’t allow for wood movement. You could do this with ply, but I want a solid back. I’m now thinking you treat it like a frame and panel so recess it into a groove but with a small gap and either only glue one side, the middle or nothing at all. The challenge here would be to allow some wood movement but prevent any unwanted rattling. Any inputs here?
- A veneered front. I’ve crossed the first hurdle finding a supplier of very high quality 3mm ply. However, I’ve never veneered anything so I don’t know how far to take this. This could be a full on marquetry project or a case of slapping on a single nice veneer. I’d love any thoughts from anybody who’s done a bit of veneering.
I’m a bit rusty with my dovetailing, so I think my plan is to keep refining the plan and sourcing materials, and in the meantime practice the mitred dovetails that I’ve never done before. I’d love any input on the project, I know we have a few folks who are into their joinery as well as some instrument makers.
I think it sounds pretty decent but I don’t have a good reference point. I’d like to have a go on a commercial one and see. The snare for instance was just a guess of how to do it well and could probably be tweaked.