How To Build A Cajón
Upon deciding you really want to build a cajon,
remember to use plywood because solid wood is EXTREMELY expensive. I
have seen cajons built using many types of wood but the most common is
birch of approximately 3/4" thickness.
The thickness is not set in stone however, and if you wish you can use
sheets as thin as 1/2 inch for descent results. If you go over 3/4 inch
on the walls it will only make the drum much heavier without improving the resonance.
** Remember, to build a cajón requires the patience to treat each step
with care. It would be a real bummer to go out grap any piece of wood
and try to slam it together in one day. Its best to try a slow steady
The Sound Hole
Gluing and Clamping
1) Table saw (or radial saw or skill saw)
2) Lumber (I purchase 4x8 peice of wood, 1 3/4" thick and 1 1/8" thick)
[If using table saw - Rip fence for rabbet joints]
5) Tape measure
6) Gorilla glue
7) Pipe clamps (5 or 6)8) Safety glasses
9) Ear protection
10) Stain or paint whichever prefered
11) water source
12) mallet (soft head)
13) small pieces of scrap wood with smooth sides
14) wood files
16) sanding machine
17) wood clamp
15) jig saw
When selecting the type of wood you want always remember to check the
veneer grade, most sheets of plywood will have it printed on the side
near the corners. Here is how the different categories break down:
A = Up to 18 neat repairs permitted, parallel with the grain.
B = cross grain knots and repairs up to 1 inch in diameter, as well as minor splits permitted.
C = Up to 1.5 inch knots permitted, splits and sanding defects that don't impair strength allowed.
C-Plugged = basically a higher quality C level veneer, splits can be
1/8 inch and other defects are limited to 1/4 X 1/2 inch.
D = Can include knots and knotholes 2.5 inches wide. splits and stiches allowed.
In my opinion the limit for your cajon
will be grade C because in truth you only need one surface of your
plywood to look good. Sometimes with grade C you will find it is hard
to get a clean surface from the whole sheet, but if you want the lower
price go for it.
The A and B grade sheets are really ideal because as the definitions
above suggests, they are ALOT easier to work with. But you can also
easily spend $80 for a good grade A sheet so keep that in mind.
Before measuring out pieces make sure you can correctly draw out the entire box with all six sides such that they will match.
Below is an example plan for an ideal sized cajón:
I use a rabbet joint on all my pieces which must be accounted for in the measurements to achieve the 16" x 14" cajón.
An important thing to keep in mind when buying plywood sheets is that
if you buy 3/4" plywood for example, the actual sheet will probably be
about 5/8" because the wood always shrinks after being cut at the saw
The example I used above involved an ideal plywood sheet, which you
will probably never find. So for the side panels where the measurement
is 16" x 13 5/8" it will probably be more like 16" x 13 6/8" because
after making a 3/8" cut on the front piece, there might only be about
2/8" remaining. So 14" minus 2/8" would be 13 6/8". The point of this
is that each piece of wood you use will be different, so you may need
to adjust slightly to get the perfect fit.
generally sold in 4x8' sheets so once you've purchased your wood and
got it to where you will be working, you may need someone to help you
with the first few cuts to get workable sized boards. You can also
sometimes get the store to cut a 4x8' in half to make it a little more manageable. The image above is me cutting a 4x4' board into 4x2' sections.
Remember that you need to follow you're measurement plan to allow the
greatest use of your wood supply. You should be able to get about 3
drums out of a 4x8' sheet.
My favorite glue is Gorilla glue. It claims to be the strongest for the
purpose of wood gluing. You can also use Elmer's wood glue however
which is very similar to Gorilla glue.
I usually take a piece of sand paper and go over the surface of the
rabbet joint where the boards will be glued. This provides a clean,
even surface for the boards to seal together well.
Then I'll take a moist rag and dampen the surface of one of the rabbet
joints, and apply the glue to the other board. This way you have one
board with a damp joint surface, while the other has the surface with
Make sure you use other sides of the box to provide support for the gluing
sides. For example if you are gluing the joint between the two sides
and the front peice, use the top and bottom also which will allow you
to clamp the boards inplace and insure a square frame.
Once you have all the pieces glued, there will likely be a few areas
where the glue seeped out of the joints during the expansion phase of
drying. I'll sometimes take a box cutter to cut off the excess
collections of dried glue (careful though, you don't want to make scratch the wood surface!)
I usually start with a coarse (40-60 grain) or medium (80-120 grain)
sandpaper and go with finer papers as I progress. I usually start with
an orbital sander. Orbital sanders can produce a nice even surface and
are really easy to use. There are 12 edges to round out so it can take
a while depending on how rounded you want the edges to be.
Another method you could try is using a wood file or wood rasp. These
are usually made of steel and are essentially like sandpaper in that
they smoothen out wood. Just remember that with wood files it is
especially important to file in the direction of the wood grain.
Once you've got all the pieces in place with a smooth surface and
rounded edges you need to decide what type of look you want. This is
entirely up to you really. A good brand I use for staining and sealing
is Minwax's Fast-drying Polyurethane.
You could go for the natural satin look or use semi-gloss or gloss
finish. The most popular colors seem to be glossy black, natural clear
finish, or other dark colors such as dark shades of red or burnt orange.
It's usually best to apply 2 to 3 coats of stain and then at least 2
coats of varnish to achieve a lasting finish. After applying each coat
it's important to sand over the entire cajón surface using sandpaper
with a grain rating around 220-240 (very fine). Wait until the coat is
dry first and then lightly go over the surface using the fine sandpaper.
After coating the wood with stain some of the wood grain may rise
causing a slightly uneven surface. In addition sanding the previous
coat provides tiny grooves which increase the adhesive abilities of the
next coating. The last coating is the only one you don't want to sand.