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 approach.



Process Menu:

Materials

Veneer Grades

Measurements

Cutting

The Sound Hole

Gluing and Clamping

Sanding

Finishing



Materials

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]

3) Pencil

4) Square

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

15) sandpaper

16) sanding machine

17) wood clamp

15) jig saw

16) powerdrill



Veneer Grades

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.



Measurements

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 mill.

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.



Cutting

Plywood is 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.

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The Sound Hole

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Gluing and Clamping

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 the glue.

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.

UNDER CONSTRUCTION

UNDER CONSTRUCTION



Sanding

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.

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Finishing

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.

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