Roll Your Own Bongo Cajon

In this Instructable I will show you how to make a wooden bongo drum Ricky Ricardo (or a hippie, perhaps) would be proud to own.  All you need is some plywood and basic tools.  If you can operate a garage door opener you should be able to do this.  Gird up your loins and let's rock!

(Statement concerning garage door opener not tested for accuracy.)

Step 1: What We Need

Here is a list of the tools that I am using.  Your list may vary.  There are often many ways to complete a woodworking project (and let's not even get into excoriating felines).  This is simply how I did it and what I used.  As well, I am using cabinet grade Baltic Birch plywood.  You may use something else if you wish, though I cannot speak to acoustical properties of anything other than this.  Cabinet grade is important for a nice finish and to avoid gaps that would need to be filled.

Tools:
Table saw
Miter saw
Orbital sander
Sandpaper
Contour sanding grips
Protractor
Clamps
Wood glue
Toothbrush
Dust mask
Safety glasses
Anything else I forgot

Materials:
3/8" Baltic Birch plywood
1/8" Baltic Birch plywood

Yes, I consider glue a tool.  Deal with it.

Step 2: Long Sides

Start by ripping your plywood into 7" wide strips at least 16" long and some change. Line them up side by side with what will be the outsides of your bongo facing out and the insides in. Set your miter saw to 8° and cut one end off of your two boards.  Hold them together and cut them at once to ensure they are exactly the same size.  I like to clamp them together to ensure uniformity (see picture). Measure 16" from the long end on what will be the top of the drum and cut the opposite end to mirror your first cut. You now have isosceles trapezoids that will be the two long sides of your bongo.  (Who knew geometry was actually useful?!?)

Step 3: Short Sides

In order to have the top of the bongo lay perfectly flat across the top edges of all four boards we need to bevel the edges of the two short sides. We will use a table saw to do this.  As well, since the short sides are at a slight angle they will need to be slightly wider than the long sides.  You can do this with your miter saw as well, but I prefer the table saw.

Place your protractor against your miter saw blade to find the exact angle (yes, I know the saw says 8°, trust me, it's wrong) and lock the wheel. If you don't have a protractor like this you can use whatever angle gauge you have as long as it is accurate and it locks. If the boards you cut in step 1 were square with 90° ends you can even use one of the pieces you cut off to set your table saw. I do not (as I alluded to above) recommend simply trusting the numbers that are printed on your saws as they are of questionable and dubious accuracy.

Once you have your protractor locked into place you can line up your table saw blade to match your miter angle just like I am doing in the picture. The protractor is on the opposite side of the fence.  Lock the blade into the correct angle and measure the length of the mitered end of the long sides.  Mine came out to be 7 1/8" but yours may be different.  After cutting a bevel in a length of wood, measure the outside edge of the long side piece end and cut the end pieces to that length to form two parallelograms.  This is not the easiest thing to describe, so check out the pics to see what I'm talking about.  Frankly you are most likely not reading this anyway, so I'm not terribly concerned if my description is a tad convoluted.

A word of warning:  This is a crosscut and is subject to frayed and otherwise rough edges.  Use a blade that has a lot of teeth (at least 80 - see my blade in one of the pictures) and preferably one that is made for plywood.  Also go slow with this cut.  By heeding my warning you may avoid the rough edges that plagued my first attempt (see picture).  (I bet you actually read this part.  It has bold font and the word "warning" in it.)

Step 4: Gettin' Sticky With It

This bongo will be put together with glue.  It does not need nails or screws or any other fasteners to stay together as the stresses on it will be minimal and glue is very strong.  If you use a glue like Titebond, the wood will most likely break before the glue will.  So let's get started!

Make sure you have everything you will need ready and within reach before you start gluing.  There is nothing fun about gluing something wrong and having to redo it.  You will need wood glue, clamps, something to spread the glue around with, a wet rag and something like cardboard to catch any drips.  If you like to clean glue off of your work bench (or table saw, in my case) then please feel free to omit the cardboard.  As well, one can use her fingers to spread glue, but I like to use an old toothbrush.  Cardboard and toothbrush are optional.  Everything else is necessary.  Yes, you need clamps.  They are cheap at Harbor Freight.  Just buy some.

Before I go live I like to do a dry run and clamp it all together without glue to make sure it all fits correctly (I don't actually do this, but it sounds professional, am I right?).  If everything lines up well enough you are ready to rock.  Small issues can be worked into place and/or sanded.  Big issues should be corrected before you continue.  If you need to recut some pieces, now is the time.  Sometimes you can simply cut a bit off your existing pieces and make your drum just a hair smaller.  It won't make a huge difference and can save you some waste.  

If you are using bar clamps or pipe clamps it is a good idea to slide them close to the size you will need them so that you don't have to do much adjusting while your glue is drying.  We want to be quick and painless.  A little masking tape can keep glue off your clamps as well, but now we're getting really crazy.

When you are ready, spread your glue on either side of the end pieces.  Use your toothbrush, finger, or whatever appendage you prefer, to spread the glue evenly across all of the surfaces that will be touching others and then clamp those bad boys together.  You can keep the clamps somewhat loose until you get everything in proper alignment.  Once you are golden, tighten them up, wipe off any excess glue that has spilled out and go play with something else for the rest of the day.

Step 5: Let's Cut Some More Stuff

Now we need to cut two more pieces: the top and the divider.  The top will be the playing surface, or tapa, and the divider will separate the high and low sides/sounds of the bongo.  Honestly I'm not sure why I told you the playing surface is called a "tapa."  I don't actually use that word again in this Instructable.  I think I just wanted to sound cool.

Measure the top edges of your bongo.  Chances are that unless you are a very good craftsman with finely tuned equipment your bongo will not be absolutely square.  No big deal.  If it is obviously off, perhaps it is time to start over.  If it is simply off by a 1/16th of an inch or so like mine was you can proceed with the assurance that no one will be the wiser once it is finished (except those jerks that carry precision measuring equipment in their pockets).  If your top is perfectly square simply measure and cut the 1/8" plywood accordingly.  If it is not, cut the top a bit bigger than need be to accommodate your lackluster carpentry skills and do a bit of sanding.  It will take some elbow grease or a power sander and a deft hand, but such is life, no?  Either way you should cut the top slightly larger than it needs to be and sand it down to meet the sides.  This will give a bit of leeway for mistakes and also look a lot better in the end.  Better to be over the edge than under it.  That's what I always say, at least.  (Okay, I don't actually say that.  Well, I mean, I just did, but I don't say it regularly or anything.)

The divider is about as simple as it gets.  Just measure the inside width of the drum and cut accordingly on your friendly neighborhood miter saw.  I really feel like I should write something else here but I don't know what it would be.  Oh well.  Let's move on.

Step 6: Even Flow

We now have the top cut and ready to glue, but let's first make sure we have a nice, even surface upon which it may rest.  Take a piece of 2 x 4 (or whatever straight scrap wood you have that is longer than the drum is wide) and staple some sand paper to it.  Now move it around while maintaining contact with at least two sides of the drum.  You can use this method to sand the top edges completely flat with each other.  Three cheers for exactitude in simplicity!

Step 7: Gettin' Sticky With It Redux

Ignore the divider for a moment and focus on the top.  Now that you have it cut and the sides of the drum sanded nice and flat you can glue it on.  Squeeze a bunch of glue onto the side edges and slap that puppy home.  Line it up so we're all overhang and no under and clamp it down.  I like to use some flat wood blocks to evenly disperse the weight across as much of the end surfaces as possible, but tonight it's lady's choice, so you're on you own.  I sort of make things up as I go.  You can do the same.  More clamps would be ideal, but this was/is good enough. 

Once you are clamped, wipe off excess glue with a damp cloth and go rough out a few more pages of that novel you've been putting off.

Step 8: Divisiveness Can Be a Good Thing

Remember that divider we cut yesterday?  It's probably too small now, but that's okay.  Test it out.  Does it just barely fit?  Cool.  Is it loose?  Not sure what you did there.  Measure twice, cut once.  Is it too big?  That's cool as well.  We can work with that.  What you want is for it to slide in and stay by itself, at least for the time being.  Use your miter saw and a light touch to make it fit.  Remember, you can always take more off.  Putting it back on is best left to God.  

Throw your divider in there off to one side, turn the drum over and beat on it a bit.  How does it sound?  Does it sound like a bongo?  If so, you are ready to glue.  Does it not sound like a bongo?  If it doesn't, play around with your low to high tone ratio a bit.  My ration was roughly 3:2.  Or maybe 2:1.  I don't really know.  I just played it till it sounded good.  If it never sounds like a bongo no matter what you do, slap another piece of plywood on the bottom, cut a hole in it and call it a birdhouse.  Christmas is coming. . .

Now I know there will be some mathematicians (Yeah, you heard that right.  Music is basically math that can help you land a chick.) who will balk at my method of finding the correct proportion of high and low.  That's cool.  Send me a link to the actual tuning ratio of bongos and I will post it.  I couldn't find it.  Help a brother out.

Step 9: Getting Sticky With It Ad Nauseum

Guess what?  If you guessed gluing and clamping you win a prize!!!  Spread some glue on your divider, slide it home and clamp that sucker. 

Now go wax the cat.  Admit it, he's been looking pretty bad lately.

Step 10: Mr. Sandman, Sand Me a Drum

Let me begin by saying I don't have a router (I'm sure you recall not seeing that in my list of tools).  So basically I have to sand everything with my own two hands and an orbital palm sander.  That being said, I wanted rounded edges that didn't look like a three-year-old did it.  I went to Rockler and got these: Contoured Profile Sanding Grips.  Five and some change later I had nice rounded edges and a sore arm, but I digress.  Between the sander and the grips things turned out rather swimmingly.  But if you have a router you have my permission to use that.  You're welcome.

Step 11: It's Been a While Since I've Staind

I like green.  That is why I chose green stain.  That is all. 

Oh, and let it dry overnight.  Duh.

Step 12: Don't Ask How It's Made

I finished the drum with a couple of coats of tung oil.  This protects and seals and leaves a nice finish.  I also did some additional sanding after applying the stain but before the oil.  At first I was concerned about ruining my stain job, but I rather like the distressed look it gave the drum so I left it.

Applying the oil will raise the grain a bit.  Use steel wool or 220 grit sandpaper to smooth it back out after each coat is applied.  Three coats later and I'm happy with it.  If you like it glossier apply more.  Oh, and don't forget to let it dry completely in between coats and before sanding.  Clean the fish tank, if you need something to do while you're waiting.

Step 13: The Breakdown

So aside from drying time there seems to really only be about 20 minutes of real work involved in the construction of this drum and most of that is sanding.  If you have no other hobbies you might want to borrow a book or enroll in a night class or something.  

You should be able to build this with about half the tools I used and still make something worth playing.  And you should be able to do this even if you are under 18.  Please be careful with power tools, though.  And if you have a nut allergy, tung oil may not be for you.  No really, I'm serious about that one.  Try Salad Bowl Finish.

Here is a video of it in action:



Cheers!