# Building a cajon, structural strength issue

For the uninitiated, a cajon is a percussion instrument, essentially a wood en box with one thin side and a hole in the opposite side. I'm a keyboard p layer, but have recently developed a hankering to dabble in percussion. Plu s, I have a pile plywood scraps lying around.
I've seen various plans online, and I'm sure that there are any number of s ound-related variables to consider, but I'm mostly here to ask about struct ural strength.
One plan I saw calls for a box 12"x12"x18" tall, made with 1/2" plywood. Th e wrinkle is, one plays a cajon while *sitting* on it. And some of us wanna -be percussionists have put on a few pounds over a lifetime. I'm wondering about the strength of what is effectively a five-sided 1/2" ply box (the fr ont side is made with very thin ply, maybe 1/8")for say, 250 pounds. Will i t need corner braces? Or 3/4" ply?
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On 4/9/17 6:05 PM, gdguarino wrote:

As a drummer and woodworker, I've avoided the cajon like the plague because it's just another gadget that will be piling up the corners of pawn shops and used music stores like the eleventy-zillion djembes that preceded the cajon.
However, we often underestimate the strength of the average plywood box. With a 4-sided plywood rectangle, you have tremendous strength that is only weakened by lateral, diagonal force. That diagonal force is countered by the sides of the "cube" similar to how plywood sheathing provides the diagonal resistance to wind in the shear wall construction of a house.
You have nothing to worry about. Even the thin side of the cajon is enough to provide enough diagonal strength. They are all made that way and I haven't seen one collapse yet.
The more important factor to consider is what type of hardwood veneers to use in constructing your cajon. Use a wood that will provide and clean, consistent, even burning for when you inevitability end up making a camp fire out of the thing after the fad is over. :-)
--

-MIKE-

"Playing is not something I do at night, it's my function in life"
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Just a note but when I want to mess with somebody I'll take an empty medium sized corrugated box, lay a piece of plywood on top, and use it for a step- stool. People who haven't seen me do it don't believe that it works.
Compared to corrugated cardboard, half inch ply is _very_ strong.
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On 4/9/2017 8:53 PM, -MIKE- wrote:

Thanks for the construction tips. That makes sense.
As for the rest, I've also been a musician my whole life, keyboards mostly. But I've also always been a "drummer"; drumming on everything (except drums). I tap on desks, doors, appliances, the steering wheel of my car, garbage cans, bottles, various body parts, you name it. I search for the "sweet" spots, listening for different tones. Odd? Yeah, I know.
Being a keyboard player with a home recording setup, I now have access to an absurd number of increasingly-convincing sampled sounds; notably including drums and percussion. Even got myself a dedicated pad controller - a vast improvement over trying to program percussion on a keyboard.
But I'm finishing out my sixth decade this year, and I find that I want to try some new things, one of which is adding some genuine percussion to my recordings. The samples are pretty great these days, and are recorded better than I'm likely to do at home. But the parts I play live have a little more variability to them, replacing some of the "perfection" with "feel". I like that.
Over the last couple of months I've acquired a set of Bongos, a Darbuka and - yes - a Djembe. The Djembe is already on a recording. Adds a touch of realism, even though my playing is still inexpert. That's another great thing about these computer recording setups; I only need to get the part right *once*. :) So far it's the Bongos that I seem to have the most natural affinity for.
Fad or not, Cajons have been around for a long time. I first became aware of them quite a while back on a Ruben Blades record. I like the sound, at least on record. My attempts in the music store have not been inspiring - yet. But I happen to have a bunch of pieces of prefinished 1/2" Birch ply courtesy of the discard pile behind a cabinet shop near my house; enough to build a cajon. I figure a few hours work should yield a cajon for just the expense of a piece of 1/8" ply. I can probably even get a broken snare from my drummer, if I decide to put snares in.
If it sucks, or I suck at playing it, there's not much loss.
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Who da thunk the lid off a Brinkmann smoker and a big breasted gal with legs spread across a wooden box could sound this good!

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On Mon, 10 Apr 2017 02:23:57 +0000, Spalted Walt

Sound? Wooden box (splinters?)?
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On Sun, 9 Apr 2017 16:05:42 -0700 (PDT), gdguarino

Here's a vid for you.
Otherwise go south, get a good strong cajun woman to sit on and.... :)
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For the uninitiated, a cajon is a percussion instrument, essentially a wooden box with one thin side and a hole in the opposite side. I'm a keyboard player, but have recently developed a hankering to dabble in percussion. Plus, I have a pile plywood scraps lying around.
I've seen various plans online, and I'm sure that there are any number of sound-related variables to consider, but I'm mostly here to ask about structural strength.
One plan I saw calls for a box 12"x12"x18" tall, made with 1/2" plywood. The wrinkle is, one plays a cajon while *sitting* on it. And some of us wanna-be percussionists have put on a few pounds over a lifetime. I'm wondering about the strength of what is effectively a five-sided 1/2" ply box (the front side is made with very thin ply, maybe 1/8")for say, 250 pounds. Will it need corner braces? Or 3/4" ply?
1/2" should be more than enough.
When I was a photographer I had some posing boxes made; varying sizes, 1/4" ply. Never a problem.
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On Sunday, April 9, 2017 at 6:05:44 PM UTC-5, gdguarino wrote:

oden box with one thin side and a hole in the opposite side. I'm a keyboard player, but have recently developed a hankering to dabble in percussion. P lus, I have a pile plywood scraps lying around.

sound-related variables to consider, but I'm mostly here to ask about stru ctural strength.

The wrinkle is, one plays a cajon while *sitting* on it. And some of us wan na-be percussionists have put on a few pounds over a lifetime. I'm wonderin g about the strength of what is effectively a five-sided 1/2" ply box (the front side is made with very thin ply, maybe 1/8")for say, 250 pounds. Will it need corner braces? Or 3/4" ply?
My granddaughter wanted on. Made it out of Home Depot bargain plywood and it has held up well. Are you planning on putting the snare in it?
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On 4/12/2017 7:52 PM, Dr. Deb wrote:

I'm guessing I'm a little larger than your granddaughter, but I'm reasonably persuaded that a 1/2" ply box will be robust enough.
As for the snares, I tend to prefer the no-snare sound, but I'm doing this for fun and experimentation with different sounds, so I'll probably add in a "switchable" snare. I don't watch that much of Woodworking for Mere Mortals, but I have to say that his "mechanism" looks awfully easy to accomplish; no reason not to add on that feature.
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I hafta agree. I wanted to ship a Fender Champ lap steel from CA to NY:
<
https://www.well.com/~wellvis/steels/Fender/FenderChamp-StudioDeluxe.jpg

A local shipping store wanted to charge me \$80USD fer packaging (bubble wrap=\$60USD! All cardboard!). I made a small box of a single sheet of 1/2" ply. I bought some foam from our local suplus store, put it all together with brass wood screws. Cost? \$40USD. This about 12 yrs ago.
Bottom line: I weighed about 260 lbs and could jump up and down on sed box, all day long, with zero ill effects. ;)
nb
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Last year I finally got around to purchase a Cajon on discount. I had searched around locally and found only one model that I truly liked which was at Sam Ash. I played around with it for two weeks and decided I still was not satisfied with the sound. I decided maybe this summer I would try and build my own.
I searched for plans and ideas and there are lots out there. Some really good YouTube videos too. Many I have watched use plywood with good results. Including weight handling. Check YouTube for ideas.
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On Sun, 9 Apr 2017 16:05:42 -0700 (PDT) snipped-for-privacy@gmail.com wrote:

what kind of ply is it
would expect only the active drum head part to make up most of the sound signature so the box could be what ever holds you up
looking at other designs can give ideas and inspiration
make sure whatever you use will not splinter horribly should it fail
maybe add a cajones protector on the top of the cajon
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I've started building the cajon. The top and bottom are 3/4 prefinished birch ply; the sides and back are 1/2". The different thicknesses were mostly chosen because that's what I had available in scrap lumber, but it also allowed me to feel more comfortable about rabbeting the top and bottom to accept the side pieces and the back.
https://www.flickr.com/photos/gdguarino/33947797231/in/album-72157682631167556/
The rod, by the way, will have snare wires attached to it and the knob will allow me to engage the snares or disengage them.
The back also fits into rabbets. I decided to attach it with pocket screws for now. . If it seems like there is air leakage around the edges, I'll either glue it or caulk the joints.
https://www.flickr.com/photos/gdguarino/33719061480/in/album-72157682631167556/
As predicted by some of you here, it feels more than stout enough, even without the front piece.
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wrote:

Will it have 4 feet attached ? to allow bottom to resonate a little ? Perhaps an easy experiment, when it's all done - to see if it makes a difference. John T.
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On 4/19/2017 12:29 PM, snipped-for-privacy@ccanoemail.ca wrote:

My sense of things tells me that the materials for the five "non-striking" sides of the cajon don't affect the sound as much. But I have indeed put rubber feet on it; the room it will most often be used in has porcelain tile.
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On 4/19/17 10:54 AM, Greg Guarino wrote:

Looking good. You may be aware of this but the thicker the wood, the higher the pitch. That's one reason for having a thinner "batter" side. Also, think about a port. Do some reading on it. A port with usually add some low end and resonance.
--

-MIKE-

"Playing is not something I do at night, it's my function in life"
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On 4/19/2017 12:53 PM, -MIKE- wrote:

The front piece (the "tapa") will be 1/8" birch ply, because that's what they had at the crafts store near me. :)
Funny you should mention a "port", I was thinking about that, even though I have not seen any cajons that have one. I found a floor drain flange at HD that mates with 4" PVC pipe. I might give it a try, depending on how the cajon sounds once it's complete. I see that someone actually sells an add-on for cajons, but it's only about 5" long.
I also wondered about possibly adding piece of ply inside, parallel to the tapa, extending from the top of the cajon almost to the bottom, giving the air a longer path to the hole in the rear.
For me, this may be one of those "getting there is half the fun" situations. It might sound great without any tweaking, but if not (which seems likely), I'm up for some experimentation.
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Should anyone be interested, I did some more work on the Cajon, which is now temporarily finished.
Cajons come in at least two major varieties: with snare and without. The "snare" variety has either snare-drum snares or some guitar strings stretched across the back of the striking surface to add a "snare-drum'-like quality to the higher-pitched sound you get by striking near the edge.
I made my Cajon with a set of snares that you can turn on or off. They were mounted on a rod that can be turned so as to have the snares contact the striking surface or not.
https://flic.kr/p/SSaL2y
(photo is shown with the striking surface - a piece of 1/8" plywood - removed)
I got the idea for the switchable snare from a Woodworking for Mere Mortals video and used his placement of the rod. But there was a problem. The angle of the snares to the striking surface was too great, the snares only touched near their tips and didn't produce much sound.
I took a look at a couple of commercially-made cajons and saw that the snares - like on a snare drum - were essentially laying lightly on the back of the striking surface.
I didn't want to move the rod at this stage; I'd have had to fill in the holes that hold it in place. Instead, I made a couple of "brackets" that attach to the rod and hold a narrow piece of 1/2" ply that in turn holds the snares.
https://flic.kr/p/TWZpCB https://flic.kr/p/TyBArq
This now works pretty well. The snares, when "engaged" are nearly parallel to the striking surface, and they produce the desired sound. In addition, the sound can be adjusted a little bit my rotating the knob to vary the "pressure" on the snares. Here's a poor photo inside the cajon:
https://flic.kr/p/U9xV56
In the "disengaged" position the snares "jingle" softly from the vibration of the box. I intend to install a piece of foam weatherstripping for the snares to rest against when they are not in use. That will probably wait until I decide on another experiment or two that I might try to alter the sound.
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On Mon, 24 Apr 2017 12:50:02 -0400

does that mean you reserve the right to tweak it here and there

like his videos low drama and little fanfare
not saying i always agree with his methods
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