DIYbanter - View Single Post - Building a cajon, structural strength issue

J. Clarke[_4_]

In article , says...

On 4/9/17 6:05 PM, gdguarino wrote:
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?

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. :-)

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.