barrel stave angles

Hi
I am trying to build some small barrels. I want to make a jig so that I can make a few at one time.. I am having a problem with the angle layout. Lets say I am building a barrel of 10 in with 15 starves if all the staves widths are equal its easy to compute the angle 360/15=24 degrees divded by 2 (1 for each side) = 12 degrees. However I have looked at many commercial barrels and I see that the staves are off different widths. They build them that way for more strength and economy so more wood can be used with less scrap. So my question is will they still use the 12 degree angle or do the modify the angle for each piece. I would imagine that it would be to time consuming in a commercial operation to keep changing thier machine jigs. So how does one firgure out the angle if the number of pieces change when the diameter of the barrel stays the same
thanks
Steve ross

Hi Steve,

Welcome...

First, I am hoping that a moderator will move this to a forum that will see more traction. This should be in green woodworking...I think?

Coopering a barrel of any size will be a matter of more than just "one set angle." This is much an art as it is a "geometry exercise." As you have noted...staves are of different widths...and...tapered to facilitate the shape that is a "barrel." and like buckets, tubes, sinks, troughs, and related containers the angles can vary greatly...

They build them that way for more strength and economy so more wood can be used with less scrap.

Actually they build them that way for strength...and "economy" is just a fringe perk to the process..."Coopers" are frugal folk to say the least...

So my question is will they still use the 12 degree angle or do the modify the angle for each piece.

They are custom to each stave and following a "format angle" that the Cooper has selected for the give shape (aka curve) of the container. If building something like an wood form of 風呂 ofuro( Japanese soaking tub) you may find a more consistent geometry to follow in some of the designs...However, even these Ki oke furo 木桶風呂 (Wood Tub Bath) or teppōburo 鉄砲風 (Gun Bath) are as much art and artistry of technique as they are any "set geometry" per se...

I would imagine that it would be to time consuming in a commercial operation to keep changing their machine jigs. So how does one figure out the angle if the number of pieces change when the diameter of the barrel stays the same...

Finding and learning directly from an experience cooper, and/or a lot of "experimenting" with your own techniques of green woodworking...

There is some pretty good (and not so good) info out on the "web" covering this subject...

Good Luck,

j

here is a link to the first class I found...

Coopering Buckets

Coopering Barrels