Barrel Stave Angles

Can't you get close by laying it out on your AutoCad LT? That will define the angle for you. You'll probably have to do several sections to get close.

Now, remember, I'm a total AC LT novice, like you.

Or, go here:

Building A Stave Drum

Dang Lyn,

Those guys on those sites get real serious. If I had that kind of skill I'd stop net building and start wood working.

I did see something there about an angle setter. It may come in handy for this as well as when I start back on the outside of the house in a few weeks.

Thank you as always.

You are all missing something

150.8" is the circumference (a curve)

the planks are straight and either fit inside or outside the circle when glued together

trigonometry for non-right angle triangles needs to be used to find the width of the planks so that one gets 48" diameter to either the joints or middles of the planks

Here's an example with 5 staves:

... here'a a close-up of a joint:

Say the number of staves is N (calculated as described by Usbport).

In this case, N=5.

The extremal angle A = 360º/N (in this case 360º/5 = 72º)

The angle between the staves is then 180º-A (in this case 180º-72º = 108º)

So the angle to cut, B, is (180º-A)/2 (in this case 108º/2 = 54º).

--------------------------

For N = 30 staves, angle A=360º/30 = 12º; (180º-12º) = 168º, so B = 168º/2 = 84º.

6º = 90º - 84º (confirming the angle Usbport came up with).

Always think a bit of a sketch helps in cases like this.

Thank you all.

6° looks like it will be the target.

I knew you all had me an answer.

Thank you as always.

In theory, it would take ~28.7 planks to go around; 29 would make the barrel just a bit larger than 48". An even number might be handier. Whatever number n of staves, the mitering angle is 180/n.

Thank you for the simple formula.

Well, I see that you've frittered away enough of your time here to be called a guru now.

Guru to you too!

I never even noticed.

Thank you and the rest , for all of the solid information over the last years.

If it were me I would take an old stave and use it for a pattern. You could even drive your truck on it to flatten it out. Just a thought.

Come on Gurus... think! Has everyone forgotten that the sum of the interior angles of a triangle is 180º? Clearly, Usbport's answer is incorrect for interior angles of a polygon. The formula for interior angles, of a polygon, is 180(n-2)/n. The miter angle (for the staves) would be 180(n-2)/2n. I hope you didn't start cutting.

So where's the mistake in #3?

(Actually, your formula yields the same result as both Usbport's and my calculations: 84º (= 90º-6º) - didn't you try it?).

The formula defined in #3 is 360º/2n. Apply that to your example of a pentagon and you get a miter angle of 36º. Your approach is correct because you show that 360º/n is the exterior angle and not the interior angle, as stated in #3, of a polygon and you caculated the miter angle from that.

There may be a language divergence involved here. Table saws nominally cut perpendicularly to the flat dimension(s) of the lumber. The "miter angle" is the amount that you tilt the blade from perpendicular. Thus, in the pentagon example, the angle labeled 54° is not really the "miter angle"; rather the "miter angle" is 36°, the complement of 54°. 180/5 = 36.

We have more or less converged on 30 planks for this cylindrical barrel, with 180/30 = 6° miter angle.

[For some type of goofy feng shui reason, one might argue for 28 planks, 28 being a perfect number, and divisible into equal quadrants. ]

BWT - I was thinking of my cheap'n'cheerful mitre saw jig. I'm no woodworking pro!:

36º = 90º - 54º. Usbport's angle is measured away from perpendicular, while mine is away from parallel. It's just another way of looking at it.

Just a bit of follow-up:

Usbport used the formula 360/2N

I arrived at (180 - (360/N))/2 (putting my steps together).

But these are complementary angles (adding up to 90), so to get them on the same footing, take the complementary angle to "mine", which is:

90 - (180 - (360/N))/2

= (180/2) - (180 - (360/N))/2

= (180/2) - (180/2) + (360/N)/2

= (360/N)/2

= 360/2N

That formula gives the compliment of the miter angle and not the miter angle.

That formula gives the compliment of the miter angle and not the miter angle.

"You're one of the nicest angles I've seen."

"You're the best formula I've come across."

You are indeed a scholar and a gentleman to make someone feel good about a typo. Thanks for the complement... er compliment.

You've just calculated the the 84° as opposed to USBport's 6°. I don't think anyone is going to get mixed up with the two numbers.

6° is a lot smaller than this but I wanted the diagram to be clear.

Incidentally at the moment we are all making a cylindrical barrel. If Netmaker tells us what diameter he wants the ends to be we can tell him what shape to make the staves before putting the angle on the edges.

48" diameter.

Thank you.

So it's just cylindrical, rather than "barrel-shaped"?

Exactly.... 48" top to bottom and about 40" tall.

I want it to store some small remnants of used netting that we recycle into ditty bags and such.....after we rinse and dry. The wood just does not corrode with salt water and looks really good in the shop. Anybody can buy a plastic trash can!

30 staves 5 1/8" wide (point to point will result in a 48" OD, short side to short side = 48" ID) cut at 12 degrees.

Gene

Here's a good site hat may be useful...

danke shun.

Bitte, aber das ist greislig Deutsch!

In the future... Danke Schön

Guten Morgen,

My German is horrible and since my old friend moved back home to the land of dark beer and real sausage, I've had no one left to practice with.

Hope no offense was taken.

tschuss.

Impressed - top site - GA

[not sure about your 'hat' though ]