- posted on November 30, 2005, 3:30 am

Hi, I would like to make a round waste basket that is 12" round at the top and 8" at the bottom. I will be using 2"x1/4" hardwood slats. Is there some simple formula that I can use to figure out how wide the bottom part of the slats will be tapered, the angle to cut the edge and how many slats will be needed? Many Thanks, John

- posted on November 30, 2005, 5:24 am

If you approximate it as a circle, then

Circ = pi* Dia

Using 2" slats, this gives 12*pi/2.85 slats.

So plan on 19 slats.

You could use the circle approximation and be pretty close, but we may as well get exact.

If you draw a triangle from the centre of a 19-sided polygon to the centre of an edge and the outer point of an edge, the central angle will be 360/(2*19) or 9.47 degrees. Remember this for later, as it's also the bevel you'll need for the sides of the slats.

Trig says that

sin(theta) = opposite/hypotenuse

so

sin(theta) = s/2r

where

theta = central angle s = length of the side r = distance from outer vertex to centre

plugging in a slat width of 2", we get a max diameter of 12.15" which is pretty close to what you asked for.

For the bottom, if we start with a desired max diameter of 8", this gives a slat width of 1.317".

As mentioned above, you'll want to bevel the edges at 9.47 degrees from vertical.

Chris

- posted on November 30, 2005, 7:41 pm

Thank you, looks like I need to go back to school and learn math all
over again, LOL
Thanks Again,
John

On Tue, 29 Nov 2005 23:24:06 -0600, Chris Friesen

On Tue, 29 Nov 2005 23:24:06 -0600, Chris Friesen

- posted on November 30, 2005, 5:34 am

John wrote:

Hi John, Pi times 12 = 37.699. Pi times 8 = 25.133. Divide 37.699 by the actual width of the slats to find how many slats you'll need. The bottom of the slat will be 0.666 times the width of the top of the slat. Without knowing the height of the basket, I can't give you the angle. -Mike

Hi John, Pi times 12 = 37.699. Pi times 8 = 25.133. Divide 37.699 by the actual width of the slats to find how many slats you'll need. The bottom of the slat will be 0.666 times the width of the top of the slat. Without knowing the height of the basket, I can't give you the angle. -Mike

- posted on November 30, 2005, 7:43 pm

Thank you Mike, the height would be 12".
Regards,
John

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