Round Table Calculation Help

[dvanvleet]

I am about to start on a round table, but having mental issues with the calculations. I would like the pieces that make the table to be wedge/pie shaped. The table will be 54" in diameter so the circumference is about 170". What I am struggling with is calculating how many individual boards I will need, and at what width. I know that if I use "x" number of boards you divide that by 360 to get the angles, etc, but I'm not sure how wide my boards need to be to determine how many boards I will need. 

Does any of this make sense? Anyone done this before? 

[Gary Beasley]

How wide are the boards you have available to build this? Subtract a bit for waste on the width, add a bit to the circumference figure to allow for waste. Then divide the width into the circumference to get the number of boards, adjust your figures until the result is a whole number. At that point you can divide 360 by that number to get the cutting angle.
One problem you will face is wood movement. Such an arrangement is prone to crack from expansion and contraction unless there is a hole in the middle. Segmenters overcome this with a floating disk when making a bottom for their bowl, disk is not glued in and room for expansion is left in the joint.

Good luck with it! 

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[dvanvleet]

So, let’s say my boards are 6” wide, finished. Dived that by circumference to get approximate number of boards? Play with that to get as close to a whole number of boards? 

[wtnhighlander]

In a recent project journal, I described how I determined the proper angle and widths to cut staves to form a 24-segment tube.

See this Journal.

The same process will apply to your problem, the segment size at the outer diameter of the circle sets the minimum width of each board or panel. If you intend to make the circle of all radial-cut boards, be prepared for a ton of waste. Like, close to 50%. The triangle you cut from each board is equal in are to 1/2 the rectangle of the original board. You can limit this by cutting 2 opposing triangles from one slightly wider board, but the grain will not be truly radial in the resulting circle.

 

Personally, I would probably do radial quadrants, like this (on quadrant illustrated):

[dvanvleet]

Ok, thank you. This helps a lot. I may not go this route because of the waste; I knew there would be a lot, but it would be dang cool. Maybe if I were building it for myself.

[Mark J]

+1 to both of the above, partcularly the remarks about wood movement.  The center of the table must be an open circle to allow for movement.  That circle can be "filled" with a round loose panel, much the same as the loose panel on a cabinet door, but the sector shaped boards can't meet at a point.  

[BillyJack]

One thing I learned when it comes to making furniture. Patterns don't lie. Calculations can easily be incorrect. When I make my tables I don't use calculations I simply draw it out fulls scale and Bingo everything works. I go to home depo and get that cheap wide paper that they sell to put on the floor when remodeling. Or you can get a deal on butcher paper.

Do it once and Get er Done.....

 

[Ronn W]

Awesome work, BJ.

[Mark J]

@BillyJack, are those wedges veneer or thick pieces of solid wood?

[BillyJack]

48 minutes ago, Mark J said:

@BillyJack, are those wedges veneer or thick pieces of solid wood?

1/4 inch birch veneer  mdf 4x8. The same as you would use for cabinet flat panel doors for your kitchen...

 

[Gary Beasley]

Thats one way to get past the wood movement problem, mdf just doesnt. Cutting and gluing veneer to a round cutout plywood will get you there too.

[BillyJack]

I try to stay away from veneer in as much as possible. I've had some larger projects like tables go belly up. It happens from time to time in production and I'mnot amune. ...