In article , marc rosen wrote:
On May 21, 9:31=A0pm, Jay Pique wrote:
So I've got one big plank of walnut out of which I'd like to make a
round table. =A0I've determined that since the plank is 12x96 I have
1152 square inches of area, which equates to just over a 38" diameter
table, (ignoring the realities of loss due to saw kerfs and the
aesthetics of infinitely narrow strips.) =A0Now assume that I rip the
plank into 3 strips of 4" - what's the biggest diameter I can get? =A0Is
there any sort of formula I can use to see what my options are?
Thanks.

JP

Hey JP, (left arm is in a cast following surgery. all typing from
this point will be lower case)
i don't follow your reasoning very well. how thick is it? why not
cross cut it to 32 long, rip and edge joint tp 11 wide each, and edge
glue. you'd have a 33x32 plank which would produce an almost 32 inch
diameter table. the waste would be minimal compared to making the
strips you refered to and cross cutting and gluing stuff up.

Sorry, but that's incorrect. The waste from this method would in fact be a
very large fraction of the total. He's starting with, as he noted, 1152 square
inches; a circle with a diameter of 32 inches has an area of only 804 square
inches, so the waste is 348 sq in or a bit over 30%. That's not "minimal" by
any reasonable definition.

Ripping into 4" strips (actually about 3-7/8 after kerfs and edge jointing)
wastes only 3/8" x 96" = 4 square inches. Obviously there will be more wasted
than that when the strips are cut to length and glued up, but it won't be
anywhere near 30%.

Jay -- I'm sure there is a formula, but it won't be simple to derive. You can
get an approximation, though, from the following:

The largest circle theoretically possible, with zero waste, would have radius
= sqrt ( 1152 / pi ) = 19.15 -- so a bit over 38" diameter is the theoretical
maximum.

I think as a practical matter you're going to be limited to 36" diameter (nine
strips). Best to draw it out on graph paper, I think.