"Jay Pique" wrote in message
...
On May 21, 10:44 pm, (Doug Miller) wrote:
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.- Hide quoted text -

I'm pretty sure I'm going to rip the plank into ~4" strips, so that
will make my job easier. I'm going to play around in SketchUp, like
someone mentioned, to see about exact cut-lengths. I could even try
to make my cuts on an angle to help minimize waste. I wonder if the
big millwork shops that make (lots of) round tables glue up and cut to
minimize waste? Hmmm....

Thanks for the replies, everyone.


I worked in a table shop for a while, we primarily made round
red oak pedestal tables.

We cut all the material for the tops the same length, after glue up
the tops were sanded in the square and cut to round with a bandsaw,
the corners were saved to make glue ups for feet,
very little material was wasted and there was no complex
cutting or gluing for the tops.

There was one semi retired
guy that made roll front bread boxes, shelf brackets and other
widgets and gizmos out of some of the waste, most of what left
as waste was sawdust and shavings.

basilisk