Workshop Math & 'rithmetic
The
following formulas may prove useful to you for determining various
values within the workshop environment.
If you have or know of one which you think belongs here, then
please Email me with
it, and I'll stick it on the list. Accordingly, if you find a
formula to be in error let me know.
AREAS OF:
CIRCLE: Pi*r2
SQUARE: A2
RECTANGLE: B*D
OCTAGON: 2*d2*tan.22 1/2 degs. =.828*d2
(where d = distance from side to side).
HEXAGON: 3/2*d2tan.30degs=.866d2 (where
d = distance from side to side).
ELLIPSE: (axis)a * (axis)b / .7854
VALUES
OF:
PI: 3.14159275359 (3.14 is normally considered to be close enough).
BOARD FOOT: Thickness (in inches) x Width (in inches) x Length
(in feet) / 12
1 U.S. GALLON (water) = 8.33 lbs = 231 cu.in = 0.13368 cu.ft.
REGULAR POLYGONS:
Suppose
you want to determine the length of a side for any given regular
polygon. If you have a diameter the finished polygon shall be,
then this table will assist you in determining the length of the
polygon's sides.
Example: Suppose you wanted to make a wooden octagon picture frame
that had a diameter of 21" but wanted to find the length of one
side of the octagon. You first select the number of divisions
of the circle (in this case 8) then, under the multiplier column
find the multiplier .38268. Now, for every 1" in diameter (in
this case 21") you multiply by the multilier - 21 x .38268 = 8.03628
or 8 1/32".
Let's take a moment and chat about Metric...
I find the metric system in these Great United States of America to be offensive.
Further, I find the fact of it being shoved down our throats
to be intrusive to say the least. And, lastly, I reserve the
right to loathe the metric system. So, I'm afraid you won't find anything here that going to help you with anything metric.
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