I am trying to figure the angles needed to cut/weld tube steel into an oblong 1'x7' octagon.?

Answer 1

this one was kinda tough ... I assume that an oblong 1'x7'
octagon is what you get when you "tilt' a stop-sign shaped
thing at an angle to where the width is 7 feet and the
"perceived" height is 1 foot.

If so, cut :

2 pieces = 2.899495 feet
2 pieces = 0.414213 feet
4 pieces = 2.071068 feet

the angles (between the pieces) are 163.7398 degrees
and 106.2602 degrees.

The angles (at the 'ends' of the pieces) are:

4 pieces = 2.071068 feet ("square-off": ie "zero degrees)
2 pieces = 2.899495 feet (16.3 deg 'off-normal')
2 pieces = 0.414213 feet (73.7 deg 'off-normal')

By "off-normal". I mean that a 'square-off' cut is zero
degrees off-normal ... the two longer pieces are fairly
"blunt" and the two short pieces are pretty "sharp", in
that if you put these cuts at the end of a spear, they
would form a sharp point.


if you put the pieces on the floor, you will know
where the angles go.

good luck ...

here's the BASIC program to determine these values:
/*************************/
pii = 355 / 113

a = 1 + 2 ^ .5

PRINT "a = "; a

b = 1 / a

PRINT "1/a = "; 1 / a

b7 = 7 * b

PRINT "b7 = "; b7

c = (7 - b7) / 2

d = (1 - b) / 2

PRINT "a,b,c,d="; a; b; c; d

thet = ATN(d / c)

PRINT "theta = "; thet

dthet = 360 * (thet / pii)

PRINT "dthet="; dthet

alpha = 180 - dthet

PRINT "alpha = "; alpha

psi = 90 - dthet

PRINT "psi = "; psi

beta = 180 - psi

PRINT "beta ="; beta

e = (c ^ 2 + d ^ 2) ^ .5

PRINT "e = "; e

Answer 2

In any shape with more than 3 sides, the sum of the angles equal 360 degrees. In an equalateral octagon, each angle should be 45 degrees. You should cut each piece at 22.5 degrees.

Answer 3

they are both right and wrong. yes, the the angle of the center would be 45 degrees, but not the cut. as they stated, their is 360 degrees in a circle. but their is also 180 degrees in an triangle. if you take 45 degrees away, one is left with 135 degrees. split that into two sides of a triangle and you have your answer of 67.5 degrees. cut every side at 67.5 degrees

Answer 4

8 X 2 = 16
360 / 16= 22.5 degrees

16 cuts, 2 per piece, length 6 the same , two longer and equal,