|
octagon post formula
#5393
05/10/05 04:15 AM
|
Joined: Feb 2003
Posts: 135
Collin Beggs
OP
Member
|
OP
Member
Joined: Feb 2003
Posts: 135 |
I am designing some crown post into a frame. Is there a formula for cutting a square timber into an octagon with even measurements on all 8 faces? -Collin
"The lyf so short, the craft so long to lerne." Geoffrey Chaucer (1343-1400)
|
|
|
Re: octagon post formula
#5394
05/10/05 12:03 PM
|
Joined: Oct 1999
Posts: 463
Roger Nair
Member
|
Member
Joined: Oct 1999
Posts: 463 |
Think of the octagon as being composed of eight equally sized wedges rotated around an axis. The angle at the axis is 45. Draw the square, locate the axis, draw a line from axis perpendicular to side of square. The line from center bisects angle of wedge and face of wedge. so,
length of facet = 2 x length of perp x tan 22.5
|
|
|
Re: octagon post formula
#5395
05/10/05 01:15 PM
|
Joined: Feb 2003
Posts: 135
Collin Beggs
OP
Member
|
OP
Member
Joined: Feb 2003
Posts: 135 |
"The lyf so short, the craft so long to lerne." Geoffrey Chaucer (1343-1400)
|
|
|
Re: octagon post formula
#5396
06/19/05 02:29 PM
|
Joined: Nov 2003
Posts: 1,124
Mark Davidson
Member
|
Member
Joined: Nov 2003
Posts: 1,124 |
I recently learned the octagon scale from a stanley square... The octagon scale on my square is on the side opposite the brace table and has the numbers 5,10,15,20 etc.
here is the method to use the scale...
first measure in inches the square stock size you want to make into an octagon while you are doing this, place a center mark on each side of the square stock(e.g. an 8 inch side has a mark at 4") now take a set of dividers and set them to the octagon square scale. for example, if the side of the square stock you have is 8 inches, then set the dividers to measure from 0 to 8 on the octagon scale. now use the dividers to place this measurement onto the square stock by swinging them from the center marks you previously placed. now each side of the square stock should have three marks: the original center mark and two marks from the dividers. now join the marks from the dividers across the corners and you should have an octagon.
|
|
|
|
|
|
|