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Alcarte 02-06-2011 12:11 AM

Angle of cut
 
I have limited material and I need the angle I should be mitering for octagon shape

Jackofall1 02-06-2011 12:14 AM

360 / 8 = 45
45/2 = 22.5

Daniel Holzman 02-06-2011 10:02 AM

Doesn't work that way Jack. See http://www.articlesbase.com/home-imp...es-193794.html

for a complete description of the procedure to find miter angles for polygons. In this case, the correct answer is 1/2 (135) = 67.5 degrees.

Joe Carola 02-06-2011 10:12 AM

Quote:

Originally Posted by Daniel Holzman (Post 585671)
Doesn't work that way Jack. See http://www.articlesbase.com/home-imp...es-193794.html

for a complete description of the procedure to find miter angles for polygons. In this case, the correct answer is 1/2 (135) = 67.5 degrees.

The saw setting for the miter if he's cutting trim is 22.5. If he was cutting a jack rafter for an octagon roof the saw setting would be 67.5.

jlmran 02-06-2011 10:15 AM

Jack is correct. OP didn't ask what to set his saw at, he asked what miter to make.

del schisler 02-06-2011 10:29 AM

Quote:

Originally Posted by Alcarte (Post 585563)
I have limited material and I need the angle I should be mitering for octagon shape

If you are cutting a octagon like for a school house clock with 8 pieces they are 22.5 degree's cut. I used to mfd school house clock's and they were 22.5 degree's than and still now. Just set the saw and cut. No use to get into the long math of the 67 and 90 stuff just confusion. set at 22.5 and cut for the 8 sides.

Joe Carola 02-06-2011 10:32 AM

1 Attachment(s)
Quote:

Originally Posted by jlmran (Post 585676)
Jack is correct. OP didn't ask what to set his saw at, he asked what miter to make.

Quote:

Originally Posted by Alcarte
I have limited material and I need the angle I should be mitering for octagon shape

He says he needs the angle for mitering an octagon shape. If he's talking about cutting casing or a flat stock for an octagon shape table the miter angle to set the miter saw on is 22.5.

If he's cutting a jack rafter for an octagon roof the saw setting is 67.5.

In plan view the angle is running at 67.5, but what good does that do for the OP for cutting that angle. He needs to set the miter saw at 22.5.

Joe Carola 02-06-2011 10:38 AM

Quote:

Originally Posted by jlmran (Post 585676)
Jack is correct. OP didn't ask what to set his saw at, he asked what miter to make.

So, you would tell him to make a 67.5 miter on all 8 cuts? What angle would you tell him to set the saw at?

jlmran 02-06-2011 02:09 PM

Depends on what type of saw. He could be using a hand saw.

masterofall 02-06-2011 02:20 PM

22.5 X 16 faces = 360

del schisler 02-06-2011 03:22 PM

we beat this one to death
 
well we beat this one to death. cut 22.5 on each piece for a stop sign

mrgins 02-07-2011 10:41 AM

dear god! It's 22.5!!

Big N8 02-07-2011 12:34 PM

what is it <.< >.>








OOO I see it is 22.5 LOL

WirelessG 02-07-2011 01:18 PM

With a universal reverser saw, the angle would be 167.5, but if you adjust the fence 90 degrees, using an opposite hand oppositizer, the angle would be 77.5

masterofall 02-07-2011 06:01 PM

Quote:

Originally Posted by WirelessG (Post 586381)
With a universal reverser saw, the angle would be 167.5, but if you adjust the fence 90 degrees, using an opposite hand oppositizer, the angle would be 77.5


Sory your wrong, even with a universal reverser saw the angle is 157.5 as you are subtracting the remainder from the 90 - 22.5 = 67.5 + 90 now your doing a 180 flip so your minus half of that and then subtract the remainder of the 90 - 67.5 = 22.5, with the opposite hand oppositer the angle would be 67.5. There would be no need to adjust the fence 90 degrees if one just spatialy reverses the process you can then set the miter at 22.5:whistling2:


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