Mitre question???

On Tue, 19 Jul 2005 10:22:14 -0400, [email protected] (JAKE) wrote:

>I want to make an 8 sided table top. What would he mitre angle be for
>the skirting?

Asked and answered just recently, so my first impression was that this
is a troll. A Google would bring the result. However, since it has
been answered several ways, I'll suggest yet another method, still
based on the same principles.

8 sides = 8 triangles to the center.
The center angle is then divided 8 ways = 360/8 = 45
Each triangle has two angles at the outside that are equal, and the
angles in a triangle add to 180, so they add to 180 - 45 = 135. Being
equal, they are each 67.5 degrees.

Do the same sort of calculation for any number of sides [oteh thsan
8.]

In article <[email protected]>,
Unquestionably Confused <[email protected]> wrote:
>Leon wrote:
>
>>>sides all equal length and angles all the same. Rectangle would also fit
>>>here even though the sides differ so _I_ would define a rectangle with its
>>>90 degree corners as a regular polygon but that might be stretching it.
>>>
>>
>>
>> Ok that is not correct in reference to the equasion only working on Regular
>> polygons. All sides do have to be equal angles but all pieces DO NOT have
>> to be the same length.
>
>But if you have a polygon (more than four sides), how can you have equal
>angles AND differing sides. I submit that you can't.

You *are* confused! Albeit somewhat understandably so. <grin>

Try a hexagon, with sides of 1,2,3,1,2,3 All the angles can be 60 degrees.

>
>Imagine a pentagon with four sides being 2' long and 1 side 3' long.
>Show me the equal angles<g>


With a pentagon, it *is* also doable, Take a regular pentagon, and draw
lines parallel to two _adjoining_ faces, at say halfway down the sides.
You get a shape vaguely reminiscent of a squatty ice-cream cone. The
bottom of length "a", two 'sides' of length "b", and the two top parts
of length "c". All inside angles _are_ the same 72 degree measure.

Quantitatively, given the bottom (a) as of length 10, the sides (b) are
then of length (5), and the 'top' parts (c) are of length 8.0902+.

"Oldun" <[email protected]> wrote in message
news:[email protected]...
> Why not just divide 360 by the number of sides. This gives you the angle
> of
> each joint. Mitre each side joint at half this angle and assemble.
>
> 8 sides = 360/8=45
> 45/2=22.5
>
> There, just mitre at 22.5 degrees.
>
> Oldun

If you read higher up in the thread I made that same BASIC suggestion a few
days back. Actually I divide the sides by the number of end cuts needed.

More simply put, 360 divided by double the sides.

360/(4 sides x 2 end cuts) = 45
360/(8 sides x 2 end cuts) = 22.5
360/(60 sides x 2 end cuts) = 3

On Tue, 19 Jul 2005 13:03:40 -0400, "gw" <[email protected]> wrote:

>180 / (number of sides) has always worked for me. What's with all the
>complicated equations??

That will work. The math is how to get there.

If the table top is accurately cut, then 22.5degrees

John

On Tue, 19 Jul 2005 10:22:14 -0400, [email protected] (JAKE) wrote:

>I want to make an 8 sided table top. What would he mitre angle be for
>the skirting?

On 7/24/2005 10:45 AM Unquestionably Confused mumbled something about
the following:
> Odinn wrote:
>
>>> If you read higher up in the thread I made that same BASIC suggestion
>>> a few days back. Actually I divide the sides by the number of end
>>> cuts needed.
>>>
>>> More simply put, 360 divided by double the sides.
>>>
>>> 360/(4 sides x 2 end cuts) = 45
>>> 360/(8 sides x 2 end cuts) = 22.5
>>> 360/(60 sides x 2 end cuts) = 3
>>>
>>>
>>
>> This only works with shapes of 4 or more sides, it doesn't work for a
>> triangle.
>
>
> Actually it ONLY works for equilateral triangles and REGULAR polygons.
>
> Try your method or his (same thing really) on a parallelogram, trapezoid
> or rhombus and get back to us.
>
>
>
>
Okay

360 / (3 x 2) = 60
An equilateral triangle has 60 degree angles. I must not be getting it,
because I can't seem to match 2 60 degree angles and end up with a 60
degree angle.

--
Odinn
RCOS #7
SENS(less)

"The more I study religions the more I am convinced that man never
worshipped anything but himself." -- Sir Richard Francis Burton

Reeky's unofficial homepage ... http://www.reeky.org
'03 FLHTI ........... http://www.sloanclan.org/gallery/ElectraGlide
'97 VN1500D ......... http://www.sloanclan.org/gallery/VulcanClassic
Atlanta Biker Net ... http://www.atlantabiker.net
Vulcan Riders Assoc . http://www.vulcanriders.org

rot13 [email protected] to reply

"Odinn" <[email protected]> wrote in message
news:[email protected]...
> On 7/24/2005 10:58 AM Leon mumbled something about the following:
>> "Odinn" <[email protected]> wrote in message
>> news:[email protected]...
>>
>>
>
> and how do I come up with 120 degrees? 360 ( 3 sides X 2) is the equation
> we were using doesn't come up with 120.

Well. I will admit that it does become a bit tricky at this point. Because
most saws will not tilt the blades much past 45 degrees, a 60 degree bevel
has to be accomplished by rotating the board 90 degrees and has it to be cut
at the 30 degree setting. This leaves you with a complimentary result angle
of 60 degrees. I'll post a PDF file to alt.binaries. picture.woodworking
with a CAD drawing of the set up and how the angles are "conjured up".

Secret Squirrel wrote:
...
> Which of course is the same thing. 30 and 60 degree angles are
> complimentary.

And on top of liking each other, they're "complementary" in forming a
right angle... :)

Secret Squirrel wrote:
...
>
> 22.5 and 67.5 are complimentary angles. ...

You've the wrong "compliment" here (BTW, I didn't post until after I
read the second time, just to be sure...). :)

Angles are "complementary", we give each other "compliments" for good
work, etc., ... :)

Here is the way to figure any of these questions

For every side add 180 degrees, after 4 sides. example 6 sides....360(for
the four sides then 180 (for fifth side) + 180 (for sixth side) add
up...360 + 180 +180 =720 Now divide by number of sides....720/6
=120...divide 120 in half because you are mitering 60 degrees.



Now let's try it on the 8 sided table.


360 for the square + 180 + 180 + 180 + 180 + 1080

1080/8= 135
135/2=67.5 degrees If you flipp the board over it equals 22.5 degrees.
"Leon" <[email protected]> wrote in message
news:[email protected]...
>
> "JAKE" <[email protected]> wrote in message
> news:[email protected]...
>>I want to make an 8 sided table top. What would he mitre angle be for
>> the skirting?
>>
>
> 22.5
>



----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups
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Why not just divide 360 by the number of sides. This gives you the angle of
each joint. Mitre each side joint at half this angle and assemble.

8 sides = 360/8=45
45/2=22.5

There, just mitre at 22.5 degrees.

Oldun

Thanks to all for adding confusion to what I thought was a simple
explaination, even if it had been mentioned previously.

I do wonder how many WRECKERS actually work with wood. Some obviously do and
are very experienced. But, judging by the number and frequency of letters I
suspect the only tools some use are a keyboard and mouse!!

Oldun

Leon wrote:

> "John "The Toymaker" Gilham" <[email protected]> wrote in message
> news:[email protected]...
>
>>Here is the way to figure any of these questions
>>
>>For every side add 180 degrees, after 4 sides. example 6
>>sides....360(for the four sides then 180 (for fifth side) + 180 (for sixth
>>side) add up...360 + 180 +180 =720 Now divide by number of
>>sides....720/6 =120...divide 120 in half because you are mitering 60
>>degrees.
>
>
> Wrong
>
> A 6 sides table would require 30 degree cuts. 360/ (6 sides x 2) = 30
>
>
I'm not sure which is more intriguing: the fact that the question was
brought up by a "woodworker", or the confusion it has engendered in this
thread...

Dave

"gw" <[email protected]> wrote in message =
news:[email protected]...
|=20
| "Leon" <[email protected]> wrote in message
| news:[email protected]...
| >
| > "John "The Toymaker" Gilham" <[email protected]> wrote in message
| > news:[email protected]...
| > > Here is the way to figure any of these questions
| > >
| > > For every side add 180 degrees, after 4 sides. example 6
| > > sides....360(for the four sides then 180 (for fifth side) + 180 =
(for
| sixth
| > > side) add up...360 + 180 +180 =3D720 Now divide by number of
| > > sides....720/6 =3D120...divide 120 in half because you are =
mitering 60
| > > degrees.
| >
| > Wrong
| >
| > A 6 sides table would require 30 degree cuts. 360/ (6 sides x 2) =
=3D 30
| >
| >
|=20
| 180 / (number of sides) has always worked for me. What's with all the
| complicated equations??
|=20
|=20

Rube Goldberg ring a bell???

--=20
PDQ

Glen wrote:

> I admit, it has been a long time since I took geometry, but I kinda
> remember Mr. Darby telling us that triangles had ony 189 degrees.
>
> Glen

TYPO ALERT

Make that 180 degrees!

Glen

Leon wrote:
> "Unquestionably Confused" <[email protected]> wrote in message
> news:[email protected]...
>
>>Leon wrote:
>>
>>
>>>Ok that is not correct in reference to the equasion only working on
>>>Regular polygons. All sides do have to be equal angles but all pieces DO
>>>NOT have to be the same length.
>>
>>But if you have a polygon (more than four sides), how can you have equal
>>angles AND differing sides. I submit that you can't.
>>
>>Imagine a pentagon with four sides being 2' long and 1 side 3' long. Show
>>me the equal angles<g>
>
>
> Ok Yeah with an odd number of sides shape you are going to have a problem.

There, you said it, sort of. Odd number of sides

> Ok, what I am trying to say here is that assuming a regular shaped 8 sided
> table the angles are all the same for the 8 pieces to connect. Length does
> not have to be the same and angles are all the same. I post another picture
> on a.b.p.w. to illustrate what I am talking about. Perhaps I do not
> understand exavtly what you are talking about.

I think the problem with all of this is we're (all)attempting to make
one rule fit all situations. Obviously it doesn't work on all triangles
and your rule that allows different length sides on a polygram but keeps
the angles identical throughout will only work on a polygon with an EVEN
number of sides. Once you have five, seven or nine sides to your
polygon then you're right back to length of sides and angles must be
identical.

"Unquestionably Confused" <[email protected]> wrote in message
news:[email protected]...

>
> Actually it ONLY works for equilateral triangles and REGULAR polygons.

How do you define REGULAR polygons?

On 7/24/2005 12:25 PM Leon mumbled something about the following:
> "Odinn" <[email protected]> wrote in message
> news:[email protected]...
>
>>I've done triangles, but I had to do lap joints, since I couldn't come up
>>with the cut, no matter how I positioned the board. Obviously, I was
>>doing something wrong if it can be done.
>
>
>
> You absolutely have to do them backwards to normal thinking including the
> angles. Did you check my PDF file on A.B.P.W. ? That illustrates how to
> cut the angles for a triangle on the TS.
>
>
Yes, I checked it out, but something still isn't clicking on the angles
for me. Not to worry, I don't have to worry about triangles very often,
so it isn't that critical :)

--
Odinn
RCOS #7
SENS(less)

"The more I study religions the more I am convinced that man never
worshipped anything but himself." -- Sir Richard Francis Burton

Reeky's unofficial homepage ... http://www.reeky.org
'03 FLHTI ........... http://www.sloanclan.org/gallery/ElectraGlide
'97 VN1500D ......... http://www.sloanclan.org/gallery/VulcanClassic
Atlanta Biker Net ... http://www.atlantabiker.net
Vulcan Riders Assoc . http://www.vulcanriders.org

rot13 [email protected] to reply

"John "The Toymaker" Gilham" <[email protected]> wrote in message
news:[email protected]...
> Here is the way to figure any of these questions
>
> For every side add 180 degrees, after 4 sides. example 6
> sides....360(for the four sides then 180 (for fifth side) + 180 (for sixth
> side) add up...360 + 180 +180 =720 Now divide by number of
> sides....720/6 =120...divide 120 in half because you are mitering 60
> degrees.
>
>
>
> Now let's try it on the 8 sided table.
>
>
> 360 for the square + 180 + 180 + 180 + 180 + 1080
>
> 1080/8= 135
> 135/2=67.5 degrees If you flipp the board over it equals 22.5 degrees.

Geez you made that complicated. The simple equation to any sided table is
simply take the number of sides multiply by 2 and divide that number in to
360. Period.

More simply put, 360 divided by double the sides.

360/(4 sides x 2) = 45
360/(8 sides x 2) = 22.5
360/(60 sides x 2) = 3

Odinn wrote:

>> If you read higher up in the thread I made that same BASIC suggestion
>> a few days back. Actually I divide the sides by the number of end
>> cuts needed.
>>
>> More simply put, 360 divided by double the sides.
>>
>> 360/(4 sides x 2 end cuts) = 45
>> 360/(8 sides x 2 end cuts) = 22.5
>> 360/(60 sides x 2 end cuts) = 3
>>
>>
>
> This only works with shapes of 4 or more sides, it doesn't work for a
> triangle.

Actually it ONLY works for equilateral triangles and REGULAR polygons.

Try your method or his (same thing really) on a parallelogram, trapezoid
or rhombus and get back to us.

Leon wrote:

>>sides all equal length and angles all the same. Rectangle would also fit
>>here even though the sides differ so _I_ would define a rectangle with its
>>90 degree corners as a regular polygon but that might be stretching it.
>>
>
>
> Ok that is not correct in reference to the equasion only working on Regular
> polygons. All sides do have to be equal angles but all pieces DO NOT have
> to be the same length.

But if you have a polygon (more than four sides), how can you have equal
angles AND differing sides. I submit that you can't.

Imagine a pentagon with four sides being 2' long and 1 side 3' long.
Show me the equal angles<g>


> With the formula that I use all pieces do not have to be the same length.
> All parallel pieces have to be equal length.

Okay. With this one, assume it's a parallelogram. Four sides are
parallel (by definition) with the opposing side. Angles differ on two
corners.

Gotta hand it to you, you sure know how to make things complicated.
"John "The Toymaker" Gilham" <[email protected]> wrote in message
news:[email protected]...
> Here is the way to figure any of these questions
>
> For every side add 180 degrees, after 4 sides. example 6
sides....360(for
> the four sides then 180 (for fifth side) + 180 (for sixth side) add
> up...360 + 180 +180 =720 Now divide by number of sides....720/6
> =120...divide 120 in half because you are mitering 60 degrees.
>
>
>
> Now let's try it on the 8 sided table.
>
>
> 360 for the square + 180 + 180 + 180 + 180 + 1080
>
> 1080/8= 135
> 135/2=67.5 degrees If you flipp the board over it equals 22.5 degrees.
via Encryption =----

"Leon" <[email protected]> wrote in message
news:[email protected]...
>
> "John "The Toymaker" Gilham" <[email protected]> wrote in message
> news:[email protected]...
> > Here is the way to figure any of these questions
> >
> > For every side add 180 degrees, after 4 sides. example 6
> > sides....360(for the four sides then 180 (for fifth side) + 180 (for
sixth
> > side) add up...360 + 180 +180 =720 Now divide by number of
> > sides....720/6 =120...divide 120 in half because you are mitering 60
> > degrees.
>
> Wrong
>
> A 6 sides table would require 30 degree cuts. 360/ (6 sides x 2) = 30
>
>

180 / (number of sides) has always worked for me. What's with all the
complicated equations??

On 7/24/2005 10:58 AM Leon mumbled something about the following:
> "Odinn" <[email protected]> wrote in message
> news:[email protected]...
>
>
>>360 / (3 x 2) = 60
>>An equilateral triangle has 60 degree angles. I must not be getting it,
>>because I can't seem to match 2 60 degree angles and end up with a 60
>>degree angle.
>
>
> An equilateral triangle has 60 degree angles at the end of each peice.
> That is because you end up with a 120 degree angle when matching up 2 60
> degree angles. Add 3 120 degree angles up and you get 360 degrees. An
> equilateral triangle.
>
>

and how do I come up with 120 degrees? 360 ( 3 sides X 2) is the
equation we were using doesn't come up with 120.

--
Odinn
RCOS #7
SENS(less)

"The more I study religions the more I am convinced that man never
worshipped anything but himself." -- Sir Richard Francis Burton

Reeky's unofficial homepage ... http://www.reeky.org
'03 FLHTI ........... http://www.sloanclan.org/gallery/ElectraGlide
'97 VN1500D ......... http://www.sloanclan.org/gallery/VulcanClassic
Atlanta Biker Net ... http://www.atlantabiker.net
Vulcan Riders Assoc . http://www.vulcanriders.org

rot13 [email protected] to reply

On 7/24/2005 11:35 AM Leon mumbled something about the following:
> "Odinn" <[email protected]> wrote in message
> news:[email protected]...
>
>>On 7/24/2005 10:58 AM Leon mumbled something about the following:
>>
>>>"Odinn" <[email protected]> wrote in message
>>>news:[email protected]...
>>>
>>>
>>
>>and how do I come up with 120 degrees? 360 ( 3 sides X 2) is the equation
>>we were using doesn't come up with 120.
>
>
> Well. I will admit that it does become a bit tricky at this point. Because
> most saws will not tilt the blades much past 45 degrees, a 60 degree bevel
> has to be accomplished by rotating the board 90 degrees and has it to be cut
> at the 30 degree setting. This leaves you with a complimentary result angle
> of 60 degrees. I'll post a PDF file to alt.binaries. picture.woodworking
> with a CAD drawing of the set up and how the angles are "conjured up".
>
>
I've done triangles, but I had to do lap joints, since I couldn't come
up with the cut, no matter how I positioned the board. Obviously, I was
doing something wrong if it can be done.

--
Odinn
RCOS #7
SENS(less)

"The more I study religions the more I am convinced that man never
worshipped anything but himself." -- Sir Richard Francis Burton

Reeky's unofficial homepage ... http://www.reeky.org
'03 FLHTI ........... http://www.sloanclan.org/gallery/ElectraGlide
'97 VN1500D ......... http://www.sloanclan.org/gallery/VulcanClassic
Atlanta Biker Net ... http://www.atlantabiker.net
Vulcan Riders Assoc . http://www.vulcanriders.org

rot13 [email protected] to reply

"Odinn" <[email protected]> wrote in message
news:[email protected]...
> On 7/24/2005 9:58 AM Leon mumbled something about the following:
>>
>
> This only works with shapes of 4 or more sides, it doesn't work for a
> triangle.

It certainly does work with a triangle. However you will be hard pressed to
find a saw that will cut at 60 degrees. The solution if using a TS would be
to set the saw at 30 degrees and put the board on end and run through the
saw.

"Odinn" <[email protected]> wrote in message
news:[email protected]...
>>
> I've done triangles, but I had to do lap joints, since I couldn't come up
> with the cut, no matter how I positioned the board. Obviously, I was
> doing something wrong if it can be done.


You absolutely have to do them backwards to normal thinking including the
angles. Did you check my PDF file on A.B.P.W. ? That illustrates how to
cut the angles for a triangle on the TS.

"Oldun" <[email protected]> wrote in message
news:[email protected]...
> Thanks to all for adding confusion to what I thought was a simple
> explaination, even if it had been mentioned previously.
>
> I do wonder how many WRECKERS actually work with wood. Some obviously do
> and
> are very experienced. But, judging by the number and frequency of letters
> I
> suspect the only tools some use are a keyboard and mouse!!
3

Yeah.. LOL.

RE: Subject

My 80+ year old, at the time, high school math teacher, Olive Bowers,
all 4'-10" and 85 lbs of her would roll over in her grave observaving
this discussion.

You guys can do better.

Lew

Leon wrote:
> "Unquestionably Confused" <[email protected]> wrote in message
> news:[email protected]...
>
>
>>Actually it ONLY works for equilateral triangles and REGULAR polygons.
>
>
> How do you define REGULAR polygons?

sides all equal length and angles all the same. Rectangle would also fit
here even though the sides differ so _I_ would define a rectangle with
its 90 degree corners as a regular polygon but that might be stretching it.

Also, an "Oops, my bad" is owed to Odinn. I got hung up on the angle
feature and what I was thinking was equilateral triangle, three equal
angles, divide them by 2 and that's your cut. Won't work on any other
triangle AFAIK.

None of the methods discussed here will work on parallelograms,
trapezoids, or rhombi (sp?)

Unquestionably Confused (in
[email protected]) said:

| Leon wrote:
|| "Unquestionably Confused" <[email protected]> wrote in message
|| news:[email protected]...
||
||| Leon wrote:
|||
|||
|||| Ok that is not correct in reference to the equasion only working
|||| on Regular polygons. All sides do have to be equal angles but
|||| all pieces DO NOT have to be the same length.
|||
||| But if you have a polygon (more than four sides), how can you
||| have equal angles AND differing sides. I submit that you can't.
|||
||| Imagine a pentagon with four sides being 2' long and 1 side 3'
||| long. Show me the equal angles<g>
||
||
|| Ok Yeah with an odd number of sides shape you are going to have a
|| problem.
|
| There, you said it, sort of. Odd number of sides
|
|| Ok, what I am trying to say here is that assuming a regular shaped
|| 8 sided table the angles are all the same for the 8 pieces to
|| connect. Length does not have to be the same and angles are all
|| the same. I post another picture on a.b.p.w. to illustrate what
|| I am talking about. Perhaps I do not understand exavtly what you
|| are talking about.
|
| I think the problem with all of this is we're (all)attempting to
| make one rule fit all situations. Obviously it doesn't work on all
| triangles and your rule that allows different length sides on a
| polygram but keeps the angles identical throughout will only work
| on a polygon with an EVEN number of sides. Once you have five,
| seven or nine sides to your polygon then you're right back to
| length of sides and angles must be identical.

I don't think so. I've posted an example to abpw.

--
Morris Dovey
DeSoto Solar
DeSoto, Iowa USA
http://www.iedu.com/DeSoto/solar.html

"gw" <[email protected]> wrote in message
news:[email protected]...
>>
>
> 180 / (number of sides) has always worked for me. What's with all the
> complicated equations??
>

That will work also but for me it is easier to remember 360 as that forms a
complete circle vs. a straight line. Actually 360 divided by the total
number of cuts works also.

"Unquestionably Confused" <[email protected]> wrote in message
news:MjOEe.378>>
>> How do you define REGULAR polygons?
>
> sides all equal length and angles all the same. Rectangle would also fit
> here even though the sides differ so _I_ would define a rectangle with its
> 90 degree corners as a regular polygon but that might be stretching it.
>

Ok that is not correct in reference to the equasion only working on Regular
polygons. All sides do have to be equal angles but all pieces DO NOT have
to be the same length.
With the formula that I use all pieces do not have to be the same length.
All parallel pieces have to be equal length.



> Also, an "Oops, my bad" is owed to Odinn. I got hung up on the angle
> feature and what I was thinking was equilateral triangle, three equal
> angles, divide them by 2 and that's your cut. Won't work on any other
> triangle AFAIK.

I agree.

"John "The Toymaker" Gilham" <[email protected]> wrote in message
news:[email protected]...
> Here is the way to figure any of these questions
>
> For every side add 180 degrees, after 4 sides. example 6
> sides....360(for the four sides then 180 (for fifth side) + 180 (for sixth
> side) add up...360 + 180 +180 =720 Now divide by number of
> sides....720/6 =120...divide 120 in half because you are mitering 60
> degrees.

Wrong

A 6 sides table would require 30 degree cuts. 360/ (6 sides x 2) = 30

"Leon" wrote in message

> How do you define REGULAR polygons?

There is only one definition: all angles in a REGULAR polygon are equal.

The sum of the _exterior_ angles of ANY polygon is 360 degrees.

The sum of the _interior_ angles of ANY polygon = 180° (n-2) where
n=number of sides

There shouldn't be much more any one needs. LOL

--
www.e-woodshop.net
Last update: 7/23/05

"Guess who" <[email protected]> wrote in message
news:[email protected]...
> On Tue, 19 Jul 2005 10:22:14 -0400, [email protected] (JAKE) wrote:
>
> >I want to make an 8 sided table top. What would he mitre angle be for
> >the skirting?
>
> Asked and answered just recently, so my first impression was that this
> is a troll. A Google would bring the result. However, since it has
> been answered several ways, I'll suggest yet another method, still
> based on the same principles.
>
> 8 sides = 8 triangles to the center.
> The center angle is then divided 8 ways = 360/8 = 45
> Each triangle has two angles at the outside that are equal, and the
> angles in a triangle add to 180, so they add to 180 - 45 = 135. Being
> equal, they are each 67.5 degrees.
>
> Do the same sort of calculation for any number of sides [oteh thsan
> 8.]
>

As you can see by using math you've come up with a completly wrong answer.
By using common sense the angle for the skirt cuts would be 22.5. This is
not rocket science.

"Leon" <[email protected]> wrote in
news:[email protected]:

>
> "John "The Toymaker" Gilham" <[email protected]> wrote in message
> news:[email protected]...
>> Here is the way to figure any of these questions
>>
>> For every side add 180 degrees, after 4 sides. example 6
>> sides....360(for the four sides then 180 (for fifth side) + 180 (for
>> sixth side) add up...360 + 180 +180 =720 Now divide by number of
>> sides....720/6 =120...divide 120 in half because you are mitering 60
>> degrees.
>
> Wrong
>
> A 6 sides table would require 30 degree cuts. 360/ (6 sides x 2) = 30
>
>

Which of course is the same thing. 30 and 60 degree angles are
complimentary.

"Battleax" <[email protected]> wrote in
news:[email protected]:

>
> "Guess who" <[email protected]> wrote in message
> news:[email protected]...
>> On Tue, 19 Jul 2005 10:22:14 -0400, [email protected] (JAKE) wrote:
>>
>> >I want to make an 8 sided table top. What would he mitre angle be
>> >for the skirting?
>>
>> Asked and answered just recently, so my first impression was that
>> this is a troll. A Google would bring the result. However, since it
>> has been answered several ways, I'll suggest yet another method,
>> still based on the same principles.
>>
>> 8 sides = 8 triangles to the center.
>> The center angle is then divided 8 ways = 360/8 = 45
>> Each triangle has two angles at the outside that are equal, and the
>> angles in a triangle add to 180, so they add to 180 - 45 = 135.
>> Being equal, they are each 67.5 degrees.
>>
>> Do the same sort of calculation for any number of sides [oteh thsan
>> 8.]
>>
>
> As you can see by using math you've come up with a completly wrong
> answer. By using common sense the angle for the skirt cuts would be
> 22.5. This is not rocket science.
>
>
>

Which as I mentioned to another poster is the same thing.
22.5 and 67.5 are complimentary angles. It's just a matter of which side
of the line you're cutting.

[email protected] (JAKE) wrote in news:19918-42DD0C96-850@storefull-
3134.bay.webtv.net:

> I want to make an 8 sided table top. What would he mitre angle be for
> the skirting?

As stated, this question cannot be answered, as there are infinitely
many possible arrangements of 8 sides which result in a closed
surface.

However, assuming that what you really meant was "I want to make
an octagonal table top", the answer is 22 1/2 degrees.

John

"Leon" <[email protected]> wrote in
news:[email protected]:

>
> "Secret Squirrel" <[email protected]> wrote in message
> news:[email protected]...
>> "Leon" <[email protected]> wrote in
>> news:[email protected]:
>>
>>>
>>> "John "The Toymaker" Gilham" <[email protected]> wrote in message
>>> news:[email protected]...
>>>
>>
>> Which of course is the same thing. 30 and 60 degree angles are
>> complimentary.
>
> Actually you probably are not going to find a 60 degree setting on any
> saw. So uh you would set to 30 degrees.
>
>

of course not. The point was that someone, I'm not sure who, said that
the math was wrong. The math was absolutely correct. Understanding that
30 and 60 degree angles are complementary is necesarry for practical
application, but doesn't make his original statement incorrect.

"Odinn" <[email protected]> wrote in message
news:[email protected]...

>
> 360 / (3 x 2) = 60
> An equilateral triangle has 60 degree angles. I must not be getting it,
> because I can't seem to match 2 60 degree angles and end up with a 60
> degree angle.

An equilateral triangle has 60 degree angles at the end of each peice.
That is because you end up with a 120 degree angle when matching up 2 60
degree angles. Add 3 120 degree angles up and you get 360 degrees. An
equilateral triangle.

"Unquestionably Confused" <[email protected]> wrote in message
news:[email protected]...
>
> I think the problem with all of this is we're (all)attempting to make one
> rule fit all situations. Obviously it doesn't work on all triangles and
> your rule that allows different length sides on a polygram but keeps the
> angles identical throughout will only work on a polygon with an EVEN
> number of sides.

Correct

Once you have five, seven or nine sides to your
> polygon then you're right back to length of sides and angles must be
> identical.
>

Actually not all have to be the same length as illustrated by Morris Dovey's
post in a.b.p.w.

On 7/24/2005 9:58 AM Leon mumbled something about the following:
> "Oldun" <[email protected]> wrote in message
> news:[email protected]...
>
>>Why not just divide 360 by the number of sides. This gives you the angle
>>of
>>each joint. Mitre each side joint at half this angle and assemble.
>>
>>8 sides = 360/8=45
>>45/2=22.5
>>
>>There, just mitre at 22.5 degrees.
>>
>>Oldun
>
>
> If you read higher up in the thread I made that same BASIC suggestion a few
> days back. Actually I divide the sides by the number of end cuts needed.
>
> More simply put, 360 divided by double the sides.
>
> 360/(4 sides x 2 end cuts) = 45
> 360/(8 sides x 2 end cuts) = 22.5
> 360/(60 sides x 2 end cuts) = 3
>
>

This only works with shapes of 4 or more sides, it doesn't work for a
triangle.

--
Odinn
RCOS #7
SENS(less)

"The more I study religions the more I am convinced that man never
worshipped anything but himself." -- Sir Richard Francis Burton

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rot13 [email protected] to reply

On Tue, 19 Jul 2005 22:03:58 GMT, "Leon"
<[email protected]> wrote:

>
>"Secret Squirrel" <[email protected]> wrote in message
>
>> Which as I mentioned to another poster is the same thing.
>> 22.5 and 67.5 are complimentary angles. It's just a matter of which side
>> of the line you're cutting.
>
>And I will mention again that you will not find 67.6 degrees on your saw.

What saw are you using? All of my saws have a range of 90 degrees to
45 degrees (maybe a little less in some cases) To get 22.5 requires
cutting a complementary angle or using a jig.

"Secret Squirrel" <[email protected]> wrote in message

> Which as I mentioned to another poster is the same thing.
> 22.5 and 67.5 are complimentary angles. It's just a matter of which side
> of the line you're cutting.

And I will mention again that you will not find 67.6 degrees on your saw.

"Secret Squirrel" <[email protected]> wrote in message
news:[email protected]...
>>
>>
>
> of course not. The point was that someone, I'm not sure who, said that
> the math was wrong. The math was absolutely correct. Understanding that
> 30 and 60 degree angles are complementary is necesarry for practical
> application, but doesn't make his original statement incorrect.


Well in one of his examples his math was wrong.

He went on to give another examples of
Now let's try it on the 8 sided table.


360 for the square + 180 + 180 + 180 + 180 + 1080

1080/8= 135
135/2=67.5 degrees If you flipp the board over it equals 22.5 degrees.

That does not add up. He adds 360+180+180+180+180+1080 which would normally
= 2160 not 1080.

A reasonable person would gibe an answer to the saw setting to come up with
the end result. He simply made this way too complicated for some one that
could not determine the answer in the first place. Typically and or at
least I was always taught to make the equasion as simple as possible. Why
not use a formula that gives the angle setting found on the saw?

"Unquestionably Confused" <[email protected]> wrote in message
news:uoOEe.381>
>
> No, Odinn's right. ANY triangle is a three-sided polygon. The sum of the
> angles of a triangle is 180 degrees.

Yes I agree to a point. My formula of dividing the total number of cut, "2
on each end of 3 pieces" into 360 still works on a triangle but the set up
on the saw has to be bit different since a TS will not tilt its blade 60
degrees in relation to the fence. You have to rotate the piece of wood to
be parallel to the fence and the 30 degree setting on the bevel will give
you a complementary 60 degree angle result. If the blade would tilt to 60
degrees in relation to the fence you could cut it in the traditional mannor.


> The END of each side of an equilateral triangle is a 30 degree angle which
> meets another 30 degree angle to come up with 60 degrees.

Correct but again my formula works for the saw bevel setting or perceived
saw bevel setting. Since the saw will not tilt past 45 degrees you have to
rotate the board parallel with the fence to end up with what the same angle
that the saw would cut if it could tilt to 60 degrees during a normal
setting with the work laying flat on the TS top.
I posted a CAD drawing in PDF format to a.b.p.w. You will have to open the
file to see the drawing.

"Secret Squirrel" <[email protected]> wrote in message
news:[email protected]...
> "Leon" <[email protected]> wrote in
> news:[email protected]:
>
>>
>> "John "The Toymaker" Gilham" <[email protected]> wrote in message
>> news:[email protected]...
>>
>
> Which of course is the same thing. 30 and 60 degree angles are
> complimentary.

Actually you probably are not going to find a 60 degree setting on any saw.
So uh you would set to 30 degrees.

Leon wrote:
> "Odinn" <[email protected]> wrote in message
> news:[email protected]...
>
>
>>360 / (3 x 2) = 60
>>An equilateral triangle has 60 degree angles. I must not be getting it,
>>because I can't seem to match 2 60 degree angles and end up with a 60
>>degree angle.
>
>
> An equilateral triangle has 60 degree angles at the end of each peice.
> That is because you end up with a 120 degree angle when matching up 2 60
> degree angles. Add 3 120 degree angles up and you get 360 degrees. An
> equilateral triangle.
>
>
I admit, it has been a long time since I took geometry, but I kinda
remember Mr. Darby telling us that triangles had ony 189 degrees.

Glen

Leon wrote:
> "Odinn" <[email protected]> wrote in message
> news:[email protected]...
>
>
>>360 / (3 x 2) = 60
>>An equilateral triangle has 60 degree angles. I must not be getting it,
>>because I can't seem to match 2 60 degree angles and end up with a 60
>>degree angle.
>
>
> An equilateral triangle has 60 degree angles at the end of each peice.
> That is because you end up with a 120 degree angle when matching up 2 60
> degree angles. Add 3 120 degree angles up and you get 360 degrees. An
> equilateral triangle.


No, Odinn's right. ANY triangle is a three-sided polygon. The sum of
the angles of a triangle is 180 degrees.

The END of each side of an equilateral triangle is a 30 degree angle
which meets another 30 degree angle to come up with 60 degrees.

I'm not Unquestionably Confused for nuttin' <g>

"Unquestionably Confused" <[email protected]> wrote in message
news:[email protected]...
> Leon wrote:
>
>> Ok that is not correct in reference to the equasion only working on
>> Regular polygons. All sides do have to be equal angles but all pieces DO
>> NOT have to be the same length.
>
> But if you have a polygon (more than four sides), how can you have equal
> angles AND differing sides. I submit that you can't.
>
> Imagine a pentagon with four sides being 2' long and 1 side 3' long. Show
> me the equal angles<g>

Ok Yeah with an odd number of sides shape you are going to have a problem.

>
>
>> With the formula that I use all pieces do not have to be the same length.
>> All parallel pieces have to be equal length.
>
> Okay. With this one, assume it's a parallelogram. Four sides are
> parallel (by definition) with the opposing side. Angles differ on two
> corners.

Ok, what I am trying to say here is that assuming a regular shaped 8 sided
table the angles are all the same for the 8 pieces to connect. Length does
not have to be the same and angles are all the same. I post another picture
on a.b.p.w. to illustrate what I am talking about. Perhaps I do not
understand exavtly what you are talking about.

>

"JAKE" <[email protected]> wrote in message
news:[email protected]...
>I want to make an 8 sided table top. What would he mitre angle be for
> the skirting?
>

22.5

JAKE wrote:
> I want to make an 8 sided table top. What would he mitre angle be for
> the skirting?
>
Tell me you are kidding.

Dave