?on miter cut.

Bruce I looked at your drawing Do you not see your mistake ??????? Even your drawing shows 54 Degrees. Seeing that you cut your MITER off a fence or table saw that is set to 90 degrees from your blade being set at 0 Degrees. DO YOU NOT GET 36 FROM SUBTRACTING 54 FROM 90 ?????????? Is that not what you would have to set your saw to ????? 36 degrees is your miter try actually building something for once. You are why CAD programs get such a bad name. CAD programs do give the right information it is how one is able to interpret the information give to be able to put it into practice.

CHRIS

to quote you "lets make a bet" then lets go and build one to prove it I will wager $ 100.00 Canadian to prove my point that you have to set your miter to 36 Degrees will you?

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Reply to
Chris Melanson
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Please go and BUILD a pentagone to see that your MITER has to be 36 degreesand figure out what I mean. You have no clue what you are talking about. You are the one who is "(obviously) working so far from your area of expertise."

CHRIS

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Reply to
Chris Melanson

Sorry for the spelling forgot to run through spell checker before sending the last post.

CHRIS

Reply to
Chris Melanson

Ummm, so am I ... but since you got it right the first time, you obviously weren't included in "these days" with regard to education.

Reply to
Swingman

Go back and read again what I took exception to.

Reply to
Swingman

Did you even read the OP.????

and yes "All closed polygons have angles that equal 360 degrees, with the single exception of the triangle family, where those angles equal

180 degrees" as Quoted from CJ

So will you make the bet ? And try making a pentagon setting your saw to 54 degrees or will you apologise and accept that the answer is 36 degrees.

CHRIS

Reply to
Chris Melanson

Yes, but only part of the story. Exterior angles equal 72, interior angles equal 108.

The right answer, but you appeared to be going about it for the wrong reason:

As stated, it doesn't have to. What you are leaving out, or failing to mention, is the concept of complementary angles.

Reply to
Swingman

The only trouble with that quote is, it's false.

The sum of the exterior angles of any closed polygon of n sides is (n - 2) * 180 degrees.

180 for a triangle 360 for a square 540 for a pentagon 720 for a hexagon and so on.

Miter gauge settings measure the difference from 90 degrees (e.g. to make a cut at a right angle, you set the gauge at 90 - 90 = 0 degrees). So to make the proper 54-degree cuts for a mitered joint at the corner of a regular pentagon, you set your miter gauge to 90 - 54 = 36 degrees -- but this cuts a

54-degree angle, *not* a 36-degree angle. Don't believe me? Make the cut. Then get a protractor and measure the actual angle.

-- Regards, Doug Miller (alphageek-at-milmac-dot-com)

For a copy of my TrollFilter for NewsProxy/Nfilter, send email to autoresponder at filterinfo-at-milmac-dot-com

Reply to
Doug Miller

No it doesn't. It consists of five 108-degree angles.

No, it's an absolute falsehood. The sum of the exterior angles of any closed polygon of n sides is (n - 2) * 180 degrees. It's 360 *only* for four-sided figures, where (4 - 2) * 180 = 2 * 180 = 360.

Which means a 54-degree angle on each piece. Combined, those make a 108-degree angle.

Get a pencil, paper, and protractor, and draw it out yourself.

-- Regards, Doug Miller (alphageek-at-milmac-dot-com)

For a copy of my TrollFilter for NewsProxy/Nfilter, send email to autoresponder at filterinfo-at-milmac-dot-com

Reply to
Doug Miller

What am I leaving out ? The concept of complementary angles is that mating MITERS of 36 degrees result in a angle of 72 degrees and in order to obtain a pentagon you have 5 sides and 5 * 72 is 360. But a MITER of 54 degrees would result in an angle of 108 and 5 * 104 = 540 not 360 which is what a circle consist of in degrees.So how would you obtain a closed polygon consisting of 540 degrees? Can you not see that? The "OP" asked "My wife would like a 5 sided planter. Just thinks it would look cute?? I am not a wood worker but, have access to a compound miter saw. What degree would I need to cut the 2x4's to achieve this? They will each be 27" long.

CHRIS

"Swingman" wrote in message news:qd-dnTN-k snipped-for-privacy@giganews.com...

All closed polygons have angles that equal 360 degrees, with the

Reply to
Chris Melanson

Yes, but you obviously didn't.

I don't have to ... the angle you are actually cutting when you set your saw to cut 36 is the complementary angle, 54 degrees.

Go out to the shop, cut a 36 degree angle on your saw, then measure the angle you just cut.

Reply to
Swingman

Please read the "OP" and then go and build one I am getting sick and tired of people without the concept of actually building something trying to tell me how it is done. You do END up with a 54 Degree angle but do not set your saw for a 54 degree MITER cut. Please learn the difference between the two.

CHRIS

Reply to
Chris Melanson

If I was wrong then I'd apologise, as I'm not, then I won't.

The OP asked "What degree would I need to cut the 2x4's"

He would need to set his compound miter saw to 36 degrees...

Graham

Reply to
Graham Walters

Tell us again how the sum of the interior angles of a polygon must be 360 degrees. I get a kick out of it.

The sum of the interior angles of a pentagon is 540 degrees. Each interior angle is 540/5 = 108 degrees. half of that is 54 degrees.

If your measuring instrument is providing the right-angle compliment, then you want to cut at 90-54 = 36 degrees. Note that this is not the usual meaning of "complimentary angle" in geometry, where it refers to the 180 degree compliment:

\ \ \ 180-A \ A

-------------\---------------- A \ 180-A \ \ \

Many mitre saws will provide a scale showing the angle from 90 degrees (0 is a right angle cut) and the right- angle compliment (90 degrees is a right angle cut).

In this case, you want 54 degree cuts on the legs of the pentagon so that 108 degree interior angles will be formed. And yes, 108 does not divide evenly into

360 degrees, and there's no reason why it should.

Figuring out how to use your mitre saw's dial is not the crux of the problem. It's knowing what interior angle you need in order to form a given regular polygon.

Quick, what's the required mitre cut for a nonagon?

Reply to
Greg Neill

No, that is correct.

Reply to
Leon

Thank you, that is exactly what I have been saying. (Did you read my post before you replied?) As my post makes abundantly clear, I know the difference perfectly well. It is now clear that you do also, although your sloppy use of terminology in previous posts made it appear that you did not.

Now just add up those 54-degree angles -- one at each end of each of five pieces, making ten in all -- and get 540 degrees as the sum of the exterior angles in a pentagon, and we'll both be on the same page.

:-)

-- Regards, Doug Miller (alphageek-at-milmac-dot-com)

For a copy of my TrollFilter for NewsProxy/Nfilter, send email to autoresponder at filterinfo-at-milmac-dot-com

Reply to
Doug Miller

Reply to
Chris Melanson

I do it one step simpler. I count the amount of cuts needed, 10, and divide into 360, 36 degrees.

For a square, 8 cuts into 360, 45 degrees.

For a 20 piece unit, 40 cuts into 360, 9 degrees.

Reply to
Leon

Ahhh , now we're getting somewhere. ... therefore, the correct answer to the OP's question of what angle the cut needs to be:

... is 54 degrees, NOT 36, as you have heretofore been insisting..

The answer to the unasked question "how to cut a 54 degree angle on a miter saw" is to set it to the complementary angle of 36 degrees.

Reply to
Swingman

Hey ... at least it is ON TOPIC!

Reply to
Swingman

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