?on miter cut.

Aww, come on. There have been much worse threads than this one.

Reply to
Lawrence Wasserman
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A word to the wise, and do take it kindly:

There is no sense the blind leading the blind. Get her a good tutor! "Pounding" never works; you have to stimulate some interest. A good tutor should be able to do that as well.

Dan.

Reply to
Danny Boy

You guys are making this way too complicated. I'd love to get this group together to play 'telephone'.

Some careless use of terminology has muddied the picture here. The idea of 'interior' and 'exterior' angles is just confusing. There is only one angle one needs to be concerned with, and that is the (bevel angle) between the center of a regular polygon and any vertex.

The answer to the original question should be obvious by drawing a circumscribed circle about the polygon. Then draw 'spokes' from the center to each vertex. You will have created a bunch of triangles as well as circle segments. As we know from fifth grade math class, the sum of the angles of all circle segments always adds up to 360 degrees. This is the only thing that always adds up to 360 degrees. The sum of the perimeter angles between the polygon segments does not add up to 360 degrees except for 4-sided polygons.

So, with your little sketch, note that the angle between the vertexes and the center of a pentagon is 72 degrees, which also happens to be

360/5. Since your segment includes two such bevel angles, each is 36 degrees. This is the bevel angle. Period. End of story.

Imagine what would have happened if the original poster had wanted to build a gazebo...

Nice to see everybody staying on topic, though...

John

John Paquay snipped-for-privacy@insightbb.com

"Building Your Own Kitchen Cabinets"

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Glory and Passion No Longer in Fashion The Hero Breaks His Blade. -- Kansas, The Pinnacle, 1975

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Reply to
John Paquay

Yet the story continues.... ;-)

You've now got five isosceles triangles (two equal length sides). The angle at the apex is 72 degrees as you noted. Since the sum of the angles of any triangle must be 180 degrees, this leaves

180 - 72 = 108 degrees for the other two angles of each triangle.

Since the other two angles are equal, they must each be

108/2 = 54 degrees. This is the angle between an outside face and the mitre cut's face.

To cut this 54 degree angle on a mitre saw, set the saw to

90 - 54 = 36 degrees, since the saw's scale has 0 degrees as a right angle, and measures deflection from the perpendicular.
Reply to
Greg Neill

Not quite! You said.... "angle between the vertexes and the center of a pentagon is 72 degrees", which is quite correct. However, that is not the angle in question. The angles being cut are at the vertex, not the center. The angle at the center,subtracted from the triangle [180 degrees] formed by that and the angles at the vertices makes them each half of 180 - 72, or 108/2 = 54 degrees. Two cuts together form the angle at the vertex, 108 degrees.

By the way, has anyone here made those cuts, or made the item in question? It's not too difficult to do with a few scraps.

Dan.

Reply to
Danny Boy

I agree, but my head hurts now. Thanks for bringing me home, though.

John

John Paquay snipped-for-privacy@insightbb.com

"Building Your Own Kitchen Cabinets"

formatting link
Glory and Passion No Longer in Fashion The Hero Breaks His Blade. -- Kansas, The Pinnacle, 1975

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Reply to
John Paquay

It's bang on, in fact.

An octagon can take another turn if you draw a square within a square at 45. Then it's easy to see the inside angle of the octagon as 135. So two cuts would each be 67.5 as you say.

Using the formula:

Each inside angle is (8-2)*180 / 8 = 3/4 of 180 = 135 ...etc.

Dan.

Reply to
Danny Boy

You're preaching to the choir! ;>)

Reply to
Swingman

Ah, Charlie, 'twasn't math problems that turned this thread into the train wreck it became, 'twas a lack of English. (Or rather a lack in that branch of English study involving a simple willingness to look up definitions.)

Seems to me that Chris's been making an ass of himself, (with all the bravado of one who's ignorance has him convinced he's right), simply because he insists on calling a locomotive a caboose.

Michael (not a choo-choo engineer)

Reply to
Michael Baglio

For some real entertainment, come on back when ya need a bootleg "Best of Fine Woodworking" CD.

It's like 54 vs. 36, but with _ethics._

Michael

Reply to
Michael Baglio

Michel you seem to not of read the thread very well. I do not know how many times I stated that the miter saw was to be set at 36 degrees and the resulting angle would be 54 degrees. Seems to me you need to brush up on your reading skills some what. As far as you saying "I am making an ass of myself". I feel that when some one lacks the capability to express himself with having to name call other people it shows a level of intellect that I neither have the time or the patience for. A newsgroup should be a forum for people to have a free exchange of ideas and opinions. But it is exactly your reaction why people turn away from these groups and at that point every one loses. I feel that every person has the capability to be able to positively contribute to a conversation. But some people lack the common respect toward others to do this on a regular basis.

CHRIS

"Michael Baglio @nc.rr.com>" On 19 Apr 2004 09:26:02 GMT, snipped-for-privacy@aol.comnotforme (Charlie Self)

Reply to
Chris Melanson

Hey Bob,

Look this is a very simple miter. 5 sides x 2 miters = 10 cuts. 360/10 = 36 degrees. Easy.

I do picture frames and after much effort went to the local high school and had the Trig teacher help me with a formula that gives me the angle for any frame of any number of sides and given the diameter of the frame will tell me how long to cut each leg.

Now the trick will be to get exactly 36 degrees. Not 35.5 because the slight difference will show. Trial and error.

Bill in New Mexico

Reply to
Bill

Geez... I think rigor mortis has set in on this dead horse. Think it is time to quit kicking it?

Reply to
Leon

Hey, Guys,

It's really amazing how long this thread continued without degenerating into the "You're a ...", "No, I'm not, you are." contest. Why don't we make an effort to keep it civil until the thread dies a natural death.

And, no, I'm not trying to be a net nanny or stifle anyone's freedom of expression, but if we were all to imagine the person being addressed is actually sitting there in person ...

Tom Veatch Wichita, KS USA

Reply to
Tom Veatch

Since you don't know how many times you stated that, I'll be happy to tell you: once. The rest of the time, you were busy insisting that the angle of the cut was 36 degrees, which it manifestly is not.

Perhaps he's referring to this post of yours on 18 Apr:

Ok you go ahead and build it that way and see what you end up with. I will guarantee you do not end up with a pentagon at all not even a square. Use some common sense if you use 45 degrees to get a square how the hell do you come up with 108 degrees?? 108 dose not even divide into 360 evenly you end up with

3.333333333333333333333333333333333 and so on show me a 3.33333333333333333 sided object through the rose coloured glasses you wear. and I will sell you the patent to widgets ok

You mean like when you wrote this?

By the way what is your occupation??? I will bet you are not a cabinetmaker.

Chris, perhaps you should go back through the thread in Google and examine your tone in nearly all of your posts. Michael said it very well: you've been making an ass of yourself with all the bravado of one whose ignorance has convinced him he's right.

-- 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

Actually there was only once I had typed 36 degree angle instead of miter which was a mistake on my part I will admit. But if you check the thread I quoted MITER at least 10 times. I had also agreed that you would achieve a 54 degree angle. At no time did I resort to personal name calling either. I had asked the question about the occupation as a point of reference to show that if you do not work in the trade you might not understand that there is a distinct difference when you reefer to something as a MITER or as a ANGLE. Example : If I asked for a 90 degree angle I would expect to see one piece of material joined to the other at 90 degrees from each other (typically a butt joint) But if I asked for a 90 degree MITER I would expect to see two pieces of material joined together with a 45 degree MITER on each piece.

CHRIS

"Doug Miller" wrote in message news:gIFhc.38$ snipped-for-privacy@newssvr28.news.prodigy.com...

wrote:

3.33333333333333333

cabinetmaker.

Reply to
Chris Melanson

Without making it clear that you were referring to the setting of the miter gauge.

Yes, you did: once.

By your email address it appears that you do work in the trade -- and by your confused syntax and garbled terminology it appears that you don't understand that "distinct difference" too well yourself.

See what I mean about garbled terminology? You're using the word "MITER" in two different senses within the same sentence.

At this point, it's perfectly clear that you do in fact understand how to set your miter gauge properly to make the cuts that you need. But it's equally clear that you do a piss-poor job of explaining it, and the harder you try to explain, the worse you do at it. It's time to quit.

-- 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

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