# 30° miter, how to find bevel angle to mate?



## Ralph032581 (Feb 12, 2014)

Hi,

I am building a bird feeder and used two 30° miter cuts on the top that meet like a triangle. I thought a 30° bevel cut would work for a roof... however it did not. I attached a very rough sketch.

How do I find the angle to make my two bevel cut to fit the miter cuts?

Thanks for your help.


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## Miller Woodworks (Dec 11, 2013)

For the top point to be 30°, you'll have to cut the two pieces that join together up there at half of 30°, which obviously is 15°.

It's just like making a square corner. For that you miter at 45° and put two 45s together to make the 90° angle. The only difference is that you want 30° total instead of 90°.


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## JohnK007 (Nov 14, 2009)

Yep, Miller is right on. Not much to offer other than to say don't feel bad, I've scratched my head a few times too when I forgot to divide by 2. It happens and your question is a great reminder to everyone. Thanks and good luck with your project. There will be some happy birds in your area soon!


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## Ralph032581 (Feb 12, 2014)

Thanks, Guys. Have a great day!


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## whiskeypete (Jan 23, 2013)

Miller Woodworks said:


> For the top point to be 30°, you'll have to cut the two pieces that join together up there at half of 30°, which obviously is 15°.
> 
> It's just like making a square corner. For that you miter at 45° and put two 45s together to make the 90° angle. The only difference is that you want 30° total instead of 90°.


Its 90 minus half the angle you want

A normal straight cut has a bevel of 0 degrees. If you want to make the angle between the two roofs to be 30 degrees, 90-15 = 75 degree bevel. Thats a steeply pitched roof though


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## Billy De (Jul 19, 2009)

Not busting anyone's chops on this but in geometry there are some thing that always stay the same no matter what. One of them is that the angles in a triangle always add up to 180 degrees that's a given it never changes.

So go back to the drawing you made in you first post and draw a line from the top of the roof straight down then draw a line from the top of the wall by the edge of the roof on one side to the top of the wall and the edge of the roof on the other side, so now these two lines bisect each other. 

We now have two triangles in other words the front of the roof and the back of the roof.Where the two lines bisect each other we know that this angle is 90 degrees, it will always be 90 degrees.

In your first post you say you want an angle of 30 degrees this is called the pitch of the roof and we write it in the right hand corner of the roof,so now we add 90 +30= 120, the total angels in a triangle= 180 so 180 - 120 =60,the top cut will be 60 degrees.

The top cut is called the plumb cut and the cut on the right hand side is called the seat cut. so we know that the plumb cut and the seat cut will always = 90, answer :- the angle you are looking for is 60 degrees, have fun and enjoy it Billy.


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## tc65 (Jan 9, 2012)

Here's a quick and dirty drawing to illustrate Billy's post.


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## Miller Woodworks (Dec 11, 2013)

Oh, I thought you wanted a taller roof with the 30 degrees at the top angle to keep squirrels from eating from the bird feeder. If you wanted the shallower roof like a normal house, you need 60 degrees on the top as Billy said.


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## whiskeypete (Jan 23, 2013)

The OP is asking how to find what bevel cut to use. To make the roof described by billy (30 degree pitch) the bevel cut at the peak would be 30 degrees. Look at your miter saws. The 60 angle is right geometrically but that is not the bevel.


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## Billy De (Jul 19, 2009)

Miller Woodworks said:


> Oh, I thought you wanted a taller roof with the 30 degrees at the top angle to keep squirrels from eating from the bird feeder. If you wanted the shallower roof like a normal house, you need 60 degrees on the top as Billy said.


I can see what you talking about,but when I saw the 30 degree I just took it automatically to mean pitch.


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## woodnthings (Jan 24, 2009)

*The angle in the sketch is 60 degrees, not 30*

It's labeled 30 degrees from the vertical, which is 60 degrees from the horizontal. This is why the "pitch" is so steep. The angle needed for the miter to mate to the roof, however is 30 degrees on each piece. Unless I'm missing somethin' .... :blink:


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## Al B Thayer (Dec 10, 2011)

Ralph032581 said:


> Thanks, Guys. Have a great day!


Oh your not done yet. this thread will play out for days. 

Al

Nails only hold themselves.


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## woodnthings (Jan 24, 2009)

*He's gone...*



Ralph032581 said:


> Thanks, Guys. Have a great day!


But we're not done here. :no: :laughing:


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## tc65 (Jan 9, 2012)

Ralph032581 said:


> Hi,
> 
> I am building a bird feeder and used two 30° miter cuts on the top that meet like a triangle. *I thought a 30° bevel cut would work for a roof... however it did not.* I attached a very rough sketch.





woodnthings said:


> It's labeled 30 degrees from the vertical, which is 60 degrees from the horizontal. This is why the "pitch" is so steep. The angle needed for the miter to mate to the roof, however is 30 degrees on each piece. Unless I'm missing somethin' .... :blink:


I think we are all making assumptions. The sketch shows a steep angle, but that could just be the sketch... Several assumed 30 degrees from horizontal, woodnthings assumed 30 degrees from the vertical (I'm assuming based on the steep angle of the sketch).:laughing::laughing:

In fact, absent clarification from the OP - we are both correct.

AKA - Shrodinger's Cat. http://en.wikipedia.org/wiki/Schrödinger's_cat :yes:


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## Al B Thayer (Dec 10, 2011)

I'm going for the popcorn.

Al

Nails only hold themselves.


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## woodnthings (Jan 24, 2009)

*Ralph, Come on back over here!*

Popcorn is on, sides have been taken, assumptions made, bets are being wagered, and you are where? :boat::scooter::wheelchair::tank:


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## tc65 (Jan 9, 2012)

Don't worry, he'll be back - 

- especially if he hasn't read any posts since his last post and goes ahead and makes some 15 degree cuts. Now that would be a steep roof! But it still wouldn't be enough to keep the squirrels off it.


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## Trav (May 30, 2011)

woodnthings said:


> Popcorn is on, sides have been taken, assumptions made, bets are being wagered, and you are where? :boat::scooter::wheelchair::tank:


This is why I read this forum everyday!


Love it!


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## tallmike96 (Jan 3, 2014)

You guys are awesome seriously....


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## del schisler (Nov 5, 2009)

*angles ??*

where else can you get this kind of intertainment , enjoy


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## cabinetman (Jul 5, 2007)

This should have really been done like a poll. Good thing it wasn't asked how many degrees are in a straight line. 









 







.


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## Trav (May 30, 2011)

I keep setting my chopsaw on 30° but it cuts the wrong angle.


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## mdntrdr (Dec 22, 2009)

....:huh:


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## TimPa (Jan 27, 2010)

Ttharp said:


> I keep setting my chopsaw on 30° but it cuts the wrong angle.


maybe it needs adjusted!!!


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## Ralph032581 (Feb 12, 2014)

*Pictures of item attached... 60° will get it??*

Thanks for all the great information! 

Here are some pictures of it, so 60° bevel cuts will get a full roof?

Thanks again.


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## whiskeypete (Jan 23, 2013)

If you measure bevels like this, its 30 degrees


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