# Triangle Troubles



## BJH

Hi all..I am new to this site & am currently being challenged by a simple problem..I am making a flag display case for a friend who returned from Afghanistan & I am stuck in a corner..I have cut 45 degree angles at the top of the triangle & cannot figure out what angles to cut on the lower corners..my method was to divide the 90 degee top angle in half thereby cutting the joining pieces at 45 degrees..then to cut the remaing (2) 45 degree angles in half or 22.5 degrees each..those of you following along know this will not work..help..what angle should I use on both bottom corners??


BJH


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## Big Dave

The angles need to be cut at 67.5 degrees.


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## TexasTimbers

I think a standard 3-sided flag display case will consist of the top angle being 90°, and the two bottom side angles being 45° angles. 

A properly folded flag will have one 90° and two 45° angles so measure the flag you are giving to your friend, and build the case to fit the flag using a top angle of 90° and the other two of 45°.

If you're asking about the bevel angles where the they meet I don't see why they have to be different. Dave I don't get the 67.5 thing.


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## Lefthanded

Big Dave is right on the 67 1/2 deg miter cuts ...It's all based on 360 degrees. There are a total of 6 cuts to complete the 360 on this triangle. Subtract the (2) 45deg (90) from 360 = 270 there are 4 cuts remaining..270/4 = 67 1/2 deg. With all due respect,Texastimbers math doesn't add up (180).


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## Big Dave

Here is a picture for reference.


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## TexasTimbers

lefthanded, what y'all are suggesting the OP make is an equilateral triangle. A flag case does not have 3 equal sides. Properly constructed, the bottom will be longer than the sides. If not, the flag will not fit into the case properly and will look like crapola. 

Check my math on the crude scribble below. It's the standard shape for a flag case that will house a tradtionally folded flag. The top angle is 90° (with either a butt joint or two 45° bevels) and the bottom joints are 45s with each side member having a 45° bevel to lay on the bottom member. there are plenty of other methods of joinery. I was trying to keep it simple for the OP.


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## TexasTimbers

I was trying to keep it simple for the OP. I just reread his question though and that's exactly what he was asking. He wanted the equidistant bevels and I blew right by it. :wacko:


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## Lefthanded

Texastimbers - Your method is much easier to accomplish but visible end-grain, I think, would be undesirable. However, if the base bottom were set inside and the top mitered at 90 all cuts would be 45 deg. and no end-grain would show. The 67.5 miter is not easily done, but doable ( as seen in big daves example. )


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## GeorgeC

The flag case isan isosceles triangele. ( A triangle having a 90 degree angle the the two included sides equal.)

The angles in a triangle must add to 180 degrees, no matter the size of any angle. One angle can be 178 degrees and the other two are then 1 degree. The angles that are cut do not have to be the same as the included angles in the triangle.

Texas Timbers method is the easiest way to make the box. The Picture Big Dave shows is also correct. Just more complicated angles to cut. The bottom pieces would be cut at either 22.5 degree
or 67.5 degree, depending upon where you are measuring.
George


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## Willie T

You guys are mean.:no:

How come no one is explaining to this poor guy how to cut a 67.5 on his miter saw?

BJH,
Simply make a 45 backer to place against your fence, then put your boards against that instead of the fence, and cut 22.5's on your bottom ends.


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## Handyman

Willie T said:


> You guys are mean.:no:
> 
> How come no one is explaining to this poor guy how to cut a 67.5 on his miter saw?
> 
> BJH,
> Simply make a 45 backer to place against your fence, then put your boards against that instead of the fence, and cut 22.5's on your bottom ends.


It's just numbers. 99% of all cuts can be calulated on a calulater.


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## Willie T

It's not "just numbers" if this poor guy is scratching his head trying to figure out how to get his saw to flip to 67.5 degrees.

This is kind of the reason this is a DIY site.... to help out a little with some of the tricks.

Of course............ anyone can figure the angles. But help a guy see how to facilitate the cut. :yes: :thumbsup:


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## Fbranco

Wiki article on how to build flag display cases. Deals with angles, machine set ups and finishes.

If posting links is against the rules, please delete it.


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## bzbatl

Nice one, Willie.

On another note, Willie T - you're a Sketchup FIEND.


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## woodnthings

*There are "angles" and there are saw "settings"*

I think some confusion arises when the two are not specified. Those who [posted that a triangle must contain included angles totaling 180 degree are correct.:thumbsup: They also are correct in saying the angles on each piece are 22.5 degrees. WillyT has the sketchup diagram of the miter saw and the "backer" block also correct. :thumbsup: Here's the problem, as I see it, the miter saw angle settings increase from 90 degrees to the table or 0 degrees from 90. So when the saw is angled to one side, the increments or calibration start out small...5 degrees, then 10 degrees and then 22.5 degrees., but that's from 90 not 0, although that's what the saw indicates. 0=90 On a 45 degree cut it doesn't matter since its half way between 90 and 0 degees. but on all other angles it does. That's why we need the 45 degree backer to get 22.5 degrees. 45+22.5 = 67.5 The saw won't set to 67.5 degrees, because of it's design limitation and that's not the angle of the cut, it's the saw setting, which we just said we can't do! No wonder we get confused!:yes:


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## Lefthanded

woodnthings - Well explained and the pics are perfect. Would you recommend, for safety reasons and to make this cut a little easier, to pre-cut the pieces to length and to use a scrap backer fence to prevent the piece being cut from drawing into the blade as it's being cut?


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## Willie T

Lefthanded said:


> woodnthings - Well explained and the pics are perfect. Would you recommend, for safety reasons and to make this cut a little easier, to pre-cut the pieces to length and to use a scrap backer fence to prevent the piece being cut from drawing into the blade as it's being cut?


My fault here for not covering this. When you make any "backer" piece for any saw, it should provide provisions for clamping it to either the table , or in this case, to the fence.

All you need to do is attach a thin vertical piece along the edge butted to the fence . This upright vertical can easily be clamped to the back fence so nothing will move.


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## Willie T

bzbatl said:


> Nice one, Willie.
> 
> On another note, Willie T - you're a Sketchup FIEND.


It's because SketchUp is so quick and easy. I'm pretty accomplished in AutoCAD, but I could never do a little drawing like that in A/C anywhere as quickly as I can in SU.

That's about a two minute drawing in SU.


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## woodnthings

*Thanks, Lefty*



Lefthanded said:


> woodnthings - Well explained and the pics are perfect. Would you recommend, for safety reasons and to make this cut a little easier, to pre-cut the pieces to length and to use a scrap backer fence to prevent the piece being cut from drawing into the blade as it's being cut?


You are correct, Anything you can do to prevent the blade from sliding the pieces along is good. Double sided tape, or a backer with a clamping edge both to the fence and to the workpiece because that's exactly what they wanted to do....pull along further into the blade and messing up the angle. I personally wouldn't pre cut them but I would cut this angle the 22.5, degree first, rather than the 45..since it's the more difficult. And thanks for the compliment above.:thumbsup: bill:smile:
U got a first name Lefty? Might want to post it or should we just call U Lefty?


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## Lefthanded

*Call Me Lefty*

Bobs the name but Lefty I like...

Being left handed sometimes has its draw backs in this trade! Every tool and piece of equipment is designed for righties its something I've had to contend with. From miter boxes to drill presses, on/off switches on equipment to cutting tools. I could name many more but I won't.

I hope to impart some knowledge I've gained in the past 40 yrs of working on wood projects. You can see some of the work I've had the pleasure of designing/building at: www.watkinscabinets.com

Regards, Bob (Lefty)


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## Roger S. Blacklock

You might try this.
http://eastmanpublishing.com/library/freeflagplan.htm


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