Formula for making precise PIE CUT BENDS............!!!! - HomemadeTurbo - DIY Turbo Forum
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Old 05-27-2007, 04:47 AM   #1
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Default Formula for making precise PIE CUT BENDS............!!!!

To make precise pie cuts bends I have provided a nice simple formula.
This formula makes a bend that is whatever angle you desire.



CLR = Center Line Radius (radius of the bend measured through the center of the tubing)
D = Diameter of Tube _____
L = Length of long side of pie cut - the top of this pie cut -> \____/
Angle = angle to cut pie section which, this angle is measured perpendicular to the length of the tubing
Bend Angle = The angle of the bend
N = number of pie sections to complete bend
* means multiply



L = [ ( 2 * CLR ) + D ] * [ sin ( Angle ) ]

Angle = Bend Angle / ( 2 * N )




Example:

You want to make a bend that is 120 degrees, uses 3" diameter tubing with a CLR of 4", and 5 pie sections.

Angle = Bend Angle / ( 2 * N )
Angle = 120 / ( 2 * 5 )
Angle = 12

L = [ ( 2 * CLR ) + D ] * [ sin ( Angle ) ]
L = [ ( 2 * 4" ) + 3" ] * [ sin ( 12 ) ]
L = [ 8" + 3" ] * [ sin ( 12 ) ]
L = [ 11" ] * [ sin ( 12 ) ]
L = [ 11" ] * [ sin ( 12 ) ]
L = [ 11" ] * [ 0.208 ]
L = 2.288"

[size=16pt]L = 2.288"
Angle = 12 degrees
_____
Now you need to cut 5 of these -> \____/ with the top part measuring 2.288" in length.




Here is an Excel ------sheet that t_cel_t created that uses this formula for you mathematically challenged individuals. Pie Cut Excel Sheet



EDIT*

Here's the downpipe and mani I did for my car. It's 3", uses 5 pieces per 90*, and has a CLR of 3"
[/size]


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Old 05-27-2007, 07:45 AM   #2
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Default Re: Formula for making precise PIE CUT BENDS............!!!!

nice! This should come in handy for me very soon when I fab some cooler piping.
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Old 05-27-2007, 09:01 AM   #3
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Default Re: Formula for making precise PIE CUT BENDS............!!!!

My formula is eyeball x pipe / radius of the imaginary pipe in my mind= close enough.
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Old 05-27-2007, 11:41 AM   #4
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Default Re: Formula for making precise PIE CUT BENDS............!!!!

Quote:
Originally Posted by CSaddict
My formula is eyeball x pipe / radius of the imaginary pipe in my mind= close enough.
x2 if it looks like it will work ill maike it fit!!
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Old 05-27-2007, 11:58 AM   #5
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Default Re: Formula for making precise PIE CUT BENDS............!!!!

Quote:
Originally Posted by CSaddict
My formula is eyeball x pipe / radius of the imaginary pipe in my mind= close enough.
Lol that's how I used to do it at first, then I smartened up. Framing square ftw, has all the angles on there. I just figure out how many bends I want to make the turn and find what angle it'll be for them with the square.
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Old 05-27-2007, 12:13 PM   #6
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Default Re: Formula for making precise PIE CUT BENDS............!!!!

Quote:
Originally Posted by CSaddict
My formula is eyeball x pipe / radius of the imaginary pipe in my mind= close enough.
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Old 05-27-2007, 12:27 PM   #7
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Default Re: Formula for making precise PIE CUT BENDS............!!!!

Quote:
Originally Posted by CSaddict
My formula is eyeball x pipe / radius of the imaginary pipe in my mind= close enough.
haha thats awsome
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Old 05-27-2007, 01:21 PM   #8
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Default Re: Formula for making precise PIE CUT BENDS............!!!!

i seen this on here before, but make it a sticky!!!!!!!!!!!!!!!!!!
thanks
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Old 05-28-2007, 09:12 PM   #9
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Default Re: Formula for making precise PIE CUT BENDS............!!!!

thank you
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Old 05-28-2007, 10:35 PM   #10
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Default Re: Formula for making precise PIE CUT BENDS............!!!!

Why would nobody care about this? It's a great bit of information, I say sticky in the Fabrication section.
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