can someone tell me where to find the info out on learning to pie cut? i have to build my down pipe and i have right at 3in from the turbo to the a/c compressor and i need to make a sharp bend.. anyone have any ideas?

 

It's just a matter of taking a straight piece of tubing and cutting it at a certain degree. You can make it as tight or as loose as you want. 7.5 degree cuts will equal 15 degree sections and that will take 6 pieces to make a 90 and etc..

 

so u make a 7.5 degree cut then spin the pipe around and make another 7.5 degree cut to make A pie? and keep going back and forth like that?

 

exactly, spin the pipe 180* after first cut and rinse/repeat

 

exactly

 

ok how big should the smaller side of the pie be? or does it depend on how much bend u need?

 

I usually go about a 1/4" on the small end. Seems to get into most tight spots.

 

thanks man.. uve been a great help.. i should be able to get it now.. i played around yesterday for a few hrs and got it close.. but i was just guessing.. ive built dp's and charge piping before using u-bends but never needed to make a tight bend like this before..

 

search "pie cut calculator" on google and find the first reply with an attached spread sheet. you will need something that can view xls excel files.


the calculator will let you choose your center line, and amount of pieces required.


for 3" i usually go with a 3" center line, and 4 pieces per 90. that way u can use only 2 22.5deg pieces to make a 45 if required.

it winds up being 11.25 degrees on the bandsaw and 1.75" long on the long side of the cut. remember, each pie piece has two angles, so 11.25+11.25 = 22.5 degrees total.

 

thats a really sharp angle!

 

Here is an example of a job I did that required it. I went with alot more pieces, for a smoother look.
I also stick around 1/4-3/8" on the small end.
I take a piece of angle iron, and mark straight down the tube. Then, measure the circumference with a sewing tape, and divide in 2. Mark this from your straight line in a few places, then draw a 2nd line with the angle iron on those marks. Those lines are now 180 apart, and make it easy to get your measurements right as you turn back and forth.

You can see the lines I marked on the aluminum test piece. They act as terrific line-up marks for getting a 90 without twist if that is what you need.
I'll try to snap a few pics as I have to do this again in a similar fashion on a 2011 vert camaro with a blower and custom hood.

 

Like everyone stated . straight line on each side of the pipe cut flip 180 cut again. Ive done 1/16"-1/8" on the small side to get in some tight areas and it can be a PITA welding them due to the lack of material.

Nice work 9Bells

 

buy them!!

http://www.maperformance.com/maperfo...-map-fab1.html

 

**** that is cheap for that.

 

I know thats why i posted it///

 

Good info in here! Did a little work with some tight radius stainless today following tips posted.

Here's the part with cheated bends on tight CLRs


and with pie cuts

 

http://www.motokarts.com/resources/p...calculator.xls

 

i spy a gti-r motor

 

10 degree pieces. Made these for a friend. Pie cut the dump just to make it match the dp.

These sure take a lot of time. Mandrel bends take I bet an 1/8 of the time.

I mainly do these for the practice. It can really help your consistency with the lighter gauge stuff.

 

check out the pipefitters blue book it will give you all sorts of methods for calculating stuff that pipefitters use that you can use when fabbing up stuff.

 

wish i could cut something that smoothly..best I have is a reciprocating saw and that stainless destroys a blade after about three cuts

 

A porta-ban is fairly cheap. A couple hundred dollars for a nice one. You can cut straight cuts easily with it.

 

I use a chop aw and love it.

Beautiful pie cuts. Never thought id say that

 

You don't square off the pipe after each cut?

 

great info on here