This may or may not be an easier way for you to at least learn how to make collectors. From reading some of the DIY's on here and mainly trial and error I came up with an easy way for myself to cut collectors, and maybe for some of you too.

Say you're making a 4 to 1 Collector, and you want it to be in the shape of a perfect circle, what you would optimally want is 4 different pieces with 270 degrees cut out of it (leaving only 90 degrees, so when they all butt up they make 360 degrees). An easy way to do this is simple, put your piece in your bandsaw, or in your chop saw and start by making a straight cut (in the middle of the pipe at whatever angle you desire). Once you've made that first cut down the middle, or however, what your going to do is rotate the pipe 90 degrees and cut it again (it's important to make sure that you cut the exact same length as last time, and cut the opposite way so your cuts will be like an X. (when looking at your piece after rotating it 90 degrees and preparing it for the second cut make sure you're cutting out everything except for the 90 degrees (it confused me at first too).


Now the same theory applies for a 3 to 1 collector, if you want it to be in the shape of a perfect circle then you'd optimally want three pieces with 240 degrees cut out of the pipe leaving only 120 degrees. so start your cut in the middle at whatever angle you desire, then once you've cut it, rotate it 120 degrees, and cut it again in an X pattern so that you're not cutting out the 120 degrees you rotated, but the 240 degrees that are remaining.

I'm assuming that if you want to get more of a square (clove) shape out of your collector then what you would do is cut your collector so your eliminated 260 degrees (leaving 100 degrees of uncut pipe) if you're making a 4 to 1 collector. And if your making a 3 to 1 and want more of a clove shape then you'd cut say 230 degrees out of each pipe, and leave 130 degrees.

Here's an example of a 4-1 collector that was cut less aggressively with more then 90 degrees on it giving it more of a square shape. this pic is the wrong angle so you cant really tell.


Make sure you try this out on some scrap by the way

 

ahhhhh....well ahhh....the principle in which they're made isn't the part people don't get. It's simply cutting it and rotating it exactly that gets people. Your not givin up any secrets here. Anyone can cut a bad collector...it's cutting a good one that takes some effort.

Oh and practice on pvc pipe til you get it right...that's what I did....much cheaper that way.

 

I came in here to suggest PVC, but I've been beaten. Its 1/10 the price of ss, and cuts WAY easier. I've been screwing around with it as well for manifold design.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by sharkytm &raquo;</TD></TR><TR><TD CLASS="quote">I came in here to suggest PVC, but I've been beaten. Its 1/10 the price of ss, and cuts WAY easier. I've been screwing around with it as well for manifold design. </TD></TR></TABLE>

Its harder to weld together then ss though isnt it? lol

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dr.NAPIER &raquo;</TD></TR><TR><TD CLASS="quote">

Its harder to weld together then ss though isnt it? lol </TD></TR></TABLE>

Seriously. I just can't seem to get a stable arc on that stuff. I guess I need one of those robotic tigs.