My question is How do you fit the oval header flange to the round piping? and how do you keep the header flange from warping while welding?

 

Just weld the pipe up and then grind out the obstructions. Bolt the flange to a spare head for welding, or tack weld it and go an inch at a time in opposite spots to let it cool slightly before working on that area again.

 

first you make a jig and ovalize the round tubinh to the correct size.
second you get a piece of 1/2" plate and bolt the flange up to it then weld away but first tack all the tubes in 3-4 spots.

 

Ive never built a mani. before but when I get around to Im going to put the bends in a vise and smash them to try and ovel the ends out so they fit the flange.Now thats seems like it would work in theory but Ive been aching to try it.

as far as welding it so it wont warp,if you dont have a spare head just get a scrap piece of flaat stock drill holes in it and bolt the flange to it.

 

thanks for the help guys and i can see what your talking about now stealthmode thanks

 

i oval the pipes in a vise.

and i use a 1/2 plate to bolt manis to while i weld.

on logs, if your good enough with the saw, you dont need to oval them.

boo yah ------

 

1/2" isn't thick enough. i bolt mine to a 2" thick plate i drilled and tapped the holes into. every hole gets bolted to the plate to ensure flatness. i don't take it off until i can do so without wearing gloves.

 

1/2 inch works for me.,

 

I have to agree with aaron, thicker is better. A simple Vise, has to be fairly strong will oval the pipe no problem. Just make sure you keep retorquing the bolts on the jig as you weld.

 

what would be so bad about just bolting it to the head you will be using?