bending exhaust pipe....kinda

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Can anyone give me some info or a site that gives info on cutting straight pipe and welding it together to create a bend?  Are there formulas or anything to go by? Thanks in advance
Reply:Well depends on how many sections you want to make the bend in and degree ex . Youu want a 90° and you want to do it in 3 sections you divide 90 by 3 gives you 30°  on both side of the sectionsLincoln Power Arc 4000 Thermal Arc Fabricator 252 iThermal arc 186Thermal Arc 26 tigTweeko 200 amp spool gunHobart AirForce 400WP-17V-12R
Reply:Thanks,  that seems simple enough. How would I determine the radius of the bend? And is there a name for this particular process?
Reply:The radius of the "bend" is dependant on how far you space your cuts apart.Smallest "bend" is with the cuts being pie shaped.Dave J.Dave J.Beware of false knowledge; it is more dangerous than ignorance. ~George Bernard Shaw~ Syncro 350Invertec v250-sThermal Arc 161 and 300MM210DialarcTried being normal once, didn't take....I think it was a Tuesday.
Reply:I get that much but I was just wondering if there is a formula so it's not so much a guess and check method.  Say 1" gap in the inner part if the radius would equal a 7" radius etc.
Reply:Originally Posted by SactoWeldI get that much but I was just wondering if there is a formula so it's not so much a guess and check method.
Reply:Thanks for the replies. I think the pencil and paper route is the way I'll end up going.
Reply:I've only done a couple pie cut bends in my life. What I did was just cut a bunch of random (all the same but never knew size/dimensions/degrees) and just kept welding them together till I had the bend I wanted. If the bend ended up a bit more than I wanted in the end I would just cut it to what I needed after all welded up.I soon realized pie cut bends are a waste of gas, filler, electricity, and time. I just buy pre bent 180 degree tubing now in the size I need and cut out the bends I need at the time.
Reply:Originally Posted by VPTI soon realized pie cut bends are a waste of gas, filler, electricity, and time. I just buy pre bent 180 degree tubing now in the size I need and cut out the bends I need at the time.
Reply:thanks for the info, thats good to know.  i was thinking it may save me some money on future projects but i guess i'll just stick to the mandrel bends
Reply:Originally Posted by assassin_worksWell depends on how many sections you want to make the bend in and degree ex . Youu want a 90° and you want to do it in 3 sections you divide 90 by 3 gives you 30°  on both side of the sections
Reply:Like High School Math, I got lost after the Teacher introduced himself at the top of this post!
Reply:I make my own and roll them, You can do increasing tapers that form what ever you want it to. Lot of drawing time to do this though.
Reply:Oscar--I like your illustrations. If I may make one suggestion it would be, instead of 90 degrees,  angle the ends of the straight tubes such that the weld joint bisects the angle between the straight tube and the first pie-shaped section. And to evenly divide the angular change such that the 3 small sections are identical to each other, rather than asymmetrical.
Reply:Originally Posted by ezduzit to evenly divide the angular change such that the 3 small sections are identical to each other, rather than asymmetrical.