I had to bend a back to back 90 with 2" IMC on a greenlee electric bender, today. I made the first bend and marked the conduit at the back of the next bend. When I lined that mark with the mark on the bender, my bend was 3" short. Anyone know what went wrong??? That is how my ugly book shows using a hand bender. What is the correct way?
Obviousley I came up 3" short, but it wasn't a mis-measure. And yes I was measuring outside to outside. I also did rotate pipe 180 degrees. And, I made my first bend from the end of the shoe and second bend from the only notch in the shoe on this bender. That is what has me confused. There were 4 of us on this job and all confused about why this didn't work. We bend pipe almost everyday, but not usually 2" IMC. Most of what we do is 1 1/4" or less.
No, I did not figure in shrink. I used the formula from the "Ugly" book that is used for hand benders. I have not been able to find any other formulas for electric benders. Anyone know where to get bending formulas for this application?
"In cases like this, the bender should be reversed and the bend made a w a y from the first bend [ flipping the conduit around 180 degrees, Ed ] as shown in Fig. 12. Instead of using the star-point symbol, use the arrow at the mouth of the bender and allow for the appropriate take-up as though making a simple 24" long stub-up bend."
In this particular example, the goal was back to back nineties snuck into a 24" space. First a stub was bent. Then, using its projected back-side dimension, a mark could be set, coming back the other way, measured as if a stub of 24" was desired.
For non-manual benders, this should be the standard routine.