There are a number of things that can cause problems when bending 3" pipe. This size has become popular in the last 10-12 year. Most of the manufacturers of pipe benders struggled with getting this corrected in the beginning. With that in mind, let me list a few things that I have learned in my experience in dealing with this problem. First, and perhaps foremost, the pipe must be of the correct thickness to be able to maintain the integrity of the wall of the pipe throughout the bend. A minimum of 14 gauge is required to be able to bend with no collapsing or crinkling. One bender manufacturer recommends 13 gauge tubing. There is one thing to keep in mind. Gauges of pipe is measured in a range, not a specific thickness. 14 gauge steel has a range of approximately .70 - .79. If a tubing manufacturer gets on the low end of 14 gauge, bending problems can occur. If it maintains thickness close to .78 or more, problems are seldom seen, providing the bender is in good shape. (We will discuss bender problems in a bit.) Remember, steel is bought in price per pound, so a manufacturer can save money by staying on the low end of the gauge range. Next, a very important factor in bending 3" pipe is to make sure that the pressure on the back gates of your pipe bender is set to the proper pressure. Pressure that is too low will cause "sucking in" on the backside of the pipe. If it is too high, you are working against the main pressure of the machine and making it almost impossible to bend the pipe. In general, follow the manufacturers recommended setting and you should be fine. I know that the pressure for the Huth family of benders is 800 psi. (If your gauge is broke, get it replaced.) The Ben Pearson is also set at 800 psi, and Ben Pak is 1000 psi. Third, on benders that have adjustments, make sure that the adjustments are made to give you optimum bends. The Huth and Bendpak benders have no alignment adjustments that need to be made. The Ben Pearson and Worth benders have adjustments that can be made. Please refer to you operators manual. (At a later date, we will be putting detailed instructions on adjusting those benders to optimum settings.) Fourth, make sure that you do not have dirt, grease, and trash built up on the back gates where the back shoes sit. The dies must sit flat on the back gates, and if something is holding them away from sitting flat, this can cause bending problems. Also, you do not want buildup of dirt and grease on the dies. We recommend lubrication, but on the dies it should be something like WD-40 that lubes, but does not build up. Finally, if you have had your 3" dies for a number of years, and have used them a lot, you may simply have dies that are worn out and need to be replaced. On a number of occasions, I have taken new dies into a shop and was able to determine through comparison, that a customers dies were worn out. I trust this might have given you some suggestions on what to look for if you are experiencing problems bending 3" pipe. I know that it is frustrating to have a job sold and not be able to complete it due to this problem, or to have to turn down a job for this reason.
