Hi Guys

We have purchased a pipe bender (pyramid style) which has two driven rollers and a central non driven roller which clamps down onto the work.

The machine is home made but well constructed. The work we will be needing the machine for is very different from what the previous owner was using it for. The purpose we need the machine for is to coil pipe ranging from 20mm Nominal bore up to 40mm nominal bore. We tried to coil some pipe on rollers with a groove that was 1.1mm bigger than the pipe O.D. As we got closer to the diameter we wanted to coil the pipe at (275mm diameter on 26.9mmO.D x 2.6mmW.T pipe) the pipe began to slip on the rollers. Obviously there was only gripping on the very top and bottom of the pipe as the rollers were slightly too big.

My question is;
- Should the groove in the roller be exactly the same as the pipe diameter we are bending, or slightly bigger /smaller?

- Should the two driven rollers be a bigger diameter (to achieve more grip on the pipe) than the non driven roller?

- Another thing we noticed is that the central non driven roller is offset slightly closer to one of the two driven rollers, does that make it easier to bend in one direction or is it a flaw in the construction?