Question about tube bending

[Tuomas]

I am wondering if there is an ideal distance between the main die and the roller die for a tube bender of this type.

i currently use a Bramley manual tube bender, and notice if I put the roller cam too close, the tube will crimp when bending.

It seems there would be an ideal distance based on tube diameter and bending radius, but cannot find anything anywhere on the best placement distance for this roller. Perhaps it does not matter, as long as it is not too close?

any ideas on how to calculate optimal location for roller cam for this type of long arm tube bender would be appreciated.

cheers

Can i ask. Where did you get that picture?

Distance doesn't matter. But, i can measure it later.
It would have been better to make the question to its original thread, i think.. Homemade manual square tube bender

Edit: in that bender. Distance is 2 * radius of the die + tube width + 10mm clearance. ( 50mm radius and 25* 25 square tube, =135mm