SOMEWHERE I once read you could machine semicircular nicks on the external radius of internal stiffener rings. These are useful for running longitudinal wires or piping while keeping things protected. I think the allowable radius of these semicircles was expressed in terms of the of the stiffener diameter.
Problem is, I can't find where I read this. Does anyone have this info, or at least some rule of thumb?
thanks!
- Alec