Hello All,

I am a student and am interested in the production of a composite tubing similar to a Bowden cable:

I have steel helically wound tube with OD .312" and ID .355" . I want to apply flexible PVC casing. I have PVC with ID of .330" and 0.025" thickness.

Clearly the steel winding is too large for the PVC casing...

My guess is to apply torque to helical winding to reduce OD and then insert into PVC during extrusion, but this would cause plastic deformation. Could I inflate the PVC? I am limited to using the stocked materials and do not have access to heat shrink solutions.

I have had difficulty finding resources to help... thank you in advance!