C axis interpolation

Hello, I need a little help, I've been working with a Haas St-40 Z,X and C axis at the manual and at the factory they still have no answer for it. I am trying to open a diameter on the side of a tubing, having hard time getting the machine to work Z and C axis, is anyone can sent me a sample program how that can be done. Z0 is the center of the dia. There is no Y axis
(*ROUND POCKET 1.0DIA.)
T101 (*3/8 4FL ENDMILL*)
G56 (* FIXTURE OFFSET *)
M154 (ENGAGE C AXYS)
G00 G98 Z3.
G97 M133 P1000
(M133 LIVE TOOLING DRIVE FORWARD)
G00 X11.
G00 Z1.
M08(* COOLANT ON *)
G00 Z0.2 C0.
G01 Z0 F50.
G01 X10.3
G01 X10. F2.
**** this is the section
G01 C-3.586 F1.(* diamante shape, need to be a diameter about 1.0 inch)
Z-0.3125 C0.
Z0 C3.586
Z0.3125 C0.
Z0 C-3.586
*****
G01 C0.
G01 X11. F50.
G00 Z0.1
G00 Z3.
G18 (* PLANE SELECTION *)
M09 (* COOLANT STOP *)
M135 (*LIVE TOOL DRIVE STOP*)
M155 (*C-AXYS DISENGAGE*)
G00 G59 X0 Z0
M30

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Thank you