Machining inside of curved surface normal to surface

[swimleft]

Hello, 

I am playing around with a part to learn 4 or 5 axis machining. Below is a picture of the part. In my mind, I want to cut the inside surface by doing something that looks like a parallel tool path, but which keeps the tool normal to the inside surface of the part.  

I can get what I want on the outside of the part:

I cannot get what I want on the inside of the part. I believe that the tool path looks like it does, because the surface is across the rotational axis from the direction the tool is approaching from.

Can some one point me to a good resource for takling machining the side surface of this part?

Thanks,

Eric

[seth.madore · Accepted solution]

So playing with this some, we can force different results by setting our rotation point in different locations:

 The above image is with the centerline set here:

 

 

[swimleft]

I did play around with this option a bit.

In my mind, it seemed like this would cause problems at the machine? Does the rotation center not need to be the actual rotation center of the axis?

[seth.madore]

No, I don't believe so. It WOULD if you changed your WCS origin, but this is just applying a toolpath from an imaginary projected point. 

[swimleft]

Excellent. I'm gona try and play around on some parts and report back.

Thanks.

[swimleft]

This seems to work for me. I think the angle limits flip from what it seems they would mean when the rotary surface is on the inside of a part (i.e. far side of rotary axis origin)

Thank you.