How to cut a continuous channel on the inner surface of a hollow cylinder? 1

[shidinghao]

I wanted to create a continuous channel on the inner surface of a hollow cylinder, like pic 1. The channel can be treated as a pattern repeating itself. I tried to create a sketch then extrude cut, then pattern it, it doesn't work well since the continuity of the pattern, it's hard to have the end meet the start, and there are always corners that remain uncut, you can see it from pic 2.I was wondering if there is a good way to do that?

Any constructive suggestions are welcome. Thanks very much!

 

[JohnRBaker]

Can you provide at least a picture of what you're trying to model?

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Digital Factory
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[mmauldin]

I'm not sure of all your requirements, but attached is a file showing a couple of ways to make the channel. You can turn off the Offset Region and turn on the Thicken and Subtract to get either a channel or split the body fully.