Shortening copper pipe

[ml1337]

I'm a DIY'er, beginner in plumbing. Is there a trick to cutting a very short amount of copper pipe, in order to line up a fitting? Whenever I try to cut say 1/16, I can't seem to keep the cutting tool at that exact location, and it ends up shifting further in as I make turns around the pipe...

 

[Reach4]

Grinder or file?

 

[Sponsor]

 

[Terry]

I wouldn't even try to cut off that little amount.