Cuttin down rods

[Crow]

It takes a bit more time , but I've had success with a mini-triangular file. It leaves a nice clean cut. I'm sure there are more high tech solutions but this works well.

[Nebe]

the bigger the tooth, the more chance you have of tearing your blank and causing damage IMO....

i've never done it though-

[Saltheart]

I like a little cut off wheel on a dremel. Rotate the rod on the lathe and hold the tool still and just feed it in a little at a time.

My second choice would be a fine metal file.