I don't know, and was wondering that myself. I think what may happen is that you jostle a stone loose, and it might precipitate a blockage, so it may actually be more of a risk in those circumstances. Unless you just want to get the stone out, and are willing to accept that possibility.
I did it for awhile without a blockage, and my results came back from x-ray that I don't have any stones. I know I had them at one time, as I actually felt one drop inside of me. I don't know if my doing this had anything to do with it.
Realize that most stones come out on their own. Best thing is to drink lots of water. Chanca piedra may help as well. If you know more about your stone's makeup and kidney health, you can experiment with other things.