NO, not even once, the jack is set in the tree, it's not going anyplace when you are cutting........UNLESS, you stay under it and watch the tree fall....if you are that stupid, then maybe a knock on the head, will knock some sense into you... lol
To those nay-sayers, (not you gaproperty)
I could go on about how well it's designed and works, and how much better it is to have a crank over a jack ect... But, I guess i'll let those that have NEVER used or even seen one in the flesh, tell how dangerous it is and how they could design it better ect. ect...
SR