A guy just has to be careful doing that. I have had second growth redwood, that were grown together in a big cluster, where I had to use that method to fall them...bore through and fan out to get both sides of the holding wood...and was quick to get out. Basically the tree was fell from the undercut. I'm sure osha would not approve, but they probably would not have approved of many of my methods...but they worked for me 



