Hi hog,
It's definitely not what the cutter's made for...
That being said--they'll blow a large (up to 20") rotting stump to pieces lowering slowly...
Biggest solid one was cedar, about 16"--gently (how can you say that talking about a shredder?) working into it... took about 45 seconds...
Course those were pre-existing on the "lawn",... otherwise would've pulled & filled. /forums/images/graemlins/grin.gif