Those chippers have actual bladed in them in that big drum looking thingie next to the engine and blades and nails don't mix...
Unless you rent a big chipper with a 4 cylunder engine ($100-$150 a day) yer probably going to get a 1 cylinder at the rental center and it will olny chip limbs up to 2" and chip them very slowly... Like 3-4 minutes chipping a 3 foot long 2" round branch...
But if yer gonna get the 4 cylinder chipper it will chip up stuff up to about 3 inches quite nicely and you don't have to push the limbs into it... Once it grabs 'um they are gone... Also with thei chipper, if you can use a circular or chain or nailpuller and get the nails out then Mr. Chipper will eat the rest of the fencing and ask for more...
Those are my thoughts... BTW, if you are looking at renting a 1 cly. chipper sgredder it gonna probably cost you about $50 for the day... If you have one of those magizines that has used stuff in it that is usually sold at the convience stores then you might find one in there used for not much more and then you could chip at your liesure...
We bought one for $200 that works great...
As for my limbs and stuff, I have a couple big fires every year but then again I've got 17 acres to keep up, 5 of which are wooded where are gardens are...