OKay, we got a partial afternoon of chipping in, running the tractor up to 2300+ rpm, making the PTO 540 rpm. And not one clog! All just cut branches from 2 good sized Doug Fir trees, and misc. green brush. I have not checked the bed knife yet. I guess you just have to have max rpm to throw the product out the blow pipe. What do you think is easier to chip; fresh green, couple months dry, or full dry material? Thanks for the good advise ArborSiters!