It’s a Woodland Mills WC-68.
https://woodlandmills.com/wc68-6-pto-wood-chipper/. I co-own it with my brother. It doesn’t have an hour meter so hours on it is a swag, but I’ve probably put 150 hours on it. My brother has probably put another 50 on it for a total of around 200 hours.
So far, I’ve touched up the reversible blades with a diamond hone, but I haven’t needed to turn them around or have them professionally sharpened yet. Set the bed plate gap after. May not have been necessary. That was a bit of a trick being the gap you’re measuring is at the bottom of the flywheel housing, but not too difficult after planing out a board to the right thickness to act as an unusually long feeler gauge.
Replaced the rear pillow block bearing on the flywheel because I very stupidly pulled the wrong lever of the three to the right of the seat without looking, which pulled the hydraulic toplink on the tractor all the way in, bottomed out the PTO shaft, and thankfully busted the housing for the chipper bearing rather than busting the tractor’s PTO. Called Woodland Mills and had a replacement bearing in less than a week for less than I could buy the bearing from Grainger or McMaster Carr (it’s a pretty generic pillow block bearing).
PTO hp on my HST L4701 is listed in the manual at 37.8. Woodland Mills specs the chipper for 20 to 50 hp and 6” maximum material size. IME on my L, it will chip anything that fits in it, despite having only 37.8 hp. I do not run dirty/sandy wood through it or wood that may have imbedded metal (such as old wooden fence posts). The blades have to be paper slicing sharp to work correctly,
My only prior significant experience with a chipper was one I used long ago when I worked for a tree service for a couple years back in the late 80’s. That one was a 110hp Eager Beaver hydraulic feed with two infeed rollers and 12” capacity. The WC-68 has only one infeed roller, but I’ve found feeding the WC-68 to be very much the same as the old Eager Beaver. There’s a little bit of technique to getting a large thing started but it’s not difficult to figure out. Stand on the left side when feeding because if it kicks when the branch hits the flywheel, it kicks to the right. To avoid plugging the chip chute, slow the feed rate for sticky green stuff like fresh pine. If chipping a long hardwood limb near full capacity, if the engine starts losing RPM, pause the infeed to let it catch up and go at it again before it lugs down much.
Don’t have any regrets. Because I’d spent a fair amount of hours with a larger hydraulic fed chipper, I had some expectations. None of the “issues” or “tricks” mentioned above is any different than running the big commercial unit from the 80’s. It has met my expectations and has not disappointed me.