A long time ago I was directed on grinding the reels and bed knives for a golf course gang mower set, and I remember taking some of the lapping conpound for valve grinding compound --it was in between the 320 and 180 that I had, these were iron wheel mowers fron the20s, first the bed knives were ground flat across the length, then a relief, and the reels were set on a fixture and ground so the contact area was small-relief angle-then to a cylinder shape (round) a tool was installed to turn the reel backwards to lap the reel to the bed knife with compound -after they were ground--properly adjusted they took almost no effort to pull, the contact area had to pass a piece of newspaper flat without cutting it, yet when presented 90 degrees to the blade contact cut it cleanly. ---at one time I was offered the sharpening machine, the old mad had died, I was the only person that knew how to use it, but I had no place to keep it and wasn't interested in sharpening reels then.