First of all , Stumper is right on the money with the "inch-pound" instead of "ft/lbs" setting!!!
Secondly, Plyscamps is right about the cutter-wheel shaft being soft/worn in the bearing area....
As far as thats concerned,here's what I did to cure the problem of new bearings "knocking"
The knocking occurs because of wear on the shaft and because of the slip-fit tolerance between the bearing bore and the shaft diameter. There's a few thousandths clearance , which allows you to slip the bearing on easily.But, when you tighten down the lock-collar ,it cocks the bearing bore at a very slight angle.. Coupled with the inevitable wear on the shaft from the previous bearings ,the tolerance is greater resulting in a "knock sound. About the third time you replace bearings, the wear will be greater, usually resulting in having to replace a very expensive cutter shaft.
After replacing two shafts, I took a worn shaft to a certified welder and had the bearing surface area built up with a hard-face rod.
Then ,I took a new bearing and the shaft to a precision machine shop and had the shaft turned down to a press-fit O.D. I also had the shop to machine flats for the bearing set screws to seat on..I pressed on new bearings and installed the assembly. This cured the knocking problem .Not only curing the knocking, the bearings lasted much,much longer.. I had this done in mid-season 2011 and it has lasted since then, with the bearings just now starting to make a slight noise. I have just taken a spare ,worn shaft to the welder to get it done for the 2013 season....
Stan
