Belt Grinder wheel set knife grinder 4" Drive- 5/8" shaft, 3" tracking, 2" Idler - USA Wheel Set Description: One (4") diameter Drive Wheel: Drive wheel is CNC machined with 5/8" bore (H7 tolerace). Bore is equipped with a 3/16" key way and a set screw. Wheel is (2.2") wide. Bore is (1.57") long . Surface of wheel is truly crowned to insure belt won't jump off wheel . Please refer to the wheel's sketch for the exact wheel dimensions Two (2") diameter Idler Wheels: Each wheel is CNC machined and fitted with three 1/2" bearings. (Heavy duty 6201-1/2 RS bearings) Bearings are rubber sealed to protect from dust. Bearings are placed back to back (best combination). A 3/8" wide standoff (sleeve) will raise the wheel of the mounting plate. This bearing combination is the best tested solution against bearing failure as it allow for tightening The mounting bolts without causing any axial force on the bearings (ball bearings should not bear lateral load) One (3") diameter Track Wheel: Each wheel is CNC machined and fitted with three 1/2" bearings. (Heavy duty 6201-1/2 RS bearings) Bearings are rubber sealed to protect from dust. Bearings are placed back to back (best combination). A 3/8" wide standoff (sleeve) will raise the wheel of the mounting plate. This bearing combination is the best tested solution against bearing failure as it allow for tightening The mounting bolts without causing any axial force on the bearings (ball bearings should not bear lateral load) Shipping: All orders are shipped the same day if paid by 2 PM central USA time Expedited Shipping (USPS Priority Mail)