Proper tracking of the blade is crucial to accurate cutting and considerably reduces blade breakage. The first step to ensuring good tracking is to check that the two bandwheels or flywheels are co-planar. This can be done by placing a straightedge across the front of the wheels and adjusting until each wheel touches. Rotate the wheels with the blade in position and properly tensioned and check that the tracking is correct. Now install the blade guide rollers and leave a gap of about 1 mm between the back of the blade and the guide flange. The teeth of blades that have become narrow through repeated sharpening will foul the front edge of the guide rollers due to their kerf set and force the blade out of alignment. This can be remedied by cutting of a small step on the rollers' front edges to accommodate the protruding teeth. Ideally the rollers should be crowned, (see belt_and_pulley_systems ) a configuration that assists in the proper tracking of bands and belts, at the same time allowing clearance for the set of the teeth.