Fan Shaft Braking Device

[coss]

This design involves adding Differential Holdback Band Brakes on 4" Steel SAE 1040 Shafts in which three high-strength A490 bolts will be used to attach a 3/4" thick, 8" Diameter steel plate to the non-drive side of the shafts instead of a coupling because only about 1/4" of shaft emerges from the bearing. An 8" Shaft extension with keyway will be welded to an identical steel plate in the Machine Shop, and will then be bolted to the other plate at the site. Band Brake gets mounted on Plate and keyed to the Shaft Extension. All bolts will be "Loctite in place". The question is will tapping and threading 1 1/4" long and 1/2" Diameter holes into a 4" Steel Shaft causes cracks to form and propagate into the shaft over time at the location of the bearing or will the shaft experience an unacceptable rise in stress from the drill and tap?
Thanks!
Coss