Generator field endwinding blocking is described. The endwinding blocking has a spacer block for radial placement between rotor endwindings. The spacer block has a spacer body with a radially inboard end, a radially outboard end, a slot extending from the outboard end towards the inboard end, and at least one transverse hole formed on an outer surface of the spacer body, extending in a perpendicular direction towards the slot. A cap covers at least a portion of the outboard end. The cap has a radially inward portion received in the slot with at least one hole aligned with the at least one traverse hole, and at least one end extending beyond a periphery of the outboard end towards an adjacent endwinding. A fastener placed in the holes of the spacer block and the radially inward portion of the cap, secures the cap with the spacer block.