If you want full-sided parallel heels on the graver, rather than the short-sided traditional triangle heel, you will need to rotate the graver over more than the 52.5 degree side shape angle. Attached is a PDF showing required rotation angles for vee gravers in 5 degree increments from 60 to 130 degrees vee angle and 45-50 degree face angles
Attachments
CLAPP Graver Rotation Calculations For Creating Parallel Heels.pdf