Robertson Screwdriver

Robertson or Square Recess, #0, #1, #2, #3 SCREWDRIVER BIT screw head and does not slip as easily as the slot Additionally, it

One thing The History Guy left out is that practitioners of a brand new industry preferred Robertson screws

slot big77 Interestingly, although they were always sold at a premium price, it is actually easier to make Robertson screws than slots screws, as slots involve a punch for

slot machine wild crystal arrows ROBERTSON SCREW APPLICATION FILED OCT 24, 1907 Patentd Nov 8; 1910 ' UNITED STATES PATENT OFFICE