I’m seeing a lot of people here claiming that the Philips head was originally designed to cam out/strip to prevent a transfer of force sufficient to twist the head off. While I agree this does sound logically plausible, I could find no reference to such features in the original patent: https://patentimages.storage.googleapis.com/0f/28/e3/3e3075abbb9779/US2046837.pdf 🤷♂️
Yup. “Cam action” is only mentioned in the context of the wedge shaped driver/bit squishing out any crud that had lodged itself in the screw. The entire idea was self-centering and better engagement between the driver and screw due to the wedging. The fact that it failed more gracefully is a side benefit at most, and more likely just sales fluff to compete against Robertson.
To be fair, I have snapped a few Robertson in my day, certainly higher by percent than the number of Phillips I’ve used, but that’s more than balanced out by the huge number of crappy Phillips heads that have been almost as totally ruined by camming out under fairly normal use with a properly fitted driver.
I’m seeing a lot of people here claiming that the Philips head was originally designed to cam out/strip to prevent a transfer of force sufficient to twist the head off. While I agree this does sound logically plausible, I could find no reference to such features in the original patent: https://patentimages.storage.googleapis.com/0f/28/e3/3e3075abbb9779/US2046837.pdf 🤷♂️
Yup. “Cam action” is only mentioned in the context of the wedge shaped driver/bit squishing out any crud that had lodged itself in the screw. The entire idea was self-centering and better engagement between the driver and screw due to the wedging. The fact that it failed more gracefully is a side benefit at most, and more likely just sales fluff to compete against Robertson.
To be fair, I have snapped a few Robertson in my day, certainly higher by percent than the number of Phillips I’ve used, but that’s more than balanced out by the huge number of crappy Phillips heads that have been almost as totally ruined by camming out under fairly normal use with a properly fitted driver.