When Peter Robertson invented the Robertson Drive again this gives four points of contact or four points where a load of turning the screw is transferring over onto the screw head so in this case here here here and here the other big advantage of the Robertson though is that the metal corner brackets bits themselves are slightly tapered so it means that you get quite a good transfer of force all the way around the screw head and you’ll find if you try Robertson outdoor screws it feels like a really positive fit between the metal corner brackets and the screw but you’ve still just got four points of force transfer the two big disadvantages with Robertson though is that they’re not self-centring and they’re only used by a tiny fraction of people in the UK not saying don’t use them if it was a choice between Robertson or hex I would pick Robertson any day but for me personally. Outdoor Screws Large metal corner brackets. Metal corner brackets for wood. Heavy duty metal corner brackets. Long metal corner brackets. Metal corner brackets screwfix. Decorative metal corner brackets. Corner brace brackets. L brackets.
Outdoor screws screwfix. Railway Sleeper Brackets. Screwfix railway sleeper brackets. Railway sleeper brackets b&q. I think better alternatives have been developed now than around thirty years later around 1934 the Philips screw head was born it was actually invented by a guy called John P Thompson but he sold his design on to Henry Phillips and the Phillips screw company was born again we’ve got four points of force transfer onto the head of the screw so here here here and here and the Phillips outdoor screws also had the advantage as well that there’s a slight taper on the head of the metal corner brackets bit which means that there’s a bit more flexibility in terms of using the same metal corner brackets for different size outdoor screws but we’ve still essentially just got four points the force transfer a couple of years after that in 1936 the hex head was developed by Bauer and shower.
T gonna brush over that but the hex head does have the advantage that were now putting six points of contact on this screw head the hex head outdoor screws are still used today in flat pack furniture but really they’re being overtaken by stalks no which will come to a little bit later on the next big development was then in 1962 when GKN outdoor screws and fasteners developed the posi drive system quasi drive look exactly like Phillips outdoor screws except we’ve got these little markings here at 45 degrees to the main cross and that’s how you know it’s a posi drive screw it’s actually very different to a Phillips screw and the big difference is that in addition to the cross that you would have on a Phillips screw we’ve now got these extra four points of contact between the screw driver and the screw it’s a bit misleading with having these little lines here those lines don’t really do anything other than signify that it’s a posi drive screw so if I just hide those out the road but we’ve got these little grooves in the corner here at 45 degrees to the main cross and of course.
