Were Phillips screwdrivers designed to "cam-out"?

I generally do not fair well with the square drive, certainly better than slot but not by much. Torx is hard to beat. good reading, so was reading about the standardization of screw threads.

There’s a few things I don’t get in this thread.

First off, what’s up with the infatuation for square drive, torx, etc? They are by far the worst (along with inside hex) when it comes to clearing paint, varnish and corrosion build-up, which is usually the greater part of gaining purchase on a difficult screw head. Square drive can get utterly ruined by rusting out, requiring quite some creative work (sacrificial use of torx bits). Torx suffers from rapid bit wear when using poor quality screws, something I learned installing communications gear in racks.

Second, why all the hate for slotted screws? They are by far the easiest to deal with once the going gets tough, and I can consistently twist the head off one regardless of what it’s been through. There’s a whole lot of additional advantages (ease of improvisation, tool availability, etc), but that takes care of the complaint. The only real drawbacks are that they can’t be machine driven rapidly, and it takes a certain level of skill to drive them by hand.

Also, there seems to be some misconception that the screw head pattern makes a big difference when it comes to removing stuck fasteners. Removing a badly corroded screw is always difficult, twisting the head off is always easy.

Phillips, for one. The trick is to use good quality hardware. Here’s a Yamaha OEM screw holding my Wera LaserTip PH2 at a considerable downward angle. You can wave that combination around all day without issue:

Here’s a short clip of me removing a ruined cross-headed screw from the bottom of a garbage collection boat that had been up on the beach so many times that the screw heads were worn literally beyond recognition. Based on the general dimensions I guess they were PZ3s, but they came out with PH2 bits, no problem:

Finally, here’s a rather contrived clip demonstrating the wonders of slotted heads, which also demonstrates the proper removal procedure for a ruined screw. This is a brand new, high quality M6 slotted screw in AISI 316, which I have mangled on purpose until the screw driver wouldn’t bite. The head is peened down until the pattern starts looking pinched, and the screw driver is driven down into the head, creating a perfect match. This works every time, no matter which pattern:

(Pending resolution of technical difficulties)


I’m going to assume that you’re familiar with both Machine Thinking and Clickspring? Either way this is a good subject for another thread…


My view is square drive for construction in timber where the fastener is stainless or encapsulated by coating and is not likely to be disturbed after assembly.
Torx head or socket head for metal to metal assembly.
Slot head for fastenings in 316 stainless on the yacht.

Some of the worst days of my life involved a Phillips fastener in some way.


You are wise beyond your years Chief Catherder, the youngsters on your staff should benefit by keeping their ears open. My son was not engine, but would have learned a bit from you at a very welcome breakfast, lunch or dinner. Sorry you didn’t cross paths.

@Klaveness As far as the slotted screws, good ol Lou agrees with you and for the same reasons. In other videos I’ve heard him say he wouldn’t use any other type of screw on a boat.

Yup, subscribed to both. Got a whole list of machinists I keep tabs on.

Different screw heads are suited for different applications. There isn’t a screw head that the best in all conditions. If a screw head gets covered with paint and has to be removed with basic tools, the flat head is probably the easiest to gouge the paint out of. Robertson and Torx and are not easy to clean paint out of but have their own uses whether assembling wood furniture or electronic components.

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Here’s how it’s done. I learned this trick during my apprenticeship from Markku Tuominen, legendary ninja master of classic Hondas, may god rest his memory. It’s an essential skill when working with classic motorcycles.

For the demonstration I use a high quality PZ2 headed 4.8mm wood screw in A4. Normally I would have extracted it with a PZ bit due to the angles, but the discussion is about PH, so here you go. The bit needs to have a truncated tip, and for this reason I use a PH3 rather than grinding down a PH2, which would require less force to swage. Despite being harder to move, other materials are usually easier to work with. You can get better engagement than I show by spending a bit of time, but my intention was only to demonstrate that you can handle a worst case scenario in less than a minute.