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Comment by samwillis | Hacker News Reader

Here in the UK most new screws are Pozidriv, but many people confuse them with Philips as they are very similar. Mixing up Pozidriv/Philips results in the driver riding out and damaging the head. It should be required teaching in schools the difference between the two!

Pozidriv screws have a small engraved cross at 45 deg to the main recess. The drivers have a small matching flute in the grooves.

Nice picture here: https://www.finehomebuilding.com/2015/09/16/what-is-the-diff...

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PZ are useless as a standard because it's not significantly different enough from others, and you can't tell which PZ you need. Torx and hex is brilliant because you can easily say which shape of bit you need, and you'll instantly know if you pick the wrong one.

Luckily Torx seems to have finally won and screws that require any kind of moment (construction/decking/fasteners/) now seem to use them in stores, while only the kind of scre you'd hang up a picture frame with is PH/PZ.

I have never seen a square (Robertson?) screw in the wild, I assume that's regional.

Worse than useless, that makes them actively harmful.

I'm glad I know pozidrive now.

Most of the cement board screws I've used (for installing shower tile) are square head; I've not done much shower work so I don't know if that's a trend or just what the store has at the time.

My fleetwood mobile home built in the late 90s was assembled entirely with square head screws, hex head lag bolts, glue, and a lot of staples.

"I have never seen a square (Robertson?) screw in the wild, I assume that's regional."

Simpson makes very large diameter, 4" stainless steel screws that I rather like:

#12 x 4", model number is S12400DBB

... those are 306 stainless but if you want 316 you would get T12400DBB.

IF we use screw fasteners in framing, we typically use GRK 3-1/8"-#10 but once in a while we just want something beefier and those simpson 4"-#12 are fantastic ...

... and they are square drive.

Being from Europe (Sweden) I can't remember having ever seen a square drive screw. Torx is slowly becoming the standard here.

We get some Simpsons stuff in Europe (like nail plates and beam hangers) but I don’t think the screws are sold in Europe. If they were I don’t think it would be very easy to introduce a square bit screw in s as market where they are unknown.

And obviously, not much uses any imperial naming. I think this is regionally produced because e.g a beam hanger for 45mm timber has to be pretty close to 45mm and a 2” won’t do.

> I have never seen a square (Robertson?) screw in the wild, I assume that's regional.

Reasonably common here in Australia. Our decking screws are either Torx or Square Drive.

> I have never seen a square (Robertson?) screw in the wild, I assume that's regional.

Almost exclusively Canadian I believe.

You can get them though, I bought a Kreg pocket hole jig in the UK which came with some for some reason, and had no problem getting bits for them (Amazon I think).

I'd never seen them (IRL) before that either.

They're readily available in the US as well. I've mostly used them with pocket holes.

They’re absolutely everywhere in Canada, so much so that it’s easy to forget that they’re not used everywhere. As a curiosity for anyone non-Canadian, if you were going to go to the hardware store and get screws to screw together some dimensional lumber (e.g. 2x4s), what kind of drive would you expect to find? I’m not even sure if I could find 3” wood screws here that aren’t Robertson.

Standard would be pozidriv, probably PZ2. You could certainly get torx if you preferred though (or Phillips or flat, if you really hate yourself!) - UK.

> Torx and hex is brilliant because you can easily say which shape of bit you need, and you'll instantly know if you pick the wrong one.

In my experience, a problem with Torx is that it is a common mistake to use a bit one size smaller than what it should be. It will still engage just fine, but if you apply too much force, you'll destroy the bit, or head, or both. I find it a lot harder to notice when I pick the wrong size Torx bit, compared to a Philips or Pozidriv.

I have made this mistake a lot when using Torx. I have learned myself to always test a bit one size larger than what I think I need, just to be sure.

Always test the bigger bit in Torx if you don't know which bit you should use. Though many (larger) boxes of Torx screws come with one or two bits.

Yeah, I haven't used Torx, but the author listed 100 sizes as a feature, and I'd strongly disagree. I think Robinson having a small number of sizes makes it extremely obvious when you're using the wrong one, and you can almost always tell the correct Robinson to use by sight alone. (the author lists 6 sizes, but in practice 100% of applications I've seen have used one of three)

Not sure how many sizes of Torz there actually are, but I have only seen T10,15,20,25,30,35,40 which is 7 sizes. I think I saw a smaller one in a precision screwdriver set next to the other weird iPhone/watch ones like tiny pentalobes. But effectively Torx for all normal applications is one of 7 sizes, with T20 and T25 being probably 95% of all wood screws for building/carpentry applications.

I wasn’t aware that there could even be a “T17” or “T31” - simply because no one would ever do it. Increments of 5 is already close enough to some times guess wrong.

In my experience appropriately sizing Philips is basically impossible unless the screw itself is marked. The #2 is way more common it seems so that helps with the default but if you know it isn’t #2 then you are screwed (har har) because many different size drivers will ‘fit’ and ‘work’.

Yeah for this exact reason I despise torx. The last couple of cars I've owned have tonnes of torx screws, and as they rust and accumulate road grime over the years they change size. You will only be able to fit a T20 into an arch liner screw to start with, then as you turn it the rust and dirt dislodges, and it either becomes the next size up or cams out and rounds off. In weaker metals they round hilariously easily (torque wrench set to 20NM on a sump plug, torque wrench set to 7NM on a brake disc set screw).

My experience of Torx screws in high torque applications (bolting together Bosch high pressure diesel pumps) also makes them seem flawed, as the small contact area results in damage to the screw (hardened, awful to drill out, yet still round off with an almighty crack when enough pressure is applied, hence needing to drill out) or damage to the thin ends of the Torx driver itself 50% of the time.

When I lived in Southern Florida, I did some volunteer work for Habitat for Humanity. They used Robertsons for sheet rock.

Now that’s really interesting! In Canada, where Robertson is almost ubiquitous, Sheetrock screws are one of the few exceptions in construction that still use Philips-head screws; usually with a special bit that forces the driver to cam out once the head is flush with the wall.

https://www.homedepot.ca/product/dewalt-drywall-dimplers-3-p...

"I have never seen a square (Robertson?) screw in the wild, I assume that's regional."

The way I heard it was that Mr. Robertson gave his new screws to Henry Ford for testing. Ford wanted to use them but Robertson insisted on a royalty per screw. Ford would not agree to that so the deal failed. This is probably the reason they are a regional rather than an international screw. The entire electrical hardware industry uses square heads in Canada.

(Source: Probably CBC radio many decades ago (?) )

All deck and floor screws are also Robertson in my part of Canada. I've seen drywall screws in both Robertson and Philips however.

Canadian here. I have been using Robertsons for forty years. It's all you can get at the hardware store: #10/black-handle screwdriver, #8/red, #6/green and #4/yellow. They are a joy to work with. They're so good nobody will buy the old straight slot or Philips.

Slide a screw onto the screwdriver. Hold it horizontally. Holds fast. Can you do that with Torx?

Yes, absolutely, and even better than Robertson does.

The way I'd describe Torx to someone who is used to Robertson is that Torx is like Robertson, only more so. That is, all the things you'd consider the strengths of Robertson are things that Torx is better at.

Agreed, having used both kinds I find Torx tend to hold better. Not sure if the tolerances are tighter, but I’ve come across Robinson that tend to be a bit loose and it’s much easier to strip.

Torx fit very snuggly and even the smaller bolt is hard to strip as long as you have the right but size.

Peter Robertson (the inventor) is Canadian and Robertson screws are very popular there as you mentioned. They exist elsewhere in varying degrees.

For example, I live in Southern California and I haven't seen them at the hardware store until recently. I found one behind a wall-plate in my home several years ago when I was changing a light switch. Thankfully, I'm Canadian, so I already had the right tool -- right next to the unspent Canadian Tire money in my toolbox. ;)

Yeah the legend goes something like Robertson tried to get Henry Ford to use them but wanted too much money to license the design. As an American the only Robertson screws I've ever seen came from the subwoofer enclosure on my car… which I imported from Canadia.

I see Robertson on Decks/Decking mostly --they are stainless or rust resistant so their necks/shanks don't weaken over time. Others rust and when you try to take them out they shear off easily.

I had never seen a square screw until I put together a wood playhouse. From the information in this thread it seems to be used in wooden things?

Something that took me an embarrassing long time to realize was that North American electrical outlet binding terminals are a combination slotted/Robertson screw head. The Robertson is great.

Klein tools makes combination head tools that engage both, which is fantastic if you are upgrading a bunch of outlets.

Pozidriv exists almost entirely because the old patent expired. It is not sufficiently better than Philips that the overall fastener situation is improved by its existence.

Imo that's the main failure of the posix, it _looks_ like a Phillips, and behaves like one of you use a Phillips bit. Which is rather unfortunate and not really it's fault, but hard to overlook for "normal" usage.

A little harsh to call an intentional compromise 'a failure'.

A feature is that pozi is compatible with Phillips bits, just without its advantages.

For people with older or smaller toolkits, that's actually quite helpful.

Pozidriv screws are definitely better than Philips but they're still pretty awful. They're basically the second worst fastener in common use.

Holy crap, is that what PZ means on all my bits? No wonder they don't really work right for Phillips.

I'm having the same revelation. Just setup a kit that had about 100 pz screws. The whole time I was thinking "man these screws suck!"

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