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  • Flathead screws, why?
  • chipps
    Full Member

    I’ll caveat by saying that I’m not actually a carpenter, engineer or even hobbyist DIYer, but I have recently been doing some jobs around the house (see the ‘2 min jobs that take you ten years’ thread for inspiration) and I fitted a couple of curtain rails.

    Now, the screws to attach the mounts to the walls have nice Phillips screws and rawlplugs, but the screws to keep the rail on to the mount (and the mount on to the wall mount) are flat head screws, one of which you have to screw in, blind, from above.

    Why are they using flat head screws? They’re a pain to locate the driver in the slot, slip out and burr really easily and I wonder why everything isn’t all cross head these days? I appreciate that, in theory, you can tighten a flat screw tighter, but is that actually the case? Are there any chippies/engineers in the house care to defend the flattie?

    jambourgie
    Free Member

    Agreed. Whatever happened to square drive? That sounds the best. Phillips are a pain in the anoos too tbh.

    thisisnotaspoon
    Full Member

    Agreed. Whatever happened to square drive? That sounds the best.

    Square drive is more likely to round than hex, reason being that although 90deg corners put more pressure perpendicular on the flats, it’s not enough to compensate for having 50% less points of contact.

    Phillips are a pain in the anoos too tbh.

    Mostly because people try to use the wrong size Philips, or use a cross head screwdriver as they don’t know the difference.

    Fun fact, cross head screws are designed to slip. They were intended to be used on production lines in the days before torque limiting drivers were available so you could just screw in the bodywork on your Ford Model T until the driver spun on the head without worrying about breaking the screw. Phillips was then developed at a later date to solve this.

    Why are they using flat head screws?

    Cheap to make, someone somewhere saved a few pence when ordering a few million of them, and a few million hours of humanity’s collective endeavors were lost fitting them.

    Cougar
    Full Member

    I appreciate that, in theory, you can tighten a flat screw tighter, but is that actually the case?

    No.

    It’s probably just cheaper.

    ernielynch
    Free Member

    Are there any chippies/engineers in the house care to defend the flattie?

    I assume you mean slotted screw heads and obviously it depends on situation but the answer imo is “paint”.

    Try cleaning out three coats of paint from a Philips screw head and then do the same with a slotted screw head.

    Also a buggered slotted head is usually easier to deal with than a buggered Philips head.

    I agree that in most cases though pozi/philips is preferable

    somafunk
    Full Member

    It’s easier to remove paint/varnish from a flat screw head than a Philips screw head

    goldfish24
    Full Member

    Is there also something going on with materials here too? I’m guessing, but I imagine you can’t form a nice pozi or Philips head in a decorative brass screw.

    RustyNissanPrairie
    Full Member

    ‘coz flathead screws look nice all aligned in the same direction. You have aligned them haven’t you?

    TrailriderJim
    Full Member

    flathead screws look nice all aligned in the same direction

    It’s called clocking. Flathead screws if you want a retro / cleaner / simpler look. Otherwise, can’t see much point.

    BigJohn
    Full Member

    Almost all my wood screws are Pozidrive, which is a bit like Phillips, but not enough that I ever use a Phillips bit and vice versa. Some wood screws, and masonry screws that I use are Torx and my pocket hole screws are Robinson (square hole). Most self-tappers and metal screws are Phillips but some of my windsurf fin bolts are Pozi and some Phillips so I have to carry a PZ3 and a PH3 driver in my kit box.
    Using an impact driver I never get a PZ head to slip. Phillips though are designed to cam out under excess load to avoid stripped threads.
    You can tell a PZ screw because there are little lines at 45 decrees to the slots and the driver has little extra peaks at 45 degrees to the main blades, although there peaks don’t engage with anything.
    I have a lot of screwdrivers.

    igm
    Full Member

    You’ve all missed the point.

    So we can buy more high end tools.

    dyna-ti
    Full Member

    Philips screws are used in engineering/electrical. Shelves as in carpentry will always be pozidrive, or increasingly these days torx.

    thepurist
    Full Member

    While we’re on the topic, do old slot head screws always have a ridiculously narrow and shallow slot that doesn’t fit 99% of modern screwdrivers, or have I just been unlucky?

    ernielynch
    Free Member

    have I just been unlucky?

    No. Otherwise you would appreciate that narrow and shallow is better than wide and deep which makes screw heads prone to splitting in half. Try unscrewing a slotted screw with only half a head.

    thisisnotaspoon
    Full Member

    The paint point makes sense, the only other place they have a right to be is in any adjusters so you can see what you’re doing.

    Is there also something going on with materials here too? I’m guessing, but I imagine you can’t form a nice pozi or Philips head in a decorative brass screw.

    The yellow colour on screws is just something they do to the zinc coating to make them look nice.

    Mostly because people try to use the wrong size Philips, or use a cross head screwdriver as they don’t know the difference.

    I just realized I got pozi and philips mixed up 🤦‍♂️, isn’t there a 3rd and 4th version as well, there’s a version of philips without the cam-out action, and there’s JIS as well, or is that the same thing?

    maccruiskeen
    Full Member

    99% of the reason most people think they are terrible at DIY is because they use the screws that come in the packet with whatever curtain rail / shelf bracket or whatever. Even decent quality hardware comes with terrible fixings

    Whether they’re slotted, or Philips or Pozdrivei (Philips and pozidrive aren’t the same but they look so similar most people can’t tell the difference but they’ll perform badly with the wrong driver) they’ll usually gave poorly formed heads, blunt points, shallow threads and so on and will frustrate people’s efforts to use them

    Slotted screws aren’t the best in many applications – particularly now that a.lot of screw driving is done with drill drivers, but they’re not fundamentally bad –  most people’s experience of slotted screws is of badly made slotted screws.

    Murray
    Full Member

    Whatever happened to square drive?

    Henry Ford couldn’t agree a licence deal so only used them in Canada. And for pocket screws.

    didnthurt
    Full Member

    For aesthetics on things like door handles, socket face plates etc.

    Small and big screws have them as they’re easier to make and tighten. Also you can always get a flat screw tighter thant a pozi, that’s why electrical terminals often have both on the same screw head.

    Terminal-Screw-Washer-Assemblies-Electric-Fasteners-Manufacturer

    dc1988
    Full Member

    I thought it was just because they look prettier

    spooky_b329
    Full Member

    Some wood screws, and masonry screws that I use are Torx and my pocket hole screws are Robinson (square hole). Most self-tappers and metal screws are Phillips but some of my windsurf fin bolts are Pozi and some Phillips so I have to carry a PZ3 and a PH3 driver

    No screwdriver set is complete without a set of JIS screwdrivers, one you have a set you’ll find they are all over the place. They also seem to work well on other types of crosshead

    Sandwich
    Full Member

    but I imagine you can’t form a nice pozi or Philips head in a decorative brass screw.

    More likely it’s due to material softness. You can’t drive brass straight into something with a powered tool, pilot hole first or the screw will snap. Similarly pull down too hard on a countersunk screw and the head will come off.

    bfw
    Full Member

    I read on a Tamiya forum/thread the other day that Japanese use JIS standard screws and drivers. 45 years or working on Tamiya, RC, Jap bikes and cars and I have just found this out!!

    mahowlett
    Free Member

    Shimano use JIS screws everywhere as well, which is why none of my screwdrivers ever fit well in the derailleur adjusters and always slip out.

    tthew
    Full Member

    When my local pub was refurbished a few years ago, all the wall light fittings, shelf brackets and general wall tat with exposed fittings were put up with big steel countersunk Pozidrive screws. Looks aesthetically horrible, I have sometimes contemplated taking a big pocket full of black dome headed replacements and tidying it up myself. 😁

    Cougar
    Full Member

    Also you can always get a flat screw tighter thant a pozi, that’s why electrical terminals often have both on the same screw head.

    I don’t think is true.

    Even if it were, if you were tightening up electrical sockets so tightly that it required a specific screwdriver type over another then you’d likely destroy either the end of the wire or the terminal itself. And the screw would only have whichever drive was required, not both.

    (and that photo ain’t Pozidriv😁)

    You can’t drive brass straight into something with a powered tool, pilot hole first or the screw will snap.

    … which is exactly what Phillips screws are for, the driver will (or at least should) cam out before the head snaps.

    sobriety
    Free Member

    I came here to mention JIS screws, watch for the dot on what looks like a philips screw, that dot means that it isn’t!

    I have JIS screwdrivers for working on classic Japanese motorbikes, they’re lovely, they either undo the screw or tear the head neatly off, allowing the stub to be easily unscrewed with molgrips after the fact. No more camming out!

    joshvegas
    Free Member

    Slot heads require an appropriate screwdriver*

    You can apply more torque without having to apply alot of axial pressure. which is less key on the way in but on the way out is vital.

    Essentially slotheads on hinges and anything that maybe removed over it’s life time will benefit from not being trashed by repeated use.

    *Wood handle beasts for woodworking stuff.

    Slots and powertools lies madness.

    kayak23
    Full Member

    Slotted screws have been responsible for more than one screwdriver/hand interface.

    Don’t like them however, Torx can properly GTF.

    joshvegas
    Free Member

    I swear I replied before.

    With a proper screwdriver slots can transmit transmit more torque which is useful on the way in but it’s really on the way out that it can make a mega difference. So door screws are slotted so you have much more chance of getting them back off. Good luck with a Philips or posy that’s been stuck in a frame for 2years and probably half mangled on the way in.

    willard
    Full Member

    All the pros here in Sweden use torx on the screw heads. It’s better.

    kayak23
    Full Member

    With a proper screwdriver slots can transmit transmit more torque which is useful on the way in but it’s really on the way out that it can make a mega difference. So door screws are slotted so you have much more chance of getting them back off. Good luck with a Philips or posy that’s been stuck in a frame for 2years and probably half mangled on the way in.

    Not sure that applies these days. My impact driver could spin the planet if the planet had a 1/4″ drive. You can use your whole body weight to lean in if needs be. Incredible torque.
    Of course, if the screw has been put in by someone who can’t modulate a driver and has been chewed up, then it’s different.

    Hinges shouldn’t really be painted anyway. A nice shiny hinge with matching screws should be left as is. Shame to fill it with white gloss, though obviously it does happen…a lot.

    blokeuptheroad
    Full Member

    A decent screwdriver makes a huge difference with slotted screws. Cheap DIY ones with a wedge shaped profile vertical profile are the worst for chewing up slots.  I have a driver and bit set that was sold as a gunsmiths set, but I use it for everything where a cordless electric driver is OTT. The key thing about it though is that the slotted bits are hollow ground, so they get a really good purchase on the insides of the slot for the whole depth of it. That and the fact there are loads of different sizes so you always get a perfect fit. I’ve had it for 20 years and it’s my most used tool.

    maccruiskeen
    Full Member

    All the pros here in Sweden use torx on the screw heads. It’s better.

    they’re good when they’re good, but they have their short comings  – one is that 3 sizes of pozi bit will deal with every size of wood screw you’re likely to encounter working in wood – and you’ll use one of them 95% of the time, my bit box has got 7 different Tx sizes in it and if you lose or break one you can’t really get by with one of the others – where as you can often coax a PZ1 or PZ3 screw with a PX2 driver

    The other is it puts a lot of onus on the manufacturer to make good quality bits which it seems even the better manufacturers aren’t able to do – I laid new floorboards the other week and used clever little lost head screws that go in through the tongue. Each box of 200 came with two Tx10 bits – they’d last for about 30 screws, presumed the ones sold with the screws wouldn’t be great quality so got a Bosch one out of my kit – it was done after 10 screws,  Bought a 5 pack of dewalt ones – the whole pack of 5 lasted for….. 6 screws! and one of them was still sticking out of the board. Bought 10 Wera ones (which meant going to 3 different shops) and bought two more packs of screws just rob the driver bits out of them they just about got me to the end of the job  – laying  a staggering….30 floorboards, one and half packs of screws – not exactly epic other than the time spent shopping.

    By comparison a pack of 10 descent PZ2s lasted me 8 months on a job where we got through over a £million worth of timber and fixings.

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