Long screwfriver,I know that it usually works but why?

[File HandleParticipant @filehandle]

Whilst trying to remove a stubborn outdoor slotted screw today, it initially refused to turn. So I then resorted to one that is 3 times as long. It then turned with ease. I often do this, but I have never really understood why it works. Ok the wooden handle on the longer one was a little fatter, but don;t see this as making such a large difference. I have seen it suggested that a slight tilt on a long screwdriver increases the moment of force, but it can’t be that much or the blade will slip out of its slot. Can anyone explain why this happens?

I like wooden handled screwdrivers and have restored about 20 from their previous neglected / abused state so it is always easy to find one that fits a slot.

[MichaelRParticipant @michaelr]

It’s down to the larger handle on your long screwdriver, you can apply more torque and grip with the larger handle.

MichaelR

[renardiere7Participant @renardiere7]

Have a look at this.

 

https://blog.lostartpress.com/2013/05/31/the-relative-advantages-of-long-and-short-screw-drivers/

[MichaelRParticipant @michaelr]

I based my reply to the posters question by my experience when serving my time in the 1950s if we got stubborn screws we used what they call a London pattern screwdriver it had a handle with flats on both faces you could really get a good grip and torque, they generally shifted the stubborn screw.

MichaelR

[Michael GilliganParticipant @michaelgilligan61133]

The alternative answer  is that the long screwdriver winds-up as a torsion spring and is storing energy.

MichaelG.

[Grindstone CowboyParticipant @grindstonecowboy]

I do remember reading this fact in an old motorcycle book (1930s), but it didn’t explain the reason(s).

Rob

[Ches Green UKParticipant @chesgreenuk]

renardiere7

Have a look at this.  https://blog.lostartpress.com/2013/05/31/the-relative-advantages-of-long-and-short-screw-drivers/

The 21 Comments below the article you link to make interesting reading. Thanks.

My gut instinct is that the longer screwdriver has a larger radius handle, and probably better purchase. And, with the handle being further away from the screw head, it allows the bigger muscles to be used rather than just ‘wrist’ muscles.

Ches

[Andy StopfordParticipant @andystopford50521]

I’ve always favoured the slightly-tilted-greater-leverage explanation.

But could the handle diameter make the difference? I’ve just tried a not very scientifically rigorous experiment using the screwdriver handle and extension bars from my 1/4″ drive socket and screwdriver bits set.

I drove a couple of screws into a piece of MDF, one with just the handle, one with the extensions, as tight as I could turn:

The screw on the left was driven with just the handle, the one on the right with the extensions. The right hand one has sunk deep into the MDF whilst the other has barely sunk to the depth of the countersink; no pilot holes were drilled.

I think that gives a reasonable demonstration that the handle is not the deciding factor (though it certainly makes a difference).

Ideally, to investigate further one would use some more accurate torque measuring device – one of those moving pointer torque wrenches would be good.

 

[roy entwistleParticipant @royentwistle24699]

Andy   You’ve introduced another factor here,  cross headed screws. Try it again with slotted

Also you are tightening them not undoing. As an aside my dad always called screwdrivers turnscrews and spanners were nut keys.

Roy

[Andy StopfordParticipant @andystopford50521]

Can’t do that I’m afraid Roy. I got rid of all my slotted screws when I retired (in fact I had to poke around to find screws with ordinary threads – I mostly have the fancy fluted ones which drive too easily to make good “test instruments”).

An undoing test would certainly need a torque wrench-type of measurement methinks.

I usually used the Yankee for undoing stubborn screws – 430mm overall length (unextended, not counting the bit), but the handle isn’t that much bigger than shorter screwdrivers – about 40mm diameter at its widest, as against 35mm for a 220mm long Wiha electrician’s screwdriver.

Older books use ‘turnscrew’ (which the spell checker has just underlined), I wonder if ‘screwdriver’ was originally an Americanism – it sort of sounds like it could have been.

[Robert Atkinson 2Participant @robertatkinson2]

Ahh, the good old Yankee. Over 20 years ago I attended some trade shows in the USA. I was technically visiting but the company was also displaying so of course I helped with unpacking and setting up our stand. Everything was packed in large crates with screwed down tops and sides. The fitter who was supposed to be setting up had a battery electric screwdriver. He laughed when I pulled a full size Yankee out of my bag, asking what is that, an antique? It was actually brand new and he wasn’t laughing when he found it was about 3-4 times faster than his electric. Additionally it was much less likely to slip and damage the screw head and it didn’t need charging. No good on small items though.

On the long driver debate I’m in the “gives you room to let you get your weight behind  it” school.  Being able to build up a bit of torque in a long thin shaft can help too. I have some 1/4″ hex drive bits with a long thinned section to allow torque build-up with electric drivers.

Robert.

[BazyleParticipant @bazyle]

As Roger implies above, I think your posture changes with the longer driver. My favourite for applying torque is a driver bit in a brace. One of our Shedders as his dementia took hold like to hammer screws in and contended screwdrivers were only for removing them.

[Grindstone CowboyParticipant @grindstonecowboy]

I’ve heard that from a couple of joiners, and I believe, at one time, a hammer was known as “a Brummagem screwdriver”.

Rob

 

[John HaineParticipant @johnhaine32865]

I agree that a longer driver makes it easier but I don’t buy the “torque build up” argument. The torque at the screw head equals the torque applied at the handle statically. I think it’s to do with being far enough from the job to get a good stance and get your weight on the axis to stop the driver keying out.

[Robert Atkinson 2]

On Robert Atkinson 2 Said:

Ahh, the good old Yankee…he wasn’t laughing when he found it was about 3-4 times faster than his electric. Additionally it was much less likely to slip and damage the screw head and it didn’t need charging.

I’ve had those conversations too.

Another fun thing with the Yankee is that inadvertently triggering the release collar can punch the bit through the customer’s plasterboard wall. You need not ask me how I know.

[JAParticipant @ja]

I just find long shafted screwdrivers easy to use.

JA

[File HandleParticipant @filehandle]

Thanks for all of the comments. I measured what I think are the relevant dimensions, ignoring length. Small screwdriver handle 36 mm long 53, which will obviously give more torque. But something else which I realised as I have the screwdrivers, although both have the same thickness of blade their widths are different, 7.4 and 12.4 mm. This also made a difference. perhaps the 2 combined made up for the difference in ease of removal. I was also up a ladder undoing the cover on the external alarm box. I can also believe that the difference in length made it easier to apply more force to the handle. I just surprised at the difference, and had expected the need to put an adjustable spanner on the flat of the cabinet screwdriver or get a brace and screwdriver bit. sadly the alarm box was beyond repair and needs replacing.

[PeteParticipant @pete41194]

Tbh, I agree with others and can’t think of any reason within the laws of physics how a longer length of screwdriver shank might somehow be capable of increasing the torque to make removal easier. A different body stance, larger handle diameter or even shape to increase grip I could understand and agree with. But the screwdriver shank length isn’t magically increasing the torque.

How much torque a screw head might withstand? There’s also the large difference between the cheap, cold headed, usually softer and mass produced slotted screws. And those with machined slots present on much of what we might own. Metrology equipment for example. Many machine tool manufacturer’s in the past used the same type, South Bend for another example. Sadly, and what most manufacturer’s seem to pass off today as an acceptable screwdriver tip shape someone might mistakenly use while removing those screws with machined slots couldn’t be any worse. I did the same at one time and buggered up my own share of screw heads until I read why that happens.Those common tapered tip screwdrivers we all own apply the torque right at the top of the screw slot which is the absolute weakest area of the head. Increasing the torque with those for any stubborn or tight screws almost guarantees visible screw head damage, part of the head breaking off, even the tip camming out of the slot and damaging the screw head even more, Or worse, sometimes damaging the surrounding area of the screw location. A fine gun stock as a common example.

For some uses, the inherent design flaws of those tapered tips may not matter.  An online search for the type of slotted screwdriver tip design sold to and used by gunsmiths, instrument technicians, watch and clock makers and many others  would show that none of them use those taper tip screwdrivers. And for very good reasons. The proper tips would be parallel ground, chosen to properly fit the particular screws full slot length, depth, and with almost zero clearance to fully fit inside the slot width. Depending on what else is available, you can then apply more than enough torque that the screw will loosen without any damage, or the head shears off. My tapered tip screwdrivers gather a lot more dust on them than they once did, and it would now be a rare screw that can’t be removed without damage.

[Clive FosterParticipant @clivefoster55965]

Agree with Pete about the poor shape of many standard screwdriver tips.

The rise of the 1/4″ hex bit sets certainly seems to have resulted in rather better, even if not up to gunsmith standards, tip shapes being more generally available. Also easier and somehow more acceptable to bin a worn tip rather than a whole driver too. Although I do tend to keep my pozi and phillips bits going too long. but compared to most of my building trade related pals I’m very light on tools so everything lasts way longer in my hands.

I really liked the plastic “more or less cabinet” handle range Stanley used to make. Not only were the tips of respectable quality but colour coding made life that bit easier. Blue for Pozi, red for phillips and green for plain if I recall correctly.

Always make sure I have one of the basic ratchet drivers for 1/4″ bits with me when working out of the shop or offsite. Much kinder on stubborn screws than a normal driver or electric beast. Generally I find the cheap, sheet metal affairs more handleable than the proper ratchet version.

I vote for handle style being important with longer screwdrivers. Most of my long ones are electrical / electronic types with relatively small diameter round with flue handles. Shank length seems to make little difference to how hard it is to shift well tight screws.

Clive

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