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Qwercus

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Found a screwdriver nearly 33 inches long. I can't imagine any need for that length, except to reach some deep inaccessible places. Still I suppose it's always good to have a big'un, as the Actress said to the Bishop.
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Stigmorgan

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I'm probably wrong but doesn't a longer driver give more turning force? I've always found it easier to undo a screw with a long screwdriver over a short stubby one.
 

AES

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I'm probably wrong but doesn't a longer driver give more turning force? I've always found it easier to undo a screw with a long screwdriver over a short stubby one.

Yeah, me too. I have no maths, etc, to prove it, but I too always had the "feeling" (sorry!) the longer the screwdriver the more torque I'm applying
 

Adam W.

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I think it has something to do with ergonomics and the way you grip a long turnscrew.
 

Spectric

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Yeah, me too. I have no maths, etc, to prove it, but I too always had the "feeling" (sorry!) the longer the screwdriver the more torque I'm applying
You could be losing torque due to torsion in the longer length, it is this which gives you that feeling but a larger diameter handle would allow you to apply more torque easier.
 

Inspector

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A long handle keeps the tip engaged therefore putting more force into the screw. It does so because the natural wobble as you work it, say a 20mm circle, has a smaller effect the further you are from the tip. It is why you have an easier time using a longer screwdriver compared to a stubby. That is a nice old tool, likely that long for access. My first thought was for a mechanic, locomotive or marine, but the handle is just too clean.

Pete
 

Phil Pascoe

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I used to have a pair of two foot long ones specifically kept for removing the mounting screws under wash basins. You couldn't keep straight on the screw with drivers much shorter.
 

gcusick

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You could be losing torque due to torsion in the longer length, it is this which gives you that feeling but a larger diameter handle would allow you to apply more torque easier.
The torque at the screwdriver tip must be the same as at the handle - unless the handle turns independently.
 

Adam W.

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Or the screwdriver shaft is winding up like a rubber band, which is highly unlikely.
 

cmoops2

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This will be a very familiar tool for Avro Vulcan groundcrew - such long screwdrivers were used to release the engine bay door fasteners when standing below the aircraft (no need to use steps, ladders, staging etc).
To close the doors, one erk would hold the door in its closed poition using the screwdriver while another went round securing all of the fasteners - simples !
 

AES

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Or the screwdriver shaft is winding up like a rubber band, which is highly unlikely.
Actually, not so unlikely as you may assume. For example, in turbo prop aero engines (i.e. a gas turbine driving a propeller via a gearbox) measuring torque is an essential in flight parameter, and in most of these engines, torque is measured by looking at the amount of twist on the drive shaft as power is applied (or reduced) by the turbine. Looking at those shafts, it's almost inconceivable that such a shaft could twist (even just a tiny bit of course). But they do.

So I'm not surprised that if a screwdriver blade is correctly engaged in the screw head, and if the handle can be gripped well, it actually IS possible that the screwdriver shaft does indeed twist a tiny little bit - of course not the rubber band that Adam suggests, but yup, a tiny tiny bit.

The above IS my serious "guesstimate" BTW.
 

Spectric

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Yes even something like a crankshaft which looks very solid can twist and lead to torsional vibration, or in FWD vehicles where the two drive shafts are very unequal in length due to the gearbox not being central and the longer shaft is a larger diameter tube to offset torque steer.
 

gcusick

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Actually, not so unlikely as you may assume. For example, in turbo prop aero engines (i.e. a gas turbine driving a propeller via a gearbox) measuring torque is an essential in flight parameter, and in most of these engines, torque is measured by looking at the amount of twist on the drive shaft as power is applied (or reduced) by the turbine. Looking at those shafts, it's almost inconceivable that such a shaft could twist (even just a tiny bit of course). But they do.

So I'm not surprised that if a screwdriver blade is correctly engaged in the screw head, and if the handle can be gripped well, it actually IS possible that the screwdriver shaft does indeed twist a tiny little bit - of course not the rubber band that Adam suggests, but yup, a tiny tiny bit.

The above IS my serious "guesstimate" BTW.
Absolutely right. But the torque at the driven end of the shaft (the screwdriver handle) and that at the driving end (screwdriver tip) will be the same.

Let’s simplify things, and consider a 1-dimensional case. Imagine a weight resting directly on a surface. The force at the surface is exactly the weight (or the mass x (acceleration due to gravity), to be pedantic). Now pick the weight up, an interpose a compression spring between it and the surface. What’s the force now? It has to be the same, or the weight would either sink into the surface, or float away. The principle holds for torque as well.
 

AES

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OK, "so far so good" (I think)! But consider also:

QUOTE: Absolutely right. But the torque at the driven end of the shaft (the screwdriver handle) and that at the driving end (screwdriver tip) will be the same. UNQUOTE:

So if applying torque to the screwdriver handle (WITH the driver blade securely located in the slot) does indeed "wind the screwdriver shaft up like a rubber band", will the shaft not "repel" that force and wind itself back the other way to its original "at rest" position (even while I continue to apply my full torque "constantly" to the handle? If YES, then surely that "unwinding force" is ADDING TO (or should it be SUBTRACTING FROM) the torque I'm applying at the handle????

I must say, "I dunno" and I'm confusing myself now. I only "know" that in the real world if I want to undo a really tough screw I'm better off with a long 'un than a short 'un (as the Bishop said to the actress)! :)

I think the reality is that as I think it was Inspector said above, because the torque I'm applying to the handle is never (or very rarely) exactly vertical to the whole "assembly", I'm actually just experiencing a bit of extra "leverage" because of the side to side wobble of my hand. Dunno really, "my brain 'urts"! (And isn't the answer to your Q "IT depends on the compression strength of the spring"?). :dunno:
 

Woody Alan

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The extra force you are able to apply is becuse you have got your hand and arm tighter into your torso and body mass instead of having arm more extended.
 

IWW

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The extra force you are able to apply is becuse you have got your hand and arm tighter into your torso and body mass instead of having arm more extended.
Possibly, & I'm sure body position is a big factor, but I'm not sure that is the whole answer. I & a few of my contemporary apprentices made the same observation (that you seem to be able to apply more torque with a longer driver than a short one), many decades ago. It holds for me whether I'm in a comfortable body position or working awkwardly as you sometimes have to do. I've often tried to come up with a rational explantion, too and the best I could do was the same as AES, that when the shaft isn't exactly coaxial with the screw, you are gaining a little leverage (something a 'fat' handle also offers). You can't hold the driver off-axis very much without danger of it slipping out of the slot, so in fact we try to keep it as close to coaxial as we can. But with a long shaft, the radius of the same off-axis position will be greater than with a short shaft, giving you some extra leverage.

But I had an early career change & ended up involved in scientific research, where I learnt how much subjectivity affects our observations, so if you think a longer handle gives you more un-doing power, that's how it will seem. Be that as it may, I do think the effect is real, so I wish someone with the right gear & too much time on their hands would set up a proper experiment & put the matter to rest for us... :)

BTW, I've got one of those monster drivers (found it in FIL's kit) and it comes in mighty handy once a year or so to remove a really stubborn old slotted screw (a species that is rapidly heading for extinction!). My previous go-to was a driver bit in my brace. As long as the slot hasn't been stripped out by previous less well-armed attempts at undoing it, no screw can resist that combination. You can bear down on the bit with all your weight to get maximum purchase in the slot & easily apply enough torque with the brace to move the screw - or shear it off! For that reason I prefer to give the monster driver first dibs at removing a stubborn screw; it gets 90% or more moving, with far less risk of shearing the head off....
Cheers,
 

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