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  #1  
Old 02-02-2013, 12:25 PM
Bones Daley Bones Daley is offline
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Why is a long screwdriver more efficient than a short one ?

Every craftsman knows this to be true, but the question is, why is it so ?

I could see if the screwdriver were being used as a lever, then the extra length would give a mechanical advantage, but when the screw slot, the blade and the wrist are all in the same line, with the same central axis, then you would think that a short stubby driver would be just as efficient as a long bladed driver.

But it isn't ...
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  #2  
Old 02-02-2013, 12:35 PM
HardlySanguine HardlySanguine is offline
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At a guess it's because the longer ones usually have bigger handles that you can grip better and get your whole hand around. Shorter ones, even if they have big handles probably don't leave enough space for your hand and arm to do its twisty-wristy movy-woovy stuff (this is how carpenters talk, right?)
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  #3  
Old 02-02-2013, 12:36 PM
Amateur Barbarian Amateur Barbarian is offline
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Because it contains more vodka. Duh.

(HS has it right, IMHO.)
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  #4  
Old 02-02-2013, 12:51 PM
Bones Daley Bones Daley is offline
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Quote:
Originally Posted by HardlySanguine View Post
At a guess it's because the longer ones usually have bigger handles that you can grip better and get your whole hand around. Shorter ones, even if they have big handles probably don't leave enough space for your hand and arm to do its twisty-wristy movy-woovy stuff (this is how carpenters talk, right?)
Not so, I have to say, although that is a natural assumption.

A 12 inch long screwdriver has ample space for the twisty-wristy movy-woovy stuff (and yes this is exactly how carpenters speak) but a 2 foot long driver with exactly the same handle is much more efficient
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  #5  
Old 02-02-2013, 01:04 PM
Amateur Barbarian Amateur Barbarian is offline
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Quote:
Originally Posted by Bones Daley View Post
A 12 inch long screwdriver has ample space for the twisty-wristy movy-woovy stuff (and yes this is exactly how carpenters speak) but a 2 foot long driver with exactly the same handle is much more efficient
Cite, explanation or justification?
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  #6  
Old 02-02-2013, 01:16 PM
Stranger On A Train Stranger On A Train is offline
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It all has to do with the mechanics of how you handle the screwdriver. With a stubby screwdriver, there is usually only enough room to hold it with one hand (the driving hand), which has to be held from the end. This means that in addition to the applied torque and axial force (to keep the head fo the driver in the slot), lateral force is applied by the same hand to ensure that the screwdriver is in line with the axis of the fastener. With a longer driver, the non-driving hand is typically used to ensure alignment. This may not seem like a lot of force until you look at the lateral torque that has to be applied to keep a screwdriver in line. The axial force is applied on the gripping area of the handle rather than at the end, which gives more traction for torque (the entire finger length and upper palm) than holding it from the end with just the fingers, as a stub screwdriver is often held. It is also the case that it is easier to visually assure alignment with a longer screwdriver (longer length allows the user to see that the angle is off-normal) and in tight spaces the longer shaft may allow a better hand position (see the discussion of applied torque above).

Stranger
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  #7  
Old 02-02-2013, 01:19 PM
Bones Daley Bones Daley is offline
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Originally Posted by NitroPress View Post
Cite, explanation or justification?
Thirty years as a carpenter, that's the cite. You don't believe me, go ask any carpenter.

The explanation of the phenomenon is what I am trying to find out here, from people smarter than I ...
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  #8  
Old 02-02-2013, 01:40 PM
Amateur Barbarian Amateur Barbarian is offline
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Quote:
Originally Posted by Bones Daley View Post
Thirty years as a carpenter, that's the cite. You don't believe me, go ask any carpenter.

The explanation of the phenomenon is what I am trying to find out here, from people smarter than I ...
Um, thirty years of anecdotal evidence isn't proof that the longer driver is more efficient, especially not when you're insisting that the difference between one foot and two is significant. Between a stubby and anything longer, perhaps. But I really think you need to establish the effect before we get too deep into any purported cause.

I have about forty years of tool-handling experience* myself, more as a mechanic than a carpenter - frankly, I've used a screw-gun for the last twenty years in carpentry and construction; there's efficiency for ya - and have a pretty good sense of what works, what doesn't and why. Show any evidence that a two-foot screwdriver is "more efficient to use" than a one-foot one, and we can move on.

*Shaddup, smartass.

Last edited by Amateur Barbarian; 02-02-2013 at 01:44 PM..
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  #9  
Old 02-02-2013, 01:40 PM
RadicalPi RadicalPi is offline
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Quote:
Originally Posted by Bones Daley View Post
Thirty years as a carpenter, that's the cite. You don't believe me, go ask any carpenter.
Do you have a published cite? It's necessary because the claim, at least on its face, is implausible. That, however, does not mean false, and that's why me and others are looking for cites.
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  #10  
Old 02-02-2013, 01:46 PM
johnpost johnpost is online now
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Stranger On A Train has it.

if you use a longer driver one handed you may find it more difficult, it's harder to keep on axis.

with lots of practice you can develop techniques using shorter drivers one handed and stay on axis.
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  #11  
Old 02-02-2013, 01:51 PM
Musicat Musicat is offline
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I have a long, thin, Philips screwdriver I call my "second favorite tool." It is about the only tool I need to fix or install computers. I can't say it's more efficient than a shorter one, but it has two characteristics I like:
  • It can reach deep in cabinets or in narrow places
  • It can "twirl" to rapidly insert or remove a screw, something a shorter driver with less weight can't do as well.
And I magnetized the tip, so it can insert or remove screws in hard-to-reach places, too.
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  #12  
Old 02-02-2013, 01:55 PM
Bones Daley Bones Daley is offline
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No published cites, but as I say, ask any carpenter who has ever had to remove rusted screws from the hinges on an old door. He will vouch for the fact that using a 2 foot screwdriver in that situation is a hell of a lot more efficient than using a 12 inch driver.

Now, I am not suggesting that using a 3 or four foot screwdriver would be even more efficient, I think 2 foot is about the maximum efficiency.

The more I think about it (and I have never given it a great deal of thought before), the more I believe that it is all to do with being able to get your shoulder directly above the wrist, which enables you to exert maximum torque ...
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  #13  
Old 02-02-2013, 02:19 PM
casdave casdave is offline
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It depends upon the size of the screw.

Smaller than a certain size means you will have difficulty keeping it online, but once you start getting to the larger sizes of screw than it helps enormously if you can get your shoulder behind the force you need, and you'll find on a shirt screwy that you just can't do that. Once you get longer screwies than that though, you will find it is harder to keep straight, and also you may find some twisting of the screwie itself.

For those of us non-wood butcher types, it is always much better to have a screwy that is the exact size of the head you are screwing - the less play in the head the better
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  #14  
Old 02-02-2013, 02:22 PM
Mangetout Mangetout is offline
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The difference between a stubby screwdriver and a standard one is going to be about handling (as Stranger On A Train said).

The difference between standard and two-feet-long - if there is any difference - is going to be what? - either torsional springiness in the shaft, or just the fact that if you drive it with one hand and steady the tip/screw with the other, you're using your arm drawn right back (although that doesn't immediately seem very much more comfortable or efficient to me).
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  #15  
Old 02-02-2013, 02:26 PM
Tim R. Mortiss Tim R. Mortiss is offline
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This discussion is moot until you decide what you are defining efficient to mean.
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  #16  
Old 02-02-2013, 02:28 PM
Fubaya Fubaya is offline
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Nope, a longer screwdriver provides the same torque, as long as the shaft and handles are identical, of course. They may provide you with a better grip or get it closer to your body where your muscles can get more leverage, but otherwise, like I tell all my dates, length doesn't matter.
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  #17  
Old 02-02-2013, 03:17 PM
Bones Daley Bones Daley is offline
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Quote:
Originally Posted by casdave View Post
It depends upon the size of the screw.

Smaller than a certain size means you will have difficulty keeping it online, but once you start getting to the larger sizes of screw than it helps enormously if you can get your shoulder behind the force you need, and you'll find on a shirt screwy that you just can't do that. Once you get longer screwies than that though, you will find it is harder to keep straight, and also you may find some twisting of the screwie itself.

For those of us non-wood butcher types, it is always much better to have a screwy that is the exact size of the head you are screwing - the less play in the head the better
You've pretty well nailed it ..(or maybe screwed it)

The increased efficiency of the longer (2 foot) length of driver is apparent when you are trying to remove really recalcitrant large gauge screws (such as in old door hinges) and the increased efficiency is undoubtedly because you are able to use your shoulder and elbow to exert greater torque than you could with a shorter driver.

Worth pointing out btw that in the "old door" situation, with slotted screws as opposed to Phillips or Robertson screws, the impact driver and cordless screwdriver are useless ...you need an old fashioned screwdriver (with the correct size of tip, natch ... )

For normal use, with properly drilled pilot holes , the difference is negligible.
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  #18  
Old 02-02-2013, 04:16 PM
Amateur Barbarian Amateur Barbarian is offline
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Quote:
Originally Posted by Bones Daley View Post
The increased efficiency of the longer (2 foot) length of driver is apparent when you are trying to remove really recalcitrant large gauge screws (such as in old door hinges) and the increased efficiency is undoubtedly because you are able to use your shoulder and elbow to exert greater torque than you could with a shorter driver.
I'm still waiting for a validation of the difference between a one-foot driver and a two-foot driver. I just tried and can get exactly the same position and leverage, relative to a flat surface, with both. The footlong was much easier to handle as well.

Is it that the extra foot is needed to clear beer-gut distance?
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  #19  
Old 02-02-2013, 05:18 PM
The Librarian The Librarian is offline
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The difference comes from the fact that it is easier to properly align a longer tool.
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  #20  
Old 02-02-2013, 05:58 PM
california jobcase california jobcase is offline
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I think the screwdrivers that have square shanks are better than the round shank ones. Makes it easy to add a wrench for some awesome torque, regardless of screwdriver length.
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  #21  
Old 02-02-2013, 08:14 PM
Fir na tine Fir na tine is offline
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Originally Posted by california jobcase View Post
I think the screwdrivers that have square shanks are better than the round shank ones. Makes it easy to add a wrench for some awesome torque, regardless of screwdriver length.
Torque? You want some f'ing torque? Get an old fashioned brace and bit driver. Your biggest problem is going to be snapping off the heads of the screws!
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  #22  
Old 02-02-2013, 08:25 PM
genuinejon genuinejon is offline
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A longer blade feels smoother because some of the force goes into twisting the blade. This smoother feeling allows me to provide the maximum force I have available for my grip strength without fearing that I'm going to strip the skin off of my hand or lose my grip and bust a knuckle. This may or may not be the 'efficiency' the OP is describing.

Quote:
Originally Posted by california jobcase View Post
I think the screwdrivers that have square shanks are better than the round shank ones. Makes it easy to add a wrench for some awesome torque, regardless of screwdriver length.
Some screwdrivers have a ratchet hole in the top, too.
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  #23  
Old 02-03-2013, 08:50 AM
HoneyBadgerDC HoneyBadgerDC is online now
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I have a 3 ft long screwdriver in both philips and flat, I also use a 3 ft 3/8 drive speed handle and extensions a lot. The simple reason is that you don't need room for arms or hands. All you need is the narrow space that will allow the driver to fit. You have better vision with your hands and arms out of the way and are better able to grip the driver at a maximum leverage. You don't have to bend or stretch as far to reach things either. Working at a table I prefer a 12" mainly for the clear vision reason.
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  #24  
Old 02-03-2013, 09:57 AM
DSeid DSeid is online now
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Quote:
Originally Posted by NitroPress View Post
I'm still waiting for a validation of the difference between a one-foot driver and a two-foot driver. I just tried and can get exactly the same position and leverage, relative to a flat surface, with both. The footlong was much easier to handle as well.

Is it that the extra foot is needed to clear beer-gut distance?
Will you accept the query modified as: "Why do so many who use tools perceive a longer screwdriver to be be able to transmit more force?"

It is clear that the op is not the only one whose experience is such. A quick google gives quite a few other times this question has been asked on other sorts of fora by other tool users (usually with the same sorts of speculations as responses).

Answers seem to fall into groups focusing on the ergonomics (which muscles can get recruited and how how feet can get planted and/or grip and/or screwdriver alignment) to suggestions that not all of the force is rotational -- that to some small degree some straight out leverage comes into play as the screwdriver goes slightly off exact axial orientation. To your belief that those who experience this are just imagining it.

To those who do experience it -- does it happen as much no matter where the target screw is located? Horizontally above or below you versus vertically oriented in a door frame?
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  #25  
Old 02-03-2013, 10:11 AM
temp user temp user is offline
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Quote:
Originally Posted by Bones Daley View Post
Every craftsman knows this to be true, but the question is, why is it so ?

I could see if the screwdriver were being used as a lever, then the extra length would give a mechanical advantage, but when the screw slot, the blade and the wrist are all in the same line, with the same central axis, then you would think that a short stubby driver would be just as efficient as a long bladed driver.

But it isn't ...
I have experienced the exact same phenomenon as you, OP, and I too am in agreement that there are times when I have tackled a stubborn screw that a longer screwdriver will do the job better than a shorter one. I have no cites, but I have always assumed that the difference experienced was a matter of leverage.
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  #26  
Old 02-03-2013, 10:21 AM
TriPolar TriPolar is online now
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As far as I can tell, the effect and it's cause has been described here well. You get better control of the alignment of the screwdriver, and you can position yourself better to get a good grip and exert maximum torgue on the handle.
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  #27  
Old 02-03-2013, 10:37 AM
johnpost johnpost is online now
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Quote:
Originally Posted by california jobcase View Post
I think the screwdrivers that have square shanks are better than the round shank ones. Makes it easy to add a wrench for some awesome torque, regardless of screwdriver length.
when doing this you need to put your body into it and press the driver hard into the screw; if you don't then you will tear up the screw head.

there are also offset screw drivers, tips that fit a ratchet wrench which also require the same care in use.
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  #28  
Old 02-03-2013, 11:56 AM
Amateur Barbarian Amateur Barbarian is offline
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I don't think there is any argument that a longer screwdriver is easier, better, more efficient (in application of effort and ease of maintaining position, so further argument of the point is, IMHO, unproductive.

I am still waiting for any kind of validation that a VERY long driver (2 feet) is "better" than a "long" driver (1 foot), all other things being equal.

No argument at all that a 9-12 inch driver is easier to use, if there's room to do so, than a stubby or shorty.
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  #29  
Old 02-03-2013, 12:15 PM
TriPolar TriPolar is online now
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Quote:
Originally Posted by NitroPress View Post
I am still waiting for any kind of validation that a VERY long driver (2 feet) is "better" than a "long" driver (1 foot), all other things being equal.
Considering the consensus in this thread for the reasons why a longer screwdriver seems more 'efficient', there isn't going be an ideal length. The location of the screw and the individual wielding the tool are going to determine the ideal length. If the OP has found a 2 footer best for him in most cases, and uses it more often as a result, that will reinforce his skill with that screwdriver and it will be more effective for him in more circumstances. Since it's pretty rare for people to have screwdrivers available in 1inch increments from 1 to 3+ feet to figure out what is ideal, we're all going to adjust to certain lengths from a smaller set of choices.
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  #30  
Old 02-03-2013, 02:05 PM
DrCube DrCube is offline
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I think the longer screwdrivers are just bigger. Bigger handle, bigger tip, which gives you more torque. I don't think it has anything to do with the length per se, it's just that longer screwdrivers tend to be bigger around and provide more torque.
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  #31  
Old 02-03-2013, 02:48 PM
robert_columbia robert_columbia is online now
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Originally Posted by Tim R. Mortiss View Post
This discussion is moot until you decide what you are defining efficient to mean.
This is a good point. "efficient" could mean reducing any of the following things:

1) The total energy (e.g. calories burned) used by the person using the screwdriver to accomplish a task.
2) The strenuousness of physical exertion required. E.g. the short screwdriver requires the person to burn 3 calories by an intense muscle effort over a 30 second period, while using a long screwdriver still burns 3 calories but with easy, low-sweat movements over a period of 2 minutes.
3) The time necessary to complete the task, regardless of how hard the person must work or how tired it makes them. This metric is likely to be the one that management would favor.

Last edited by robert_columbia; 02-03-2013 at 02:48 PM..
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  #32  
Old 02-03-2013, 03:14 PM
Amateur Barbarian Amateur Barbarian is offline
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Quote:
Originally Posted by TriPolar View Post
Considering the consensus in this thread for the reasons why a longer screwdriver seems more 'efficient', there isn't going be an ideal length.
The OP made an unsupported claim that longer screwdrivers are more efficient, which I'm willing to let pass based on the discussion here... but he also made the specific claim that a two-footer (far larger than most people have) is "more efficient" than a one-footer and that "every craftsman knows this."

Maybe the latter will fly over on Garage Journal or a DIY forum, but it stays challenged here until there's some kind of objective proof.
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  #33  
Old 02-03-2013, 03:21 PM
Manlob Manlob is offline
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A longer screwdriver is less stiff in torsion than a short one. With the same applied torque a longer screwdriver will have a greater twist angle and more stored elastic strain energy than the short screwdriver. When there is enough torque to overcome the static friction holding the screw in place, it will rotate slightly and the torque required to keep it rotating will drop (kinetic friction vs. static friction). With a short screwdriver, the torque will drop quickly with screw rotation angle and the screw will stop after a small amount of rotation. For a long screwdriver, the torque will drop more slowly as the screw rotates, allowing the screw to turn over a greater angle.

If you consider dynamic loading effects, the peak torque you can apply should also be greater for a long screwdriver. While ramping up to maximum torque, you reach a higher angular velocity with the long screwdriver, which gives some inertia to help overshoot the maximum torque you are capable of applying slowly.
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  #34  
Old 02-03-2013, 03:42 PM
ZenBeam ZenBeam is offline
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Quote:
Originally Posted by Manlob View Post
A longer screwdriver is less stiff in torsion than a short one. With the same applied torque a longer screwdriver will have a greater twist angle and more stored elastic strain energy than the short screwdriver. When there is enough torque to overcome the static friction holding the screw in place, it will rotate slightly and the torque required to keep it rotating will drop (kinetic friction vs. static friction). With a short screwdriver, the torque will drop quickly with screw rotation angle and the screw will stop after a small amount of rotation. For a long screwdriver, the torque will drop more slowly as the screw rotates, allowing the screw to turn over a greater angle.

If you consider dynamic loading effects, the peak torque you can apply should also be greater for a long screwdriver. While ramping up to maximum torque, you reach a higher angular velocity with the long screwdriver, which gives some inertia to help overshoot the maximum torque you are capable of applying slowly.
You're right that a longer screwdriver will have a greater twist angle (all else being equal), but I think that twisting works against you, not for you. There'll be loss, in the form of heating the shaft, due to that twisting. Also, I'd expect a more "spongy" shaft will give you less control over the tip, and make the tip more likely to slip.

I'd expect that the trade-off for an optimal length, in terms of being easier to use, is between less of an angle of the shaft for a given hand movement, favoring a longer screwdriver, and less twisting of the shaft, favoring shorter screwdrivers.
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  #35  
Old 02-03-2013, 05:00 PM
Projammer Projammer is offline
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Another thing to consider is the wobble when you're working on a hard to turn screw. A longer tool is easier to keep aligned with the screw. Two inches of wobble on an eight inch screwdrivers is a lot more deflection than two inches of wobble on a two foot screwdriver. And the harder you're having to turn, the more likely you are to be moving the handle around.
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