Why are larger screwdriver sizes longer?

[Mike83]

In general, why is a P3 screwdriver longer than a P1 and so on? In my experience, larger screws aren't any harder to access than small ones. I am aware that long and short lengths of all sizes are made, but in general screwdrivers get longer as the size increases.

 

[tw33k2514]

I wonder that as well. The other day I needed a PH#3 to remove a screw that was holding my door panel on. And I had to stand a million miles away to turn the giant screwdriver. Very inconvenient.

 

[HandyManny]

larger diameter scews have more contact surface on the threads. That means a bit more force is needed to overcome that contact tension and turn them. Longer shafts will give you a bit more torque ability when 0° straight from the screw head. Of course a 90° angle gives you much more torque. Just a theory. I really don't know.

Just waiting to see if someone here will flat out say: YOU'RE WRONG!!

 

[showags]

I would contend that since more torque is generally necessary to turn said fastener, the handle is longer in order to ensure the best possible turning position can be obtained. In other words, in the case of a screw that is in an open space, with a longer handle, you will better be able to stand next to the screwdriver to increase your own leverage on the screw. Think about it, how much torque can you generate when your arm is extended out in front of you? Then compare that to how much could be generated with a bent elbow and hand located close to the body. Of course, this is all assuming the screw is out in the open. For tight places, I have to agree with the above.

 

[The Muffin Man]

Longer shafts will give you a bit more torque ability when 0° straight from the screw head.

Just waiting to see if someone here will flat out say: YOU'RE WRONG!!

Handy, your wrong.

 

[Mike83]

larger diameter scews have more contact surface on the threads. That means a bit more force is needed to overcome that contact tension and turn them. Longer shafts will give you a bit more torque ability when 0° straight from the screw head. Of course a 90° angle gives you much more torque. Just a theory. I really don't know.

Just waiting to see if someone here will flat out say: YOU'RE WRONG!!

That explains the larger handles on larger sizes which allow a better grip and also apply the turning force at a longer arm for more torque. Shaft length does not play into the equation unless you are using the screwdriver as a prybar

 

[Mr.Nutcase]

not really..... The length sometimes helps, ie P2 stubbies to 6in P2 screwdriver

 

[Rigmaster]

Handy, your wrong.

+1


Unless you have something to back up your claim.......

 

[rsanter]

visual proportion
someone a very long time ago set an arbitrary standard and everyone else has followed it like sheep

in the case of slotted screwdriver, it because they make better prybars that way

bob

 

[HandyManny]

+1


Unless you have something to back up your claim.......

See Mr. Nutcase post above yours. What's your argument against it? All that needs to be backed up is for you to use a stubby driver then use a longer driver on the same screw.

 

[HandyManny]

Handy, your wrong.

You beat him to it. I was expexting that one from Nissan Crawler

But seriously, can you prove it? I haven't heard your explanation yet.

 

[The Muffin Man]

See Mr. Nutcase post above yours. All that neesds to be backed up is for you to use a stubby then use a longer driver on the same screw.

So Sir Issac Newton lied to us?

please read this http://en.wikipedia.org/wiki/Torque

 

[The Muffin Man]

But seriously, can you prove it? I haven't heard your explanation yet.

Newton did a long time ago.


read the above link.


A wider handle can increase torque, not a longer shaft. This is why you can exert more torque on a faster using a ratchet and bit socket than a screwdriver.

 

[HandyManny]

That explains the larger handles on larger sizes which allow a better grip and also apply the turning force at a longer arm for more torque. Shaft length does not play into the equation unless you are using the screwdriver as a prybar

It does play a little into it. I can tell a difference when using a longer screwdriver as opposed to a stubby one. But, not sure if this is the only reason why P3 is usually longer than a P2 or P1.

 

[HandyManny]

Okay Muffin Man! Tell us exactly what is the main reason that P3 drivers are longer than a P2 or P1! Com'on, you know you know, so tell us.

 

[rinny_tin_tin]

That explains the larger handles on larger sizes which allow a better grip and also apply the turning force at a longer arm for more torque. Shaft length does not play into the equation unless you are using the screwdriver as a prybar

For more torque - you need a longer handle - thus some basis for the greater overall length

 

[HandyManny]

Still waiting for Muffin Man to come up with a sound explaination for the length.

 

[The Muffin Man]

Okay Muffin Man! Tell us exactly what is the main reason that P3 drivers are longer than a P2 or P1! Com'on, you know you know, so tell us.

I don't know, I'm just letting you know that your theory is wrong. However, I do know a few things regarding physics .

PH1 and PH2 shafts maybe shorter to reduce torsion since the shaft is thinner.

 

[HandyManny]

I don't know, I'm just letting you know that your theory is wrong. However, I do know a few things regarding physics .

PH1 and PH2 shafts maybe shorter to reduce torsion since the shaft is thinner.

But if you don't know, the how can you be so sure my theory is wrong? It may very well be, I'm not saying it's right. Just relating what my observations have been regarding the usage with longer shafts.

I understand the whole torsion thing and in that regard it sounds like a good theory. Maybe PH3 are longer because they can be due to the thickness of the shaft.

 

[The Muffin Man]

But if you don't know, the how can you be so sure my theory is wrong?

Did you read that link I posted

 

[M5 LiTE]

For more torque - you need a longer handle - thus some basis for the greater overall length

Huh? You could have a a big azz screwdriver with a mile long shaft and it will not be able to impart more torque on a screw than with a screwdriver with an inch long shaft if the handle diameter were the same on both.

If used as a prybar, yes. But when used as a screwdriver, then a WIDER head, like a T-Handle, would allow you to apply more torque to rotate a screw.

To help visualize, imagine a stubby 1/2" ratchet vs a 24" long breaker bar - with which can you apply more torque to the fastener?

In order to apply torque, you need to apply the force PERPENDICULAR to the fastener.

 

[garfunkle24]

larger diameter scews have more contact surface on the threads. That means a bit more force is needed to overcome that contact tension and turn them. Longer shafts will give you a bit more torque ability when 0° straight from the screw head. Of course a 90° angle gives you much more torque. Just a theory. I really don't know.

Just waiting to see if someone here will flat out say: YOU'RE WRONG!!

Sorry, but you are wrong.

In theory, a longer shaft would actually reduce the torque to the fastener due to torsional losses. This same reason is why you should be setting your torque wrench slightly above the specced torque when using it with extensions.

But I also do not know the reasoning behind bigger drivers having longer shafts. Maybe they just assume that those big fasteners aren't generally used in tight access locations.

 

[HandyManny]

In order to apply torque, you need to apply the force PERPENDICULAR to the fastener.

We could all agree on that, the key word being "Perpendicular". Of course someone here may still come out and tell you your wrong

 

[HandyManny]

Sorry, but you are wrong.

In theory, a longer shaft would actually reduce the torque to the fastener due to torsional losses. This same reason is why you should be setting your torque wrench slightly above the specced torque when using it with extensions.

But I also do not know the reasoning behind bigger drivers having longer shafts. Maybe they just assume that those big fasteners aren't generally used in tight access locations.

Hey listen guys! I never opened my post with the saying that my theory was right. In fact if any of you go back and read it carefully you will see what I'm saying. My reference to being wrong was in a humorous response to replies I see from certain individuals on this forum and how they relate to others here. Didn't mean to convert you all to be like those few.

Someone asked the question and I replied with a guess as many post above have.

 

[The Muffin Man]

Someone asked the question and I replied with a guess as many post above have.

Then we said that your guess is wrong and provided factual evidence as to why .

 

[HandyManny]

Thanks Muffin. Just illustrated my point!

 

[JakeD]

Perhaps it's just that larger, thicker screwdrivers are longer because they can be. A thin, long shafted screwdriver would have a tendency to be easily bent and destroyed.

 

[skeletonizer]

visual proportion
someone a very long time ago set an arbitrary standard and everyone else has followed it like sheep

in the case of slotted screwdriver, it because they make better prybars that way

bob

This is the best response so far IMO.

 

[Stuey]

For more torque - you need a longer handle - thus some basis for the greater overall length

A longer handle does nothing for torque. It's the radius about which force is being applied. In other words, the width of the handle is the dominant factor.

I don't know, I'm just letting you know that your theory is wrong. However, I do know a few things regarding physics .

PH1 and PH2 shafts maybe shorter to reduce torsion since the shaft is thinner.

I think that longer shafts can handle greater amounts of torsion.

Consider that in tightening a screw or whatnot, high torque results in 20° of twist between the handle and the driver tip. Let's consider that the capacity to endure torsion before failure is 5° per linear inch. If you're using a 3" driver in these conditions, there may be a high probability of failure. If you're using a 6" driver, torsional stress will be distributed about a greater length, thus lowering the probability of failure.

Now, I may be wrong, but as far as I can tell my logic is relatively sound.

In theory, a longer shaft would actually reduce the torque to the fastener due to torsional losses. This same reason is why you should be setting your torque wrench slightly above the specced torque when using it with extensions.

What's your reasoning behind this?

 

[krusty the clown]

visual proportion
someone a very long time ago set an arbitrary standard and everyone else has followed it like sheep

the only sane person posting to this thread is rsanter

 

[Moose-LandTran]

I think it's because you need more leverage when using them as prybars..

 

[Delray]

Might be the idea behind it is to make it easier to quickly pick out the size you need.

 

[Merkava_4]

To say the least, if they were all the same length, it'd be harder to tell the difference in sizes at a quick glance.

 

[The Muffin Man]

I think that longer shafts can handle greater amounts of torsion.

Consider that in tightening a screw or whatnot, high torque results in 20° of twist between the handle and the driver tip. Let's consider that the capacity to endure torsion before failure is 5° per linear inch. If you're using a 3" driver in these conditions, there may be a high probability of failure. If you're using a 6" driver, torsional stress will be distributed about a greater length, thus lowering the probability of failure.

Now, I may be wrong, but as far as I can tell my logic is relatively sound.

I think you are right Stuey. I'm sure that the design of the screwdriver incorporates a torsion fatigue failure that is beyond the torsion generated by torquing the fastener. That being said I'd doubt that shaft length isn't related to head size for torsion reasons.

 

[Mike83]

I doubt torsional strength of the shaft is the limiting factor in a hand tool like this. The screw or tip will fail first. The concept is true - a longer shaft will allow more twist and thus lower the torsional stress.

 

[caper]

Because engineers design **** to be pleasing to the eye so you'll buy it.They usually don't know what you really need.Case in point,I've been trying to find a flat bladed screwdriver with a half inch wide tip and a short shank,like 2 inch max,and a regular handle.Everything I've seen has shanks 12 to 24".Totally useless to try and turn a brass screw with,cams out everytime.I know it exists,a guy in our other shop has a noname one he picked up at a yard sale,but try to find one in this day and age.

 

[AdamMopar]

I doubt torsional strength of the shaft is the limiting factor in a hand tool like this. The screw or tip will fail first. The concept is true - a longer shaft will allow more twist and thus lower the torsional stress.

The last statement is false. The shear stress is not dependent upon shaft length. Only the angular deflection is.

 

[AdamMopar]

I think that longer shafts can handle greater amounts of torsion.

Consider that in tightening a screw or whatnot, high torque results in 20° of twist between the handle and the driver tip. Let's consider that the capacity to endure torsion before failure is 5° per linear inch. If you're using a 3" driver in these conditions, there may be a high probability of failure. If you're using a 6" driver, torsional stress will be distributed about a greater length, thus lowering the probability of failure.

Now, I may be wrong, but as far as I can tell my logic is relatively sound.

The last statement is false. The shear stress, due to torsion, is not dependent upon the shaft length.

 

[garfunkle24]

What's your reasoning behind this?

Here is what I started to write but I decided to check some facts before posting:

One good example would be torque steer in a fwd car due to unequal length drive shafts. The longer shaft (of equal O.D typically) will 'twist' more than the shorter one. Any input energy which is being used to create torsion stresses in the shaft is energy that is not being transferred to the output.

Note that I was speaking about how much torque is applied to the fastener, not how much torque the shaft will withstand. Also Note that I said "in theory" as this would be undetectable at this scale.

As with most things, the more I looked into it, the more complex the problem became.

My initial post and half-realised follow-up would have been 100% correct if I had started them with "given a set input rotation".

In looking into and thinking on this some more, I come to realise that once the shaft has reached it's limit of elastic torsional deformation, all of the input forces would be transferred to the load. But then of course, you haven't truely reached the limit of torsional deformation in the shaft. With increasing torque input it would spiral like an EZ out and eventually shear off...

I think my initial assertions may be correct in theory, but less so in practical terms.

 

[kindyr]

I think the marketing reason has the most application here. Very likely they make the sets to have the same proportions as the typical set of combination wrenches. With wrenches, the torque issue applies more, and so the brain comes to accept that the bigger fastener needs the longer tool, even if physics doesn't agree with it.

though has anybody seen a set of combination wrenches that is the same length for the entire set? would be interesting, though I don't think the public would accept it after it's ingrained to the standard angles of groth in wrenches