Maker Pro
Maker Pro

Driving screws ...

A

Arfa Daily

Jan 1, 1970
0
Totally off topic, but just for a bit of intellectual amusement ...

Why should the length of a screwdriver's shaft, affect the amount of torque
able to be given easily to the screw head ? This is something I learnt many
years ago as an apprentice. I have just fitted a new 'antique' bog roll
holder to one of my toilet rooms. The screws that came with it were nice
single slot chrome plated jobs to match, but were about 2" long. When I came
to drive them into the plastic wall plugs, I didn't want to use a power
driver for fear of slipping out of that slot, so I went by hand. By the time
I had got to 1.5" I was really struggling to keep the screw turning. Then I
remembered the long screwdriver trick. I have one about 18" long. The shaft
and tip and handle diameter were all near enough the same as the short
screwdriver I had just been using. Only now, the screws drive in like you're
putting them into a slab of butter. How can this be ?

Arfa
 
M

Mike Paff

Jan 1, 1970
0
Why should the length of a screwdriver's shaft, affect the amount of torque
able to be given easily to the screw head ? This is something I learnt many
years ago as an apprentice. I have just fitted a new 'antique' bog roll
holder to one of my toilet rooms. The screws that came with it were nice
single slot chrome plated jobs to match, but were about 2" long. When I came
to drive them into the plastic wall plugs, I didn't want to use a power
driver for fear of slipping out of that slot, so I went by hand. By the time
I had got to 1.5" I was really struggling to keep the screw turning. Then I
remembered the long screwdriver trick. I have one about 18" long. The shaft
and tip and handle diameter were all near enough the same as the short
screwdriver I had just been using. Only now, the screws drive in like you're
putting them into a slab of butter. How can this be ?

Interesting... Maybe the longer screwdriver lets you apply more
of your arm strength by moving your hand farther away from the wall?

With the shorter one, were you in a slightly more awkward position
and trying to use just your wrist to turn it?
 
A

Arfa Daily

Jan 1, 1970
0
Mike Paff said:
Interesting... Maybe the longer screwdriver lets you apply more
of your arm strength by moving your hand farther away from the wall?

With the shorter one, were you in a slightly more awkward position
and trying to use just your wrist to turn it?

That's a good thought. Maybe. If anyone doesn't believe this, just try it
....

Arfa
 
K

Ken Weitzel

Jan 1, 1970
0
Arfa said:
That's a good thought. Maybe. If anyone doesn't believe this, just try it
...

Hi...

Don't have to try it, been there, done it. Didn't ever get the
tee shirt though :)

I'm old and stroke damaged, so can't explain my theory nearly as
eloquently as I'd like to, but my idea goes something like this...

When you turn the handle against the resistance of the screw, you're
to a small degree "winding up" the shaft. Naturally the longer the
shaft the more you're able to wind it up.

When the screw resists, it's not linear, but rather full of intermittent
and random heavy resistance spots and easy spots.

When the long shaft encounters one of these don't wanna spots,
the shaft winds up until it finally overcomes the resistance.

Someone please explain it better for me :)

Take care.

Ken
 
C

Charles

Jan 1, 1970
0
Arfa Daily said:
Totally off topic, but just for a bit of intellectual amusement ...

Why should the length of a screwdriver's shaft, affect the amount of
torque able to be given easily to the screw head ? This is something I
learnt many years ago as an apprentice. I have just fitted a new 'antique'
bog roll holder to one of my toilet rooms. The screws that came with it
were nice single slot chrome plated jobs to match, but were about 2" long.
When I came to drive them into the plastic wall plugs, I didn't want to
use a power driver for fear of slipping out of that slot, so I went by
hand. By the time I had got to 1.5" I was really struggling to keep the
screw turning. Then I remembered the long screwdriver trick. I have one
about 18" long. The shaft and tip and handle diameter were all near enough
the same as the short screwdriver I had just been using. Only now, the
screws drive in like you're putting them into a slab of butter. How can
this be ?

Have you considered the size of the hand-grip? Longer screwdrivers have
larger handles and thus a torque multiplier.
 
A

Arfa Daily

Jan 1, 1970
0
Ken Weitzel said:
Hi...

Don't have to try it, been there, done it. Didn't ever get the
tee shirt though :)

I'm old and stroke damaged, so can't explain my theory nearly as
eloquently as I'd like to, but my idea goes something like this...

When you turn the handle against the resistance of the screw, you're
to a small degree "winding up" the shaft. Naturally the longer the
shaft the more you're able to wind it up.

When the screw resists, it's not linear, but rather full of intermittent
and random heavy resistance spots and easy spots.

When the long shaft encounters one of these don't wanna spots,
the shaft winds up until it finally overcomes the resistance.

Someone please explain it better for me :)

Take care.

Ken
I'm following that ok Ken, and it's another good thought. There used to be a
little car over here called a Morris Minor, and it employed just what you're
describing, for its front suspension. "Torsion bar suspension" it was
called. A bar a couple of feet long ran alongside the chassis members on
each side. One end was fixed ( but adjustable ) and the other end was
connected to the lower suspension arm. The bar twisted as the suspension arm
moved, and provided the springiness. I think that is what you are thinking
of as being the mechanism at play here.

I might try sticking the business end of the driver in a vise, and seeing if
I can indeed introduce some twist into the shaft.

Arfa

Arfa
 
A

Arfa Daily

Jan 1, 1970
0
Charles said:
Have you considered the size of the hand-grip? Longer screwdrivers have
larger handles and thus a torque multiplier.
Yes indeed, but as I said in the original post, the handles of the two
drivers were much alike, as was the shaft diameter and tip dimension. The
long driver is just that really. A perfectly normal 'average' sized tool,
but with a very long shaft. I originally got it many years ago when I had to
work on some graphics terminals, where the metal cabinet was secured to the
front bezel, by two screws located right in the top corners of the case. The
screws were spring loaded, so had to be driven *very* straight to get them
to locate without cross-threading. The only way to do this was with a
screwdriver 18" long, which was enough for the handle to be outside the back
of the case.

Arfa
 
D

Dave Plowman (News)

Jan 1, 1970
0
Totally off topic, but just for a bit of intellectual amusement ...
Why should the length of a screwdriver's shaft, affect the amount of
torque able to be given easily to the screw head ? This is something I
learnt many years ago as an apprentice.

Just as an aside I was watching a CSI the other night where they were
dismantling something in the lab using a dumpy screwdriver. Which
absolutely no one would use unless forced to by space. The answer was, I
reckon, it made a better framed close up in widescreen...
 
D

DaveC

Jan 1, 1970
0
Why should the length of a screwdriver's shaft, affect the amount of torque
able to be given easily to the screw head ?

My theory goes like this:
Short shaft, you are mostly using the wrist to turn the screw driver. Wrist
muscles tire easily.

Long shaft, you can use your arm and shoulder (which are capable of greater
strength) to rotate the screwdriver via a "locked" wrist (and if not locked,
the twisting motion is shared by the forearm and wrist). Much easier on the
wrist alone, which isn't known for it's strength. Having a longer shaft means
it's easier to use your weight to lean on the screwdriver, keeping it in the
screws' slot. Much harder to do with a short one.

So it's not the screwdriver, per se, but which of the body's muscles you can
put into play that make one screwdriver "easier" than another.
 
A

Arfa Daily

Jan 1, 1970
0
Dave Plowman (News) said:
Just as an aside I was watching a CSI the other night where they were
dismantling something in the lab using a dumpy screwdriver. Which
absolutely no one would use unless forced to by space. The answer was, I
reckon, it made a better framed close up in widescreen...
That's an interesting one Dave, and it kinda backs up what I'm saying. Even
though you would expect to get a good 'torque multiplier' effect from the
fat handle that those dumpies usually have, in fact it is actually very hard
to undo a tight screw, or get a decent tighten on one either. If I'm forced
by space to use one of them, I often finish up with a pair of Mole grips
locked on the shaft to get enough purchase.

Arfa
 
W

WalkingMan

Jan 1, 1970
0
I'm following that ok Ken, and it's another good thought. There used to be a
little car over here called a Morris Minor, and it employed just what you're
describing, for its front suspension. "Torsion bar suspension" it was
called. A bar a couple of feet long ran alongside the chassis members on
each side. One end was fixed ( but adjustable ) and the other end was
connected to the lower suspension arm. The bar twisted as the suspension arm
moved, and provided the springiness. I think that is what you are thinking
of as being the mechanism at play here.

I might try sticking the business end of the driver in a vise, and seeing if
I can indeed introduce some twist into the shaft.

Arfa

Arfa- Hide quoted text -

- Show quoted text -

There were a whole lot of cars over here that used torsion bar
suspension--the Chrysler Corp. By the way one of my neighbors has a
restored Morris Minor, never drives it though.
My 64 Chrysler used the torsion bar idea for keeping the trunk up.
Marshel
 
A

Arfa Daily

Jan 1, 1970
0
DaveC said:
My theory goes like this:
Short shaft, you are mostly using the wrist to turn the screw driver.
Wrist
muscles tire easily.

Long shaft, you can use your arm and shoulder (which are capable of
greater
strength) to rotate the screwdriver via a "locked" wrist (and if not
locked,
the twisting motion is shared by the forearm and wrist). Much easier on
the
wrist alone, which isn't known for it's strength. Having a longer shaft
means
it's easier to use your weight to lean on the screwdriver, keeping it in
the
screws' slot. Much harder to do with a short one.

So it's not the screwdriver, per se, but which of the body's muscles you
can
put into play that make one screwdriver "easier" than another.

Hi Dave
This is the sort of theory that I have been coming around to as well, as I
couldn't see any science that would explain it in terms of the physics of
the screwdriver itself. I mean, you wouldn't expect a rear wheel drive car
with a long prop shaft, to develop more torque at the diff, than one with a
short prop shaft, given a similar engine and gearbox, would you ?

I actually tried to visualize which muscles I was using, and whether it was
anything to do with a locked wrist, at the time, but it was hard to say,
which is why I was interested to hear the opinions of others who must have
come across the phenomenum. I am sure that you must be right, but it is
still difficult to see how such a subtle shift in muscle usage, produces
such a huge difference in the amount of effort that can be applied to the
tool.

I suppose that it's a bit like the difference between a drummer, and a
'good' drummer. You can see some thrashing away at their drums, and only
producing an average sound, whilst others seem to be putting hardly any
effort in at all, and producing a really 'big' sound. Down to the technique
of using the right muscle groups to put the force into the drumsticks, I
guess.

Arfa
 
I

isw

Jan 1, 1970
0
Arfa Daily said:
Totally off topic, but just for a bit of intellectual amusement ...

Why should the length of a screwdriver's shaft, affect the amount of torque
able to be given easily to the screw head ? This is something I learnt many
years ago as an apprentice. I have just fitted a new 'antique' bog roll
holder to one of my toilet rooms. The screws that came with it were nice
single slot chrome plated jobs to match, but were about 2" long. When I came
to drive them into the plastic wall plugs, I didn't want to use a power
driver for fear of slipping out of that slot, so I went by hand. By the time
I had got to 1.5" I was really struggling to keep the screw turning. Then I
remembered the long screwdriver trick. I have one about 18" long. The shaft
and tip and handle diameter were all near enough the same as the short
screwdriver I had just been using. Only now, the screws drive in like you're
putting them into a slab of butter. How can this be ?

If the long-shaft driver is perfectly in line with the screw, there is
no advantage. However, with a long-shaft driver, it's pretty easy to let
it lean to the side a bit, and when you do that, the amount "off to one
side" it is, gives you additional leverage -- like a short handle on a
socket wrench.

Isaac
 
N

N Cook

Jan 1, 1970
0
Arfa Daily said:
That's an interesting one Dave, and it kinda backs up what I'm saying. Even
though you would expect to get a good 'torque multiplier' effect from the
fat handle that those dumpies usually have, in fact it is actually very hard
to undo a tight screw, or get a decent tighten on one either. If I'm forced
by space to use one of them, I often finish up with a pair of Mole grips
locked on the shaft to get enough purchase.

Arfa

a call on sci-med ?
Who would ever use dumpy screwdrivers unles restricted access.
My dumpy ones have parallel flats that i've ground into the shaft to take
adjustable spanner.
 
A

Arfa Daily

Jan 1, 1970
0
isw said:
If the long-shaft driver is perfectly in line with the screw, there is
no advantage. However, with a long-shaft driver, it's pretty easy to let
it lean to the side a bit, and when you do that, the amount "off to one
side" it is, gives you additional leverage -- like a short handle on a
socket wrench.

Isaac

That's an interesting one. I'm gonna have to think on that a bit ...

Arfa
 
J

jakdedert

Jan 1, 1970
0
Arfa Daily wrote:
That's an interesting one. I'm gonna have to think on that a bit ...
It also may be useful to note that the longer shaft gives one more
options on how to hold the tool. Likely one holds the screwdriver in a
different fashion when the screw is stubborn (or simply tight). I know
that I vary my grip depending on the amount of force necessary to remove
a given fastener. A stubby can only be held in a limited number of ways.

jak
 
K

Ken G.

Jan 1, 1970
0
The longer screwdriver has a sharper more newlike tip that stays in the
screw better . The long drivers dont get used near as much as the normal
familiar size which will have a sligtly worn tip causing you to fight it
harder to keep the driver in the screw .
 
B

Bob F

Jan 1, 1970
0
I suppose that it's a bit like the difference between a drummer, and a 'good'
drummer. You can see some thrashing away at their drums, and only producing an
average sound, whilst others seem to be putting hardly any effort in at all,
and producing a really 'big' sound. Down to the technique of using the right
muscle groups to put the force into the drumsticks, I guess.

It's not force into the drumsticks. It's "pulling" the sound out with the
drumtick. As the stick hits, it is being pulled away from the head.

Bob
 
Top