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

[duncan webster 1Participant @duncanwebster1]

I’m with John Haine, you can’t get more torque at the tip than you put in via the handle.  However if you have a longer shaft of the same diameter there will be more stored energy, so when the screw starts to turn and the friction reduces it will turn further.

[egaParticipant @ega]

[File HandleParticipant @filehandle]

For a slotted screw the blade tip needs to be either parallel and a tight fit or slightly tapered and not bottom out. In both cases the blade will be in full contact with the slot sides. If this is not the case only the extremities of the blade will contact the slot sides, resulting in damage to the screw slot, blade or both. I have never tried  or seen a hollow ground screwdriver, my fear would be that you are introducing a weak point. Problems often occur with tight screws and poor fitting blades. The head of the screw that resulted in me starting this post was a slotted mushroom head with a Phillips in its center for good luck.

[old martParticipant @oldmart]

I think it was the increased size of the handle giving more torque.

[mark costello 1Participant @markcostello1]

I wonder what would be the difference in torque generated in a handle that is 1 1/8″ round verses one that is 1 1/4″ round? Enough to make a difference?

[Nicholas FarrParticipant @nicholasfarr14254]

Hi Mark, I guess it depends on the size of your hand, if it’s too big, or too small, you may not get a good grip at all.

Regards Nick.

[File HandleParticipant @filehandle]

[Phil super7Participant @philsuper7]

My Penny’s Worth, Along screw driver can be tilted further off 90 deg to the screw head, without loosing purchase thus increasing the lever length increasing torque.

[Kiwi BlokeParticipant @kiwibloke62605]

‘My Penny’s Worth, Along screw driver can be tilted further off 90 deg to the screw head, without loosing purchase thus increasing the lever length increasing torque.’

Well, if the handle orbits, rather than turns about the screwdriver’s axis, that may be true, but it’s not going to end well, as the tip slips out of the slot.

However, perhaps a long driver is beneficial for a reason not yet suggested: angular misalignment may be less, for a given  linear unintentional ‘error’ movement away from proper alignment. But I think the answer is to ensure a secure fit ‘twixt driver blade and slot. And that means having a lot of screwdrivers… I have thinned screwdriver blades on diamond laps several times (it takes ages!), in order to securely fit tiny brass woodscrews. In my experience, jewellers’ screwdrivers often benefit from having their taper made considerably shallower.

…and another thing – it used to be possible to get what was probably a stiff grease, in which was suspended diamond powder (or possibly another grit), used to produce a better ‘grip’ between blade and screw. I haven’t noticed it around recently. Is it still available / fashionable / used?

[Michael GilliganParticipant @michaelgilligan61133]

Not sulking, but I am genuinely surprised that no-one has discussed my comment about the torsion spring

#862919

It must be about sixty years ago that my Dad explained this to me, and I have never seen any reason to doubt his word.

MichaelG.

[duncan webster 1Participant @duncanwebster1]

I think you’ll find that I did in post 863312

[peak4Participant @peak4]

[Michael GilliganParticipant @michaelgilligan61133]

[Nicholas FarrParticipant @nicholasfarr14254]

Hi, I made a long flat blade screwdriver, although the resident turner where I worked, drilled a hole in one end of a piece of 1 1/2″ bright mild steel round, and knurled most of the other end for me. the shaft is a piece of 8mm hex bar, to which I shaped the blade, and case hardened it. This was for a piece of fluidizing cooling plant, the cooling was done with water being pumped through 30 or 40 or so seamless steel tubes of 3/4″ bore by 1/8″ wall thickness, which protruded out of each end of the fluidizing chamber, and were coupled to receiving and returning tanks, with reinforced rubber hose, there was at best, only about 12″ between the tanks and the chamber, with tubes being about 3″ apart inside the chamber, with about four layers with each layer offset centrally to those above. The chamber was about a meter or so wide, and every hose had two Jubilee type clips, which you can imagine were quite a job to get to in the centre section from each side, and so the shaft of my screwdriver is about 18″ or so long. Over the course of a year between shutdowns, a number of the tubes had holes worn through, due to the fluidizing action on the material being cooled, and so those tubes had to have the hoses at each end removed from the leaky ones, and folded over and clamped, until the next shutdown, as it was a major task taking off one of the tanks to change any of the tubes, and they were all replaced every year, regardless of their state. I still have that screwdriver, but I seem to have mislaid it at the moment, but I have felt the torsion spring effect using it, when undoing some tight screws.

Regards Nick.

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