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.

[Grindstone Cowboy]

On Grindstone Cowboy Said:

On Kiwi Bloke Said:

….. The pukka turnscrew has a shallow-tapered blade, the idea being that it doesn’t quite bottom, but wedges tightly into the slot. It’s surprisingly confidence-enhancing to use such a bladed turnscrew.

Yes, traditional turnscrews don’t have the “hollow-ground” end, that’s something which I suspect emanates from the USA – and they are very good for their purpose – but not for old English guns.

Rob

I have a couple of Marples cabinet screwdrivers with “SKIDPROOF” cross-ground points which have served me well for many years. TBH, I’m not sure what their geometry should be as they have been re-ground from time to time. I think the idea is that the tip is parallel in thickness where it enters the slot and, therefore, bottoms in it rather than wedging.

[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.

[mark costello 1]

On mark costello 1 Said:

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?

11%

[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.

[Author]

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