No matter which type of screwdriver you use, the most common failure mode when trying to loosen over-tightened screws is for the screwdriver blade to slip out of the screwhead, Usually, in doing so, it also damages the slot in the screwhead, so that subsequent attempts are even more likely to fail.
I think screwdrivers (of any design) would work better if their tips were coated with a very fine abrasive (industrial diamond would be the best bet). This would cause the screwdriver to bind very tightly against the sides of the screw's slot, and make it much less likely to slip out.-- MaxwellBuchanan, Mar 08 2015 Diamond Coated Screwdriver Bits http://www.wihatool...700_diamondbits.htm [bs0u0155, Mar 08 2015] Triangle wedge screws http://www.chakwame...uct-detail-338.htmlIn terms of geometry's association with force-application, for driving a screw, this may be the best. [Vernon, Mar 09 2015] Here's a quite nice set from Amazon http://www.amazon.c...river/dp/B0041SVZRE [zen_tom, Mar 09 2015] I suspect that the most common cause of your most common failure mode is using the wrong size screwdriver.-- 21 Quest, Mar 08 2015 They've been around for a while, <link. it's actually best to consider screwdriver bits as consumables, particularly with power tools. In that case, the economics favour titanium nitride or tungsten carbide.-- bs0u0155, Mar 08 2015 oh, and what 21 said. My misfortune with screws/screwdrivers disappeared in a roughly inversely proportional manner to my ability to recognize sizing.
I once did some maintenance on some German GR1 Tornados. The offset cross head things they have might as well just be rivets. At least 80% needed stud extractors or drilling out. I wouldn't have minded if they were titanium, at least then there would have been a reason.-- bs0u0155, Mar 08 2015 Why not just get rid of outdated flat and phillips type screw heads in favour of cap head or torx? Much more transmissable torque before gouging, and it forces you to use the right size bit - failure of which is why most screw heads come apart.
If you want to do up and undo flat and phillips head screws over and again you need proper hollow ground flat head screwdriver bits in a number of sizes, and a complete set of phillips head bits. Might as well have a allen or torx set instead and do the job proper like.-- Custardguts, Mar 09 2015 I think the movement to hex/torx is well underway. My recent forays into the innards of a new Macbook have taught me that although the conversion is well underway, the super small screws are all inevitably still phillips. I'm tempted to say it's because a countersunk screw head has a profile which closely fits that of a pointy screwdriver.-- bs0u0155, Mar 09 2015 If it is mission critical, any driver that works that replaces the one correct one missing from the new set gets my smile.-- wjt, Mar 09 2015 I'd like to add my vote in favour of the world utilising Robertson bits (square). They grip well enough to the bit you can put the screw onto the driver first then move into position and grab so well you're more likely to twist the screw head off than slip. Colour coded too. (good idea though) [+]-- AusCan531, Mar 09 2015 Not the cocktail then?-- xenzag, Mar 09 2015 //They've been around for a while, <link>.//
Ah. Well, then, that's OK.
As for choosing the right size screwdriver, or various head geometries - yes, but better grip is still helpful.-- MaxwellBuchanan, Mar 09 2015 If the tips were circular and completely smoothly-polished, the number of contact points could be infinite. Clearly that's the design of choice...-- RayfordSteele, Mar 09 2015 But...-- MaxwellBuchanan, Mar 09 2015 //circular and completely smoothly-polished//
That works actually, drill a nice neat hole down the middle of a stripped bolt, bash in some mild steel rod for a good interference fit (bonus points for dipping the rod in LN2 first) then either bend it over or grind a pair of flats on the rod for the biggest adjustable spanner you have.-- bs0u0155, Mar 09 2015 I like that last. The LN2 is nifty. You could use dry ice in a pinch.-- bungston, Mar 09 2015 Yeah, and flat headed screwdrivers can chisel a new slot on a screw which matches the screwdriver exactly...-- Ling, Mar 09 2015 //flat headed screwdrivers can chisel a new slot on a screw which matches the screwdriver exactly//
well now, so you're the apprentice that was walloping the back of a screwdriver with the 5lb lump hammer? exactly how far into that 316 stainless screw did you get before you split the screwdriver handle by pounding it down the shaft? hmm?
Now, correct procedure with a protruding head is to hacksaw (Dremmel is an acceptable answer) a slot into it. Should there be no protruding head, or you've already destroyed the head, move onto the tungsten screw extractors. That driver's coming out of your wages.-- bs0u0155, Mar 10 2015 Do your drivers beat out a rhythm ?
Johnny B. Goode
He use to carry his guitar in a gunny sack And sit beneath the trees by the railroad track. Oh, the engineers used to see him sitting in the shade, Playing to the rhythm that the drivers made. People passing by would stop and say Oh my that little country boy could play-- popbottle, Mar 10 2015 Some screwdrivers are seemingly made to accept a large hammer blow from the end. These are best to keep very apart from the electrical screwdrivers that are less conductive. Yes, I'm also the apprentice that works on live connections.-- Ling, Mar 10 2015 Reading the title made me think it was going to be a really dumb idea. Change to "diamond-tipped"?-- Voice, Mar 10 2015 If ease of disassembly is the goal, the LN2 provides the best answer. Simply dip the entire apparatus that needs taken apart or pour the LN2 over it, and then go at it with a mallet.-- RayfordSteele, Mar 10 2015 I have had luck extracting a wedged penny from the disposal using dry ice. I like the idea of unwedging metal by supercooling it.
A problem with LN2 is that it slops all around: a waste of coolth. Even the stuff that hits the metal of interest stays only for a moment.
hmm hmm hmm - inspiration!-- bungston, Mar 10 2015 Gelled liquid nitrogen?-- notexactly, Mar 11 2015 [notexactly], that is not such a stupid idea. I'm not sure what would remain gel-like at LN2 temperatures, but there must be something.-- MaxwellBuchanan, Mar 11 2015 //what would remain gel-like at LN2 temperatures// - Maybe just an ice slush of something else that melts at somewhere above N2 evaporation temperature?-- Custardguts, Mar 11 2015 random, halfbakery