Half a croissant, on a plate, with a sign in front of it saying '50c'
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Power screwdrivers

Problem with old plain-slot screws
  [vote for,

OK so many handyman and all tradespersons these days working on new construction, use self-starting screws and designer drivers that they fit snugly into.

But there are older constructions everywhere held together with the old plain-slot screws.

A plain-blade driver head gets them turning out well enough but keeps slipping off annoyingly when you’re trying to drive them in.

I’m too mean to replace my tin of old screws with the new ones so I reckon this would work - ask a jobbing engineer to grind a plain blade driver into a concave shape - like this C only slightly shallower, leaving two re-hardened points to dig into the bottom of the slot of the screw and keep the blade in place.

The foregoing is dream-stuff of course; I haven’t been safe near tools for years and the grandson who does odd jobs for me, does so at warp-speed and departs similarly so he won’t have to listen to my witterings.

rayfo, May 04 2001

Robertson Screws explained http://www.sachys-r...on.com.au/home.html
Also, why they are hard to find in some countries. [gen1000, May 04 2001, last modified Oct 04 2004]


       Tell me more about these self-starting screws and designer drivers?   

       I gather by "plain-blade driver" you mean what I would call a "flat-head screwdriver". Would the indentations you describe really dig in to the screw? Wouldn't that raise the level of the blade, reduce the amount of contact, and make it more likely to break or slip?   

       Here's one idea a picture would help, I think.
egnor, May 04 2001

       I've seen flat-head screwdrivers with a sort of ridged surface which I've speculated might be to help keep the driver fromslipping out of the slot...
wiml, May 04 2001

       rayfo, you're right. Standard straight-bit drivers do tend to jump the slot. If your driver is of real tool steel then I think your idea of the hollow-ground bit would work. Most of my screwdrivers seem to be too soft to hold a finely-shaped edge--I think the spot where your custom grind removes a little metal just above the end would probably bend or round off too easily.   

       egnor: self-starting screws: I often use deck screws that take a square driver roughly 2 mm on a side. They're self-tapping in wood and plaster, and really made to be driven with an electric screwdriver or a drill motor. The same screws come in Phillips cross-top. Torx multi-pointed (I think there are 6 facets--I never counted) screws are also available but I've seen the Torx top mostly on bolts fastening PC cases (Compaq) and the like.
Dog Ed, May 04 2001

       I agree with UnaBubba - with straight slot screws, the quality of your tools is very important. The difference between using a driver head which fits the screw and one which nearly fits is huge in terms of how quickly your tools wear out and in the effort needed to turn the screw.
hippo, May 04 2001

       I have, in fact, seen this very idea before in an OLD 'Popular Mechanics' <I think. It was 30 years old when I saw it and that was 20 years ago...>.   

       Phillips screws were indeed designed to be used with power drivers because the flat ones kept falling out and adding new and exciting design features...
StarChaser, May 05 2001

       Uh, Peter, I'll politely (and only politely because you're... oh wait.)   

       Damn it, Peter, read the idea!   

       "But there are older constructions everywhere held together with the old plain-slot screws." The point is to help people deal with this "legacy".
egnor, May 05 2001

       <obsolete>The "mechanic's screwdriver" that had a spring and a pair of tongs at the blade for hanging out screws. I think it was replaced by magntized tips, and later by 'drivers' with square and other blade shapes.</obsolete>

rayfo: Try grinding a spur from opposite, drive angle faces of the blade. These should imbed themselves upon application of torque, so to give that mite of purchase needed to push those pups on in. Use the mirror image to make a bit for backing screws out. To busted knuckles &+
reensure, May 05 2001

       Re: getting screws out of wood. Method 1 - I have a toola bit like a corkscrew, but with a blade like a screw with a very fine pitch, made of extremely hard steel and which screws in anticlockwise. You drill a small pilot hole in the screw you want to remove, screw this tool in (anticlockwise). It tightens against the inside of the pilot hole and you carry on to remove the screw.
Method 2 - I once had 2 steel screws shear when attaching the base of a table to a solid Maple top, leaving about 1/4" of metal sticking out. I clamped on a Mole wrench (what a tool!) as tight as I could and unwound the screws.
hippo, May 10 2001

       Well, yes and no. I knew about the above devices and procedures, but that's how to remove a broken screw, not how to insert a flat-headed one easier.
StarChaser, May 10 2001

       If I were stranded on a desert island and was given only one tool of my choosing with which to build an acoustic guitar out of indigenous underbrush, I would choose Vice Grips. What a tool, indeed.   

       I've a powered, tabletop grindstone, and a couple of flathead screwdrivers. I can't imagine that it'd be too difficult to do exactly what rayfo describes. It'd take just a steady hand, a uniform stone, good eyes, and lots of light.
absterge, May 10 2001


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