View Full Version : screws heads stripping out
08-30-2005, 08:29 PM
There is no such thing as a dumb question, right?
I notice with square head and phillips/frearson head screws that the bit wears out after a while, and the screw heads strip out with more and more frequency. Is there something I'm doing wrong, or is this something everybody tolerates?
It's gotten so that I reach for the hand screw driver more and more often, and the arthritis is really starting to act up.
Some are better quality than others but they all wear out after a while. Fortunately they are inexpensive so when they start to jump out of the screws when they shouldn't just toss them and switch to a new one.
The more often they slip, the faster they wear. If you have an adjustable clutch on the driver the lowest practical setting helps.
08-30-2005, 09:25 PM
I've always wondered why, but, yea, they do wear out. That's why there's always a bucket of them on the counter at the hardware store! You'd think that they'd make a bit that was harder. Maybe there's some reason we don't know. Maybe they've decided with the powered drivers, it's better to strip the bit than the screw slot. I dunno... interesting existential question, that.
08-30-2005, 09:36 PM
A little modification helps. Grind off a little of the point of the bit, the bit should bottom on the sides of the slot, not on the point. Most of the bits phillips and square need this modification to get better results. The other very important thing is make sure the driver is absolutely in line with the centerline of the screw and also hold some down pressure while driving. If the bit bouces out of the screw when driving you are not holding the driver square, which indicates you took lessons from that Norm guy on the TV program.
Peter Malcolm Jardine
08-30-2005, 10:09 PM
I buy robertson and philips bits by the box. 25 of each. :D I drive a lot of robertson deck screws.
Philips don't power drive worth a S&*T anyway. both the bit and the screw suffer
08-30-2005, 10:14 PM
For square drive screws I find that the better quality bits from McFeelys last quite a while, but even they wear out with time...
For phillips make sure you are using the right size driver for the size of the screw. If you use the wrong size it may appear to fit but won't seat well and thus will wear out much faster...
08-30-2005, 10:43 PM
Funny thing about Phillips screws and drivers; they were originally designed to "cam out", or strip, as we call it now. "Camming out" kept a worker from overdriving the screw and breaking it, or breaking something else. The Frearson modification of modern times reduces this tendency, but it still happens. Happens with square drives too once you've worn the driver just a little bit.
08-30-2005, 11:22 PM
The best bit is the grabber bits that come with the grabber drywall screws.Also the screws are perfectly matched with the bits hence the inclusion of the bit with the case of screws.When hanging sheetrock,it wasn't uncommon to drive nearly 200,000 screws with the same bit.There is little barbs on the bits that keep them bottomed out in the screws.
[ 08-30-2005, 11:23 PM: Message edited by: pipefitter ]
08-30-2005, 11:36 PM
Many steel parts - of machines, and our tools - are heat treated. This is done for various reasons: to increase the part's overall strength characteristics, such as tensile strength: A grade 5 bolt typically begins life as medium carbon steel- .03 to .04 of one percent carbon and various other alloys. It's initial tensile strength is somewhere around 40,000 to 50,000 pounds per square inch. Through the hardening and tempering processes, this can be increased by a factor of 3 to 5 times- 120,000 to 250,000 psi.
All other mechanical characteristics of the bolt increase as well- hardness- and sadly, brittleness. It is the tempering process, along with the steel's chemical makeup that determines the final outcome. All else being equal, if the tempering temperature is too low, say 350 F, the bolt will retain both a high level of strength, but also be very brittle, and will easily fracture. Too high, say 800 F, and the bolt almost returns to it's original state. Since many of the screws we use today (like the ever present Drywall Screw) are also heat treated, the bits you are using might not be much harder than the screws themselves! Quality screwdriver bits will have the correct chemical makeup, and be properly heat treated. Cheap ones may have neither.
Another tip: Don't get a retired teacher started!
08-31-2005, 02:27 AM
There are several "square drive" type screw heads and they all look very similar, but are actually all slightly different, for a start it's important to have the correct style bit for the screw and the correct size. Sorry if that sounds too obvious but that's by far the most common problem I see.
I prefer to use the hard (usually gold coloured) diamond encrusted bits, the tiny diamonds give the bit some grip and they definitely seem to slip less than standard ones.
Decent quality screws help a lot too, I notice cheap ones cam out easier than the more expensive ones.
08-31-2005, 01:31 PM
In my experience with Robertson-drive screws(aka "square-drive") is that the best drivers, regardless of the brand of screw used, are, oddly enough,...
genuine Robertson<sup>®</sup> brand drivers.
09-02-2005, 12:19 AM
Yankee screwdrivers rule. I'm refastening my friendship with one. Lube the screws with linseed oil, zip them right in. removing the old ones however.....gives me arthritis too. good luck
09-02-2005, 11:33 AM
I was wondering when someone was going to say that.
I don't drive screws with an electric tool much. As noted, they strip too often.
I get better results using a robertson driver chucked in a "speed wrench" which is a socket driver in the shape of a brace and bit. Sure it's strictly manual, but it's fast enough and there is perfect control of torsion.
I also have a manual driver which is in the shape of a pistol. You squeeze the trigger and it drives the screw. Then, when it's too hard to drive, you use the whole pistol as a ratcheting driver. I'll have to go look up the name on it.... it's my favourite screwdriver.
MInd you, I'm not building decks, or driving a thousand screws a day, in which case I'd use an electric driver too.
09-02-2005, 01:12 PM
on hardened bits...
I recently bought a bunch of McFeely's No-co-rode promax screws and the slightly undersized #2 bits to go with them for rebuilding the deck at my house. Love 'em. However, when I decided that I wanted to relocate a couple of the longer screws (3 3/8") after they'd been in a day or two, I found that the bit was too brittle and simply broke instead of extracting the screw. After this happened on the first 3 of 4 attempts (different screws in different places) I simply decided that they are all just fine right where they are.
Thus, perhaps the reason most bits are not hardened is that they become too brittle.
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