How do you identify different types of screw heads

[Rodney]

I have some bad hard disk drives I want to take apart to salvage the magnets out of. The screw heads are not typical and do not seem to be Torks. One brand is similar to a 4 cornered socket screw and another is like a 5 star shaped depression. Do these have a name or are they used only by that manufacturer? Is there a source of names versus shape available?

[Janitor Tzap]

I don't know the exact name either.
But these security screws, and bolts.
Take special bits or tools to remove them.
A set like these

Check tool suppliers like MCM or a local electronics tool supplier for the right bit you need.


Signed: Janitor Tzap

[dacflyer]

harbor freight also sells a huge security bit set too, all kinds i never seen..
like 3 point phillips.
one bit fits in a screw head with 2 holes in it..
have a look if theres a store near you..

[Dean Huster]

I've already done some research on drive types. Here's a couple of sites I've found:

http://www.sizes.com/tools/screw_drive.htm
http://www.wiha.com/england/Information ... head-types

Dean

[MrAl]

Hi Dean,


Thanks for posting that...very interesting. I was beginning to think that some of these screw heads
i was finding were screwed in by an alien from another solar system or something (chuckle)

[Janitor Tzap]

Nice find there Dean.

Thou....
I have come across some very specialized security bits.
They look like rounded rivets heads.
But are designed for assembling stalls in rest rooms.

The tool used is a hard rubber molded like cup on the end of a shaft.
This fits the screw head and uses friction to install or remove the screw.
If I find a picture, I'll post it.


Signed: Janitor Tzap

[Dean Huster]

Would that be the standard "slotted" head that you can drive in clockwise but the driver ramps out when you go counterclockwise? Wait, you said absolutely smooth, like you were looking at the head of a carriage bolt?

It's interesting how many uninformed folks look at a cross-slot screw head and immediately call it a Phillips head. There's maybe eight or nine variants including Phillips, Reed & Prince, Frearson Cross-slot, Pozidriv and a couple of improved Pozidriv and combination heads that all look Phillipy, but aren't.

Dean

[gerty]

We had some here that we got by accident, they were smooth but slightly out of round.
The accompanying socket looked like it had a small round recess, but if you used it to drive a screw it worked quite well.

[Engineer1138]

Brute force approach if patience fails:

Hand drill + screw remover bit!
Actually, if you really want to go brute force, forget the screw remover and just drill the entire screw out of the casting.

Ah, the memories of last weekend spent under my truck with an angle grinder and a cutoff wheel and facefuls of rusty exhaust!

[haklesup]

Since your only interested in salvaging the magnets, you might find it easier to drill or grind the heads off rather than investing in a bunch of security screw drivers. Some security screws are somewhat standard and you can get drivers for them but others are completely custom made for a particualr OEM and supplied with matching bits. Sometimes you can modify a standard driver of some sort with a grinder.

Now if you said repair then you would need a proper driver for disassembly/reassembly

[mthornton]

4 cornered socket screw sounds like a basic robertson head screw. Very common in Canada & UK mfrd products. Commonly used in 4 basic head sizes.
http://en.wikipedia.org/wiki/Robertson_screwdriver

Mr. Robertson was a Canadian electrician who wanted a screw that would not slip, and would hold itself onto the end of a screwdriver.

My American ex-Father-in-law expressed envy over the superior functionality, as Robertson screws are not readily available in the USA. So I sent him a set of drivers, enclosed in a small wooden box, screwed together with various different sizes of Robertson screws. (I'm mean)

The reason they are not used in the USA is a liscensing disagreement stretching back many decades. Canadians wonder how Yankies can build anything without them.

[Janitor Tzap]

4 cornered socket screw sounds like a basic robertson head screw. Very common in Canada & UK mfrd products. Commonly used in 4 basic head sizes.
http://en.wikipedia.org/wiki/Robertson_screwdriver

Mr. Robertson was a Canadian electrician who wanted a screw that would not slip, and would hold itself onto the end of a screwdriver.

My American ex-Father-in-law expressed envy over the superior functionality, as Robertson screws are not readily available in the USA. So I sent him a set of drivers, enclosed in a small wooden box, screwed together with various different sizes of Robertson screws. (I'm mean)

The reason they are not used in the USA is a liscensing disagreement stretching back many decades. Canadians wonder how Yankies can build anything without them.

Those screws are very popular with the builders in my area of the country.{MN/USA}
And you can get them easily, at the local hardware stores, or building supply stores.
Thou, some builders have been using the slotted hex head screws as well.
Because the heads don't get torn up as easily as a Philips head or Slotted head screw.


Signed: Janitor Tzap

[Dean Huster]

Square-drive screws have been in the U.S. for a long time, just not as the Robertson, which has Canadian origins as mentioned. In the U.S., we had the Scrulox drive, a square-drive that was patented by Stanley, as I recall. The difference is that the Scrulox driver has parallel sides while the Robertson has a slightly tapered driver. Now how the heads of the screws compare, I don't know. If the Robertson screw head is tapered like the driver, I don't see how it'd hold onto the driver any better than the Scrulox. On the other hand, if the screw head has parallel sides, then it makes sense that the driver would jam into the head -- but the mating driving surfaces would have less area and be subject to easier cam-out or stripping.

I just finished repairing a customer's deck (it used treated 2x4s for decking material vs. the 5/4 material more commonly used) and they had used stainless steel screws (square-drive) originally. They didn't rust, that's for sure, but what a worthless screw!! Stainless steel is soft and I spent more of my time using screw-removal bits and pliers to get screws out. Some of them were actually clinched over like nails. Needless to say, I used ceramic-coated steel screws for replacement.

I also like Torx heads for deck screws.

Dean

[Bob Scott]

...if the screw head has parallel sides, then it makes sense that the driver would jam into the head -- but the mating driving surfaces would have less area and be subject to easier cam-out or stripping.

Robertson drivers have a slightly curved taper, but the angle is so small that cam-out never happens. The friction between the screw head and the driver locks the driver in. I used to cut the shaft off a Robertson driver and install it into my drill chuck. Works great, but there's no clutch and when the screw head is flush, the drill does not stop immediately. The momentum of the drill always sinks the head too far into the wood. I must get myself one of those new fangled electric drivers with a clutch.

I just finished repairing a customer's deck (it used treated 2x4s for decking material vs. the 5/4 material more commonly used) and they had used stainless steel screws (square-drive) originally. They didn't rust, that's for sure, but what a worthless screw!! Stainless steel is soft and I spent more of my time using screw-removal bits and pliers to get screws out. Some of them were actually clinched over like nails. Needless to say, I used ceramic-coated steel screws for replacement.

From what I read on a google search for "ceramic screw", stainless screws need a predrilled hole, but stainless is more popular than ceramic. See link:
http://ths.gardenweb.com/forums/load/po ... 30912.html

I've never seen a ceramic coated screw. Must be something new. I hope the next invention will be stainless steel coated screws. Bent over screws? He had the skill levels of the man who originally built my deck (over living space) who installed face boards after installing an epoxy-glass deck surface. One of the face board nails, just one, poked through the top surface of the deck. One little puncture was enough to start leaking rain water just enough to rot out a giant section of the plywood floor 20 years later.

Bob

[Dean Huster]

Bob, if you go to HD or Lowe's, I think that about all you'll find for deck screws (cement board screws are often used for deck screws) are ceramic coated. They're usually either gray or OD green in color. A deck would get pretty expensive if you had to predrill all the screw holes. That takes a lot of time -- and bits. Technically, you'd want to countersink the holes as well to minimize splitting. But treated deck wood is so danged soft that you can't help but bury the screw heads without realizing it.

Dean