Pity the poor fastener!

You drop a screw and it rolls under the sofa, and now you are faced with getting a hernia or getting a replacement screw. No problem you think. You go to your trusty collection of assorted screws, only to discover that that was the last of the “special” screws that you need to mount your new hard drive! Arrrgggghhh! Do you have to go to a special computer or electronics store, or can you get the right screws at the corner hardware store? Well, you cannot very well go into a hardware store and ask for hard drive mounting screws, you have to speak the right hardware language, and that is what this article will help you conquer! And a hardware store is about the only place where you can talk about screws in polite company. The poor little fastener that holds our computers together has gotten a bad alternate meaning.

Name that material!

Fasteners come in many different materials, and you may want an assortment. Since the computer case is made of aluminum, you would not want to use an aluminum screw, even if they were widely available. Softer materials like aluminum and brass tend to fuse too easily if you tighten them together. Then you will never be able to get them apart, unless you drill the screw out. Stainless steel makes a good choice, but some of the milder stainless steel can pick up a magnetic charge, which can disrupt tiny electrical signals. There are also screws made out of plastic or Teflon, and these are excellent to use as things like motherboard standoffs, where you want to make sure that there is no path for an electric signal between the board and the bottom of the case.

Hanging by a thread!

The biggest problem in getting the right screw is getting the right size in combination with the right thread. To make matters worse, the really small screws are given a number code, and then they start going by fractions of an inch. The good news for us is that the screws that hold our computers together never get that big, so we stay in the realm of the numbered screws. The numbering system used is the drill bit number that you would use if you were making a regular hole that the screw would fit through. For example, the ever-elusive screw for mounting the hard drive? It fits through a #6 drill hole, so it is a #6 screw. Now all I have to identify is the number of threads per inch (tpi), and I will be ready to talk to the hardware store clerk.

In the United States, we have three thread types defined as National Standard, National Coarse, and National Fine. The National Coarse thread had the fewest threads per inch, and tends to be used for heavier objects because the individual threads are stronger. The National Fine thread screws are usually used for more delicate work, and are hard to work with, because the threads get damaged (“stripped”) easily. The National Standard is suitable for most jobs, and is the easiest to work with.

The number of threads per inch will vary, even in the same type, depending on the size of the screw. For example, our #6 screw with 36 tpi, is a National Standard screw. A #8 screw with the same 36 tpi, would be a National Fine screw. It makes sense that as the screw gets larger, it will be holding a larger/heavier object, so you would want sturdier threads. The fewer threads, the more defined and stronger the individual threads are.

Standard Computer Hardware
Okay, so what screws do I actually need to assemble my computer?

The good news is that as far as I can tell, most computers use the same standard screws, and the major manufacturers have not bothered to get proprietary down far enough to affect the screws you need to have on hand. So the list goes as follows:

Motherboard mounting:1/8-44 NF The screw that is inserted into the standoff. Usually is Stainless Steel

Do yourself a favor! It is very difficult to tell by eye whether a screw is a fine thread or a standard thread, so for about $8 USD, you can get a very nice thread gage, like the one that I use from General Hardware MFG. Co. Inc. You can get them in most hardware stores, and they work as a nice drill gage also.

To Top it Off The one other thing the hardware clerk is going to ask you is what kind of a head is on the screw. The standard head types are:
Flathead (not used in any computers that I have seen) Roundhead (rarely used in computers) Panhead (slightly rounded head, sorry I could only find a picture of a sheet metal screw) Hexhead. In a computer screw, we would want the head to have a Phillips slot.

When the clerk asks what length, a quarter inch long is the right length for all of our purposes.

The Humble Fastener that holds it all together

Without these little easy to lose screws, we could not assemble the mighty computers and servers we so love to play with. The good news is, you don’t need a huge assortment of screws to get by, just make sure you keep the hard drive screws separate from the others, and you will have a much easier time the next time you are assembling a new masterpiece of computing engineering.