Have you ever heard anyone say, “Yeah, I glued it and nailed it!” … ?
How about this? Have you ever seen a stripped out screw? Or worse, have you ever stripped one out yourself? Rats!
Maybe you’ve pulled a rusty old drywall screw from a place where it just didn’t belong. Hmmm … No?
Okay . . . maybe I’ll get back to those, but first – a confession. Oddly enough, one of the most heavily trafficked posts on this site happens also to be one of the least developed. It’s true.
Early on, I had the kooky idea that posting simple questions might be a great way to boost audience engagement. Though pretty short lived, it did produce one of our better preforming posts – What Does the Number on Phillips Heads Screw Bits Mean? And yes, it preforms well likely because it gave me the opportunity to speak with folks at The Phillips Screw Company. Yep, that Phillips Screw and yes, they are still in business.
It’s also no lie, I’ve always been a big fan of the screw. With absolutely no scientific information to back this statement up – one to one on sheer holding power (and for the peace of mind they offer), the screw just blows other fasteners away. Why? Well, yes, maybe it is because all by itself the screw is a machine. One of the six simple machines.
Now that does not mean that every screw is the same. For example, you are not going to (or you shouldn’t) grab drywall screws and use them to mount deck boards to a deck frame. Just like you wouldn’t use upholstery nails or thumbtacks to hold down your roofing shingles, drywall screws just weren’t designed to do certain kinds of things. (Note: As self-tapping screws, though, they do make for a pretty decent general purpose fastener.)
Bottom line: Screws come in many shapes and sizes, as well as … constructions, head sizes, head types and on and on and on. There is a right one (and a wrong one) for every job. Because of that, I figured it was a good time put down a quick Guide to Common Screws by Application Type.
I know there is virtually a dizzying array of fasteners, with corresponding drive types, in various lengths and diameters, but for practicality I chose to focus only on those screws that are most prevalent, most common in common in-home applications. (To really get your geek on, I suggest instead the page – List of Screw Drives on Wikipedia.)
How to Use Screws (and other useful notes)
Really JB?! … Well, yeah.
No matter what the screw type, it can never hurt to pre-drill (with a drill bit) when you are working with wood that will ultimately present as a finished surface. This is even more important if you are within 2″ (say) of any edge, and especially if you are “toenailing” aka driving a screw on a cant. Pre-drill with a bit 1/32″ smaller than the screw’s diameter, and only to a portion of its overall resting depth.
When pre-drilling for masonry screws, it is common to drill to a depth of 1/4″ greater than the length of the screw. For more, here.
Most metal screws are designed as self-tapping and can often be identified by the screw’s tip. Pre-drilling is most applications is not recommended.
*Moxie Mouth: Flat head vs. slotted. As quoted from the Wikipedia page noted above, “Flat-head in particular can sometimes be confusing, because the term flat-head is also used to describe a screw with a flat top, designed to be installed in a countersunk hole. Such a flat-headed screw may have a slotted, cross, square recessed, or combination head, causing further confusion about the terminology.” (It is for this reason that I use the term “slotted” to describe a screw head that accepts a straight blade.)
When production, volume or quantity is not a factor, always consider driving a screw with a screwdriver instead of a mechanical driver.
If you use a mechanical drill/driver, impact driver, etc., it’s not a bad idea to acquaint yourself with specialty tools like magnetic bit holders, extension guides, and drywall dimplers. Mechanical or manual, get to know a self-centering hole punch. Most drill bit holders themselves are also 1/4″ hex drives.
When figuring screw length for joining with framing, shoot for an embedding depth of between 7/8″ & 1 1/8″. In other words, the thickness of (all of) your material, plus an inch and one eighth usually gives you the ideal screw length … usually.
Smaller diameter machines screws are often sized via common numbering like other screws, larger diameter screws come in both fractional and metric sizes and all typically mate with a nut or other piece of female threaded hardware. Great information on the sizing of machine screws, here.
Common Electrical Screws: 6-32, 8-32, 10-32
6-32 combo screws will generally be used to screw receptacles and switches into plastic and some steel box setups. Slotted 6-32 screws are used to attach cover plates for receptacles and switches. These come in a variety of painted finishes.
8-32 screws are commonly used with steel electrical and junction boxes.
10-32 screws are commonly using with mounting light fixtures. Most ground screws are also 10-32.
Great general purpose information on screw dimensions, here.
Deck screws are usually my go to choice on any miscellaneous carpentry task.
That’s it; hope it helps. Let me know if you think I might find a better way of presenting this information. And happy screwing. ~jb