It’s Not So Difficult Ordering Self-Tapping Screws!
So you picked a self-tapping screw off a job site and it was just what you have been looking for but it didn’t come in a box that was labeled – it was just sitting there on the floor. What do you do? How can you ask for something when you’re not really sure what to ask for? The nice thing is that it isn’t so difficult if you know what dimensions to measure when you are asking your fastener sales representative to help you.
First describe the head. Is it a…?
- Hex Washer Head
- Hex washer head with a neoprene washer attached
- Modified Truss Head
- Oval Head
- Pan Head
- Bugle Head
- Pancake Head
There are other style heads available but these are the most common head styles that you should know. Once you can identify the head style that you are looking for, it makes things much easier.
To identify the shank size of the screw, it’s much easier if your screw is a hex head. When considering the shank size, think dress size. The smaller the number, the thinner the shank. The bigger the number, the thicker the shank.
The standard for the industry is:
• 1/4″ Hex Head = #6 or #7 or #8 shank size
• 5/16″ Hex Head = #10 or #12 shank size
• 3/8″ Hex Head = #14 shank size
Of course there always have to be exceptions just to keep things interesting.
In our case, we have needlepoint screws (aka zip screws) developed especially for the gutter industry with have high profile 1/4″ hex head but #10 washers and #10 body shanks. In the 70’s and 80’s, standard #8 screws worked fine for the gutter industry but when the quality of the wood used for homes changed, it was necessary to increase the thickness of the shanks so that the screws wouldn’t snap when hitting knots in the wood. We also added a filet underneath the head to give the screw a little extra strength.
Next, there is TPI or threads per inch to consider. As a rule of thumb, the less threads per inch, the screw is intended to be used in wood. The more TPI, the screw is meant for metal or metal studs. These are sometimes called out as ‘coarse threaded’ or ‘fine threaded’ screws. If you try and use a coarse threaded screw in metal studs or hard woods, the quality of the screw can’t really be blamed when it snaps although that happens all the time. It is simply misapplication and the more you know what screws were made for what applications, the less problems you will have when using your screws.
Now we get to the points of the screws.
Does the point look like a pencil point?
Does the point look like a drill bit tip?
There are other type points like Type 17’s used with woods and others but the two listed above are the most common.
And lastly, you should remember to state the plating that you need. Zinc plating is most common with under normal situations will last you about two years on average. Hot dipped galvanized is generally five years. But these are old school type plating. We have started stocking Dacronized®, ceramic type plating, which we normally have stocked in 500, 1000 and 1200 hour salt spray tested. They give you extra protection and even are available with the heads painted as well to match exterior applications.
When you are looking at a label on a box, the screws will generally be labeled something like “8-18×1 HWH SDS Z/P”. This would translate to #8
shank, 18 TPI by 1 inch long, hex washer head, self drilling screw (tek type point) zinc plated.
This is not everything that there is to know about self-tapping screws, zip screws and tek screws included, but it will give you a good baseline to start!
Not Just Zip Screws and Tek Screws!
Having been in the fastener industry for contractors since 1986 selling zip screws and tek screws you would think there would be nothing new to learn. Wrong! Although we specialize in screws mainly used by the Heating and Air Conditioning and Gutter industries , more and more I am hearing from OEM’S or engineers who are desperately looking for screws that don’t exist. They needs head diameter’s that are smaller so that they will fit in between narrow grooves, points that will penetrate hard plastic, then go through 30 gauge steel and then tap into stucco then into wood. And they are being used outdoors in the snow but should be rust proof but not as expensive as stainless steel. And all in the same screw! It’s a wonder I have a hair left on my head!
In years past, designer screws were a source of frustration for me because one of my contractors would pick up a screw that he really liked on a job site and then want me to locate a source for them. After many hours, maybe days, of diligent searching, I would finally find out that someone like a major hotel chain had the screws made especially for them to install the cabinets in their hotels and getting the same screws with the same dimensions was never going to happen.
Well the good news is that some manufacturers have changed their willingness to do smaller orders so that the chance of having these ‘designer screws’ manufactured is much higher now than it was in the past. Within recent months, we have been successful in procuring parts that in the past would have been impossible to supply. Of course, there are still minimums to be met but instead of having to order containers of screws in order to get the manufacturers interested, we can get away with a pallet or two. Good news for some but still not low enough for others.
Still, there are many more options available to choose from than there were 20 years ago, starting with coatings to keep screws from rusting as quickly. Take a look at our ceramic coated zip screws, available which with painted heads as well. These parts work great in areas where weather conditions are moist. We will soon be supplying needlepoint screws which are stainless steel as well as ceramic coated which will bring increased rust resistance.