When you need a bolt, it’s tempting to find whatever’s around that meets the size specifications you need. But so much more goes into choosing the right bolt for the job. There are other considerations, too, like how well a bolt grips and how it distributes a load. There are many different types of bolts, screws and other fasteners today because there are different requirements for different types of jobs.
When you have a specific job at hand and you need dependable bolts, you have many decisions to make. Perhaps the most important decision is whether you need a partially or fully threaded bolt. To help you gain more insight and make the best possible decision for any project, here's a look at full thread vs. partial thread screws.
Partial Thread Bolts
Partial thread bolts offer an area just below the head that is completely free of threading. They are called "partial" thread bolts because of the part that has no threading. This non-thread portion of a bolt will vary in length depending on the bolt's application.
Why choose a partial thread bolt? Partial thread bolts are best for resistance and alignment. When you have a project that requires a lot of force to hold an object in place, a partially threaded bolt delivers the resistance needed. The non-threaded portion is also known as “grip length,” and this grip length includes no weak spots that can lead to a shear.
When using partially threaded bolts, they can be driven into holes that are threaded or they can be used as part of bolt-through applications along with a nut and washer on the end with threads.
Full Thread Bolts
As you might have guessed, fully threaded bolts have no grip length or thread-free portion. The threads run from just under the head all the way to the tip.
Why choose a fully threaded bolt? If you’re most interested in grip strength and less interested in alignment and shear strength, a fully threaded bolt is going to be your best option. Once mounted, a full thread bolt spreads pressure along its entire length, with the greatest holding pressure placed on the head where it meets the material to which it is fastened.
What Bolts Are Used For
No one type of bolt is used more than another. Rather, the bolt you should select is all about the type of fastening you need.
Choose partially threaded bolts for projects that demand extreme holding force. Partial thread bolts are often used for motor mounts, alternators and other automotive fastening, as well as water pumps. In these types of applications, precision is vital and the grip length of the bolt delivers the alignment that’s needed. During tightening, the grip length is pulled tight into the hole, yanked in by the threads that are exposed on the other side of the hold. The resulting force is what’s needed to hold motor mounts securely.
Choose fully threaded bolts for applications that need more grip strength than holding force. If you would use partially threaded bolts for automotive fastenings, like motor mounts and alternators, use full thread bolts for automotive fastening like body panels. Body panels do not require the same amount of holding force that motor mounts demand, but they do need a stable grip. A partially threaded bolt's holding force is all at the threaded tip, whereas a fully threaded bolt extends the holding force across the full shaft.
Choosing the Right Bolt for the Job
As mentioned, you face a number of choices and options when searching for the right bolt for your next project. But when it comes to choosing full thread vs. partial thread screws, consider whether you need maximum grip strength or maximum protection against shear. If you need grip strength, find the right full thread bolt that’s made of the material you need. If you’re more concerned about shear, choose a partially threaded bolt that’s going to help protect against it.
You’ll find that different partially threaded bolts have different grip lengths, so consider how long you need a grip length to be before making your purchase.
About FMW Fasteners
At FMW Fasteners, we serve both professionals and do-it-yourself enthusiasts who need high-quality materials to create outstanding results with their projects. You’ll find a huge selection of both fully and partially threaded bolts as well as all of the other fasteners you might need for the job at hand. You can order in the exact amount you need rather than settling for a random bulk quantity.
You enjoy everyday low pricing at FMW Fasteners as well as fast and affordable shipping. We even offer free shipping on orders of $25 or more. You can also send back what you don’t want or need at any time, with no expiration.
Have questions about full thread vs. partial head screws? We're always here to help. Not only will you find the best selection of materials at FMW Fasteners, but you'll also find a customer service team that's fully focused on helping you find just what you need. Everything we do, from our selection to our ordering process to our customer service, is designed to meet the needs of professionals and do-it-yourself enthusiasts who want the best materials so they can deliver the best results.
Browse our selection of partially and fully threaded bolts today.