We probably take fasteners—nuts and bolts—for granted until we reach into our toolbox for the right socket wrench for the engine bolt we want to remove. Do we need an SAE socket or a metric one? If we pick the wrong one, it may not work as expected. In fact, if we pick the wrong one, it may just slip around the nut or the bolt head without getting any traction at all. We also run the chance of using say an SAE bolt as a replacement with a metric-threaded nut or hole—or vice-versa.
Why is there a difference? Why have both SAE and metric nuts and bolts been used on American cars over the years? And what’s the situation now and in the future?
When looking for ways to reduce waste, cost-conscious and environmentally aware manufacturers and consumers may consider reusing metric bolts and screws. But not all bolts and screws can be safely and effectively reinstalled after being removed from an assembly or component. In fact, an unequivocal “yes” is never the answer to the question of whether a fastener can be reused. Depending on the situation, the answer is always either “no” or “it depends.”
High-strength bolts that have been pre-tensioned into their proof load range – the point at which they permanently deform and do not “snap back” when relieved from their loads – should not be reused. This is the case in many applications, as structural and other bolts used in the manufacturing, construction, and automotive industries are commonly tightened to a torque value that creates a sufficient clamp force to prevent joint failure.
Tightening a nut onto a bolt causes the bolt to stretch slightly. Much like a spring, the bolt resists this stretching, and its tendency to return to its natural state creates clamping action between, say a cylinder head and a manifold, or two pieces of sheet-metal housing.
It is critical to the component’s operation that the amount of tension created holds the parts together strongly enough to prevent their separation by outside forces such as the machine’s vibration, the load stress generated during operation, gasket creep, temperature fluctuations, and more. Too much torque, however, can stretch the fastener too much, to the point where it chips, breaks, or yields. Bolts and screws are rated by their “proof load” – how much tension they can withstand before they fail. As a rule of thumb, torque a “clamp load” (also known as “preload”) 75 percent to 90 percent of the proof load is optimal.
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The establishment of the International Organization for Standardization (ISO) is based on the need to facilitate international trade by promoting development of universal standards. Having been in place for over a decade now, the ISO 9001:2008 Certification is a universal method used by both customers and companies to control the quality of output.
It is a framework of business management ensuring continued improvements in all aspects of the business. The external assessment on a regular basis ensures maintenance of these business practices.
Whether you’re a part-time hobbyist or a seasoned mechanic, there comes a time when you have an unidentified hole, bolt, or screw. To finish your assembly, you need to know exactly what size fastener you have, or what size fastener you need. The “guess and test” method can damage the threads on the fastener and in the hole. Worse yet, you could end up with something that seems to fit, but isn’t really the right size. When that happens, mechanical failure becomes a real risk.
Fortunately, screw thread callouts are a standardized system for determining the size, thread pitch, and length of a machine screw or hole. With this information, you can quickly get all of the information you need to ensure that your fastener fits perfectly into your assembly.
Set screws are one of those smaller metric fastener components that aren’t given as much attention as they deserve.
In spite of their lack of fame, they are available in a wide variety of different fabrications. They are also used in a variety of different applications ranging from simple tasks such as installing a door knob, to more complex ones like working on a space shuttle.
Any time an object needs to be affixed to some sort of shaft, a set screw is likely to be utilized. However, given the wide variety of applications that use set screws, you want to make sure that you are using the right one for your specific application.
Chris was making a custom piece for his car and needed some uncommon hardware. He was having trouble finding a 7mm jam nut—until he came to Mr. Metric.
Not only did Chris find exactly what he was looking for, but he was also shocked when he was not forced to buy these jam nuts in large quantity. Unlike other online stores where high minimum orders were required, Chris was able to order just the pieces he needed.
One of our customers, Bryan, recently purchased new struts for his Monte Carlo. But when he received the struts, they did not come with the nuts needed to attach them properly.
Mr. Metric’s on-site staff helped Bryan find the right nuts for the job and got Bryan on the road again.
Read what Bryan had to say:
David Elliot is using Mr. Metric fasteners on his snowmobiles to improve the snow machine’s performance while also reducing the weight of the machine. These metric pipe plug screw’s tapered thread design allows for an excellent high pressure seal.
See how David is using this to his advantage:
Our first metric fastener story comes from Martin Seebach in California. Thanks for your submission, Marty!
It may not be a Christmas miracle, but Mr. Metric found a way to assist Martin when he was in need of a metric retaining ring to fix a piece of ranch equipment. Read on for the story in Marty’s words: