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Save Time and Money: Order Metric Fasteners Online

To remain productive and profitable, manufacturers and machine shops need the right fasteners at the right time. They can’t risk running low on metric bolts, screws, and nuts, and they can’t rely on hardware stores having the fastener they need in stock. Ordering metric fasteners online with Mr. Metric’s intuitive, searchable interface offers multiple advantages over box stores. Continue reading

The Metric System: A Measure of History

Every country in the world but three – the United States, Myanmar, and Liberia – measure length, volume, and mass using the metric system, or the International System of Units (SI) as it is officially known today

Metric’s Origins

Today’s SI is the refined version of a measurement method adopted in 17th– and 18th-century Europe. The continent’s scientific, technological and industrial advances required a more precise and standardized way of collecting, analyzing, and preserving data.

But SI’s is rooted even farther back in history. Flemish mathematician Simon Stevin advocated a base-10 convention in the 16th century. It is no wonder that the French Revolution, with its violent repudiation of monarchy, would also provide the impetus to reject the arbitrary imperial system. The French developed an orderly measurement system based on logical principals:

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Choose the Right Fastener Material for Your Application

Choosing the best fastener material for a particular application requires analysis of several factors. Among these are the conditions under which the nuts, bolts, and screws will operate, their chemical and mechanical properties, their cost, and even their appearance. While no single material is right for every job, the characteristics of steel, stainless steel, brass, and nylon often make each the “right” choice for specific operations. This guide from Mr. Metric can help you choose the threaded fastener that will work best for your operation.

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“Fastener Wars”: Metric and SAE Fasteners in the Auto Industry

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?

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Metric Property Classes vs. Imperial Grades

A fastener’s strength is determined by two primary factors: 1) the material it is made from, especially the percentage of hardening carbon in the steel, and 2) the process used to create it – usually heat treatments such as tempering, galvanizing, annealing, and quenching. Treating steel fasteners to harden them necessarily reduces their ductility. Bolts, nuts, and screws can be made to fulfill tasks that require specific strengths and ductility, and identifying these properties aids contractors and manufacturers in selectig the right fastener for the job.

Metric Property Classes vs. Imperial GradesGrades and Property Classes

Metric fasteners adhere to strength ratings, or Property Classes, mandated by the International Standards Organization (ISO). Imperial, or SAE fasteners’ ratings, or Grades, are assigned by the American Society for Testing Materials (ASTM). Grades and classes are denoted by markings on the heads of externally threaded hardware and the sides or faces of internally threaded parts: Continue reading

The Metric Fastener Supplier for 3D Printers

A Mr. Metric customer, Cody Schmidt used a variety of metric fasteners to modify and upkeep his Lulzbot Taz5 3D printer. When he found a modification plan online that he wanted to implement he realized the adjustments needed for the job required very specific bolt sizes that most providers did not offer as they are hard to find or extremely rare.

Cody was very pleased when he learned that Mr. Metric carries a large range of specialty sized bolts, including the exact ones he was looking for. Cody stated:

“The most awkward size bolt I have ever used was used here too. A lonely m3x60mm bolt. But what I learned most importantly was that when reordering some parts, the shipping speeds here help big time.” Continue reading

When Can Metric Fasteners Be Reused?

Depositphotos_7100718_s-2015When 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.

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Homemade D-Bot 3D Printer Kit Assembled with Hard to Find Metric Fasteners

D-Bot Printer with fasteners 2As the revolution in desktop 3D printing for professional and educational sectors continues to grow, the demand for these printers is spreading to the consumer for home use. Individuals operating with a tight budget tend to select 3D printer kits as an entry-level option. The kits require you to assemble the printer and purchase the necessary hardware.

When researching homemade digital 3D printer kits online, you will find all sorts of information posted on blog and forum sites, as well as “how-to” videos on YouTube.  In the Thingiverse community, you can learn how to construct your own D-Bot CoreXY 3D printer. The site provides step-by-step instructions, along with the list of components and hardware needed to assemble the printer. Continue reading

Understanding & Applying Proper Torque for Metric Fasteners

Torque Explained

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.


Torque Relationship Chart


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Finding the Right Metric Nut is No Easy Task

With all of the nuts in the world, it can be hard to figure out which one is right for your assembly. To help you along with selecting the proper product for your project, here’s a brief rundown of some of the most common metric nuts and their applications.

  1. Metric All Metal Nuts
    alll metalThese general purpose nuts are commonly found on cars, farming machinery, and in metal working industries. They’re very tough, reusable, and provide a solid connection.

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