How To Determine If The Fasteners You Need Are Actually Metric

Here in the U.S., it is generally taken for granted that everything is standard measurement. People are oddly surprised when they encounter a need for anything measured in metric. If you are trying to fix machinery, and you need more fasteners, you may need metric fasteners instead of standard. Here are some ways to determine if the fasteners you need are actually metric, and not standard measurements.

The Fit Is Not Perfect

Let's say that you are trying to fit some screws to a hole to hold two components together. The two sizes of standard screws that you have do not quite seem to fit. One is too small and just slips and flip-flops in the hole, while the other cannot make it through. Even though these two standard screws are literally a single size apart, neither one works in the hole through which you are trying to fit the screws. This is a sure sign that what you need is metric because metric screws will fit this odd-sized hole perfectly. Look for the metric screw that falls right between the sizes of the two standard screws you have.

The Thread Is Not Perfect

People who do not know a lot about screws are most surprised to learn that not only are the diameters of metric screws different from the diameters of standard screws, but the thread gauges are also different. This is the spacing in between the winding threads of screws, nuts, and bolts. The easiest way to test this is to use thread gauges, which are sets of tools inserted into nuts or which measure the thread spacing on bolts and screws. If the metric gauges fit, you have metric fasteners. If the standard gauges fit, you have standard fasteners. When inserting these fasteners through holes, the holes are cut a little differently too, with a sort of slanted "lip" for holes requiring metric fasteners.

The Machinery or Product Is Made in Another Country Where Metric Is the Standard

When a product or piece of machinery is manufactured entirely in another country where metric is the widely used form of measurement, you should try metric fasteners first. You may have better luck finding exactly the right fasteners for what you need rather than have to go through a trial and error process. If the machinery or product is made in the U.S., you can bet that standard measurement is the right choice in fasteners.