Have you ever ever questioned why carpenters get to work with 1/2″ drywall however metallic fabricators need to specify sheet metallic thickness by way of gauge? It’s a reputable query that a whole lot of people who’re new to metallic fabrication wrestle with. To make issues extra complicated, the vary of gauge sizes works reverse of standard logic, with bigger numerical values representing thinner materials and vice versa. And if that weren’t sufficient, the precise measured thickness for a given gauge of sheet metallic varies relying on the kind of materials it’s.
So how did we get right here and why are we nonetheless utilizing this method?
The “how” a part of the query begins on the peak of the American Industrial Revolution. In 1893, the U.S. Code was amended to incorporate Title 15 Chapter 6 Sub-Chapter III Part 206, which established a “customary gauge for sheet and plate iron and metal” to standardize the burden of supplies weight for the needs of tax assortment. Previous to this, completely different producers used their very own measuring methods to promote their supplies, resulting in inconsistencies available in the market. This method, often called the U.S. Normal Gauge, was similar to the American Wire Gauge (AWG) developed by Brown & Sharpe in 1857, however particular to the character of sheet metallic as an alternative of single-strand spherical wire.
The code outlined a 45-step chart of fabric thicknesses from 1/2” (0000000 or “7 aught”) to 1/160” (38-gauge) for these. The completely different gauges on the chart represented (not less than on some stage) the variety of discount steps, or attracts, required to squeeze the fabric into ever thinner sheets. Consider it just like the variety of passes a rolling pin makes to work a lump of dough into a skinny pie crust. That’s why 20-gauge metal is thinner than, say, 10-gauge.
Consequently, for every “gauge” there’s a constant weight for a given sq. inch or sq. foot of a given materials, no matter whose mill produces it. That’s additionally why completely different supplies have their very own gauge specs. For those who measure a bit of 14-gauge carbon metal with a micrometer, will probably be 0.747” thick, whereas a bit of 14-gauge stainless-steel will measure out to 0.751”. That’s as a result of carbon metal has better density than stainless. Likewise sheet aluminum, brass, and copper all have their very own gauge charts as nicely.
So on this age of laser measurements and digital micrometers, why can we nonetheless use the U.S. Normal Gauge in any respect? The reply largely comes right down to familiarity. After 130 years of standardization, it’s what the business is aware of and has constructed its tooling for. Nonetheless, some international locations use nominal measurements (usually in metric figures) for each sheet metallic and wire, whereas others have adopted their very own requirements over time.
For the reason that system apparently isn’t damaged, we don’t count on it to alter anytime quickly. What’s necessary is that you just perceive learn to a sheet metallic gauge and that you understand what materials you’re working with.
