Recent discussion on aluminium blanks got me thinking about gage as a unit of measure. I had always assumed 12ga was 1/12" and 16ga was 1/16", and so on; thats fairly close with some gages, but its wrong. Turns out that that gage also depends on the material.
Turns out that 14ga alumium is thinner than 14ga steel, and there are differences between thicknesses of 12ga steel and 12ga stainless.
Can anyone shed light on this strange measuring system?
Mike, the same question crossed my mind, but I was too lazy to look it up at the time.
Here it is Sheet metal thickness gages are based on a weight of 41.82 pounds per square foot per inch of thickness. This is known as the Manufacturers' Standard Gage for Sheet Steel, and is primarily used for sheet steel. For materials such as Aluminum and Brass the thicknesses will be different. Thus a 10 gage steel sheet which has a thickness of 0.1345 inch will weigh 41.82*0.1345 = 5.625 pounds per square foot.
