You guy's caught the difference between the way original gage measurements were derived, from wire gage thickness, and modern measurements.
Good Call
(come on, even with the accurate history, for modern use the rule of thumb is SPOBI!
)
Gage measurements were originally for plate iron and steel, with the reference to one inch thick metal, and they were later refined to the current thickness tables as milling accuracy and metal quality improved. Stacking the steel will get you into the ballpark, but more because the galvanized coating add thickness rather than raw steel thickness.
The Engineering Fundamentals link is a great resource.
Sheet stock gage accuracy is fairly good with USA and European steel, and less accurate with the current value leader Korean and Chinese steel. The result has demanded oversight groups (SMACNA, UMC, ASHRAE) to revise and increase the reinforcement and gage thickness for different size duct (the most common use for sheet steel). The most recent adopted revisions are 1995 code and guidelines.
On the question if a 22 gage brake is worthwhile? Most automotive body panel steel is 28 to 24 gage, with some thicker sheet in unit-frame assemblies and reinforcements to the unit-body. The brake is more than adequate to bend wheelwell tubs and other non structural parts. If you get the brake, you will find many things that it can do with lightweight sheet and you will question how you worked without it.
The brake limitations are the metal thickness and the width of stock it can work. You will be wishing you had a 6" brake (to form rocker panel supports and large pieces), and then there are the times only a 10" press brake will do the job.
