If metal is shrunk in a collision or in fabrication by being deformed while it is under compression then upsetting occurs.
How thick sheet metal for automotive.
Brianstick with all due respect i find it hard to believe that sheet metal from a 1974 american made automobile has 18 ga.
Automotive sheet metal once ran in the range of 18 gauge which was 48 thousandths of an inch thick actually 0 0478 inch.
You can get pop rivets down to 1 16 inch shaft size up to 3 16 inch at your local hardware store.
Sheet metal gauge size chart gauge or gage sizes are numbers that indicate the thickness of a piece of sheet metal with a higher number referring to a thinner sheet.
0299 and 24 ga.
Gauge to thickness chart gauge stainless galvanized sheet steel aluminum fraction inches mm inches mm inches mm inches mm 30 0 0125 0 33 0 0157 0 40 0 0120 0 30 0 0100 0 25 29 0 0141 0 36 0 0172 0 44 0 0135 0 34 0 0113 0 29 28 1 64 0 0156 0 41 0 0187 0 47 0 0149 0 38 0 0126 0 32.
Sheet metal used on the auto body of new vehicles and when aftermarket body work is performed tends to be between 20.
0239 range depending on the panel.
This is done by upsetting it literally compacting it into itself so that some of its lateral dimension can be exchanged for increased thickness.
History of the gauge system.
The opposite is also true.
20 gauge became common in more recent times and this meant 0 0359 inch thick metal still a lot to work with in bumping and metal finishing.
Rivets come in a variety of head and shaft sizes.
You can also choose a depth for the rivet if you re just joining two sheets of metal a shallow depth works best.
For example in one gauge system 18 gauge steel measures 0 0478 inches thick but 18 gauge aluminum is 0 0403 inches thick.
The equivalent thicknesses differ for each gauge size standard which were developed based on the weight of the sheet for a given material.
If you re riveting a thick sheet to a piece of angle iron you need a deeper rivet.
That is the metal must be shrunk.
There are several different gauge systems used today with specific gauge designations used for specific metal types.
The reason i say this is that i have rebuilt two older vehicles a 55 chevy and a 67 el camino and have found the sheet metal to be in the 22 ga.