minting coins at the u.s. mints

Here is a short video showing briefly the upsetting of the rims of a blank, and so turning it into a planchet. Also, there are images of the riddler, which shows up at the point in the video where there are a bunch of coins poured into a trough, and a buzzing noise can be heard (which is the vibration of the coins over the riddler.) Mint errors are (supposed) to be removed by this riddler.