Isabella quarter is without distinction". The "American Journal of Numismatics" had other criticisms of the quarter: Minting of what Barber dubbed "showy quarters" began at the Philadelphia Mint on June 13, 1893, six weeks after the exposition opened. Leech had planned to strike the pieces using polished blanks, or planchets, and workers at that mint handled the coins carefully; unlike the half dollar, surviving specimens display relatively few contact marks from other coins. The first piece struck, along with numbers 400, 1,492, and 1,892, were struck in proof condition and sent to the Lady Managers along with certificates attesting to their status.
Metal spinning attached. In CNC applications, carbide or tool steel cut-off tools are used. The mandrel does not incur excessive forces, as found in other metalworking processes, so it can be made from wood, plastic, or ice. For hard materials or high volume use, the mandrel is usually made of metal. Several operations can be performed in one set-up. Work pieces may have re-entrant profiles and the profile in relation to the center line virtually unrestricted. Forming parameters and part geometry can be altered quickly, at less cost than other metal forming techniques. Tooling and production costs are also comparatively low. Spin