Above: quick-change tooling system for the Bridgeport R8 spindle fitting. The hardened and ground, alloy-steel "Master Adaptor" - with a key-driven retaining ring - was able to hold a variety of adaptors (shown below) designed to connect with straight and taper shank drills, boring heads, boring tools, reamers, end mills, fly cutters, chucks and a variety of other tooling. Unlike most other tooling, the Bridgeport set did not require the spindle to be locked when a change was made.

Fly-cutter Adaptor to accept both #3 and #4 Bridgeport-branded fly cutters.

Shell-mill Adaptor to accept 0.75-inch and 0.5-inch arbors.

Taper-shank Adaptors - able to hold No. 1 and No. 2 Morse, and No. 5 and No. 7
B & S.

Jacobs-chuck Adaptor - made in a variety of sizes to accept the standard tapers found in the back of Jacobs drill chucks.

Boring-head Adaptor - made to accept the No. 1 and No. 2 Bridgeport boring heads.

Straight-shank Adaptor - made to accept 1/8", 3/16", 1/4", 3/8", 1/2", 5/8", 11/16", 3/4" 13/16" and 7/8" - and doubtless metric sizes as well.