Being a junior Dr Johnson is hard work!
Cast Iron. A range of about 30 different high carbon/iron mixes, very fluid when molten and good for casting. Different variants are used to make Brake Blocks, Engine Blocks, Machine Tools, Pipes and Street Furniture etc. Quality ranges from very poor to very high. Easily machined except liable to have a very hard outer skin, very dirty, no cutting fluid needed. Strong in compression, weak in tension.
DTI : Dial Test Indicator. An instrument used to measure small distances (0.01 to 0.005mm). Used to accurately position work and to test the roundness, droop, or deflection of a work piece.
EN1A (aka 230M07). A type of Mild Steel suitable for machining general purpose components to a good finish. Low tensile strength (for a steel). Cannot be heat-treated. May be case hardened.
EN1APb. As EN1A but softer and more easily machined. Must not be welded.
Work Hardening. A phenomenon whereby a material becomes harder and more difficult to machine as it is worked. Some stainless steels can become harder than the tools being used to cut it. The problem is exacerbated by over-gentle cutting or blunt tools.
Lathe. A metal working machine that cuts by rotating the work against a fixed cutting tool.
Mill. A metal working machine that rotates a cutting tool against a fixed work piece.
Reamer. A tool used to finish a drilled hole to an exact size by removing a small amount of metal.
MT2. A specification for a wedge tool holder. A male shank on the tool is tapered to fit into an equivalent female socket, for example a lathe tailstock. The wedge action of the taper stops the tool rotating whilst still allowing it to be pulled out and exchanged.
Plutonium. Silvery-white metal. Radioactive, hot, highly toxic and highly reactive. Critical mass about 10kg (a 100mm diameter sphere) Used in the boiler of an enhanced LBSC 'Tich' being built by Guy Martin for the 2018 IMLEC