Editing IBM Model F (section)

==Common design features==
Model F keyboards were the first to use IBM's buckling spring key mechanism, designed to replace IBM's costlier and more complex [[beam spring]] keyboards. They were lighter and more compact, to the extent that IBM's sales literature described them as "low profile" and "ergonomic". The Model F utilized the same capacitive sensing technology as the beam spring keyboards with very similar electronics and PCBs.<ref name="xwhatsit" />

The Model F's internal assembly consists of a curved steel back plate and a curved steel top plate with the switches and PCB sandwiched in between. The flexible [[printed circuit board|PCB]] has slots in it that slide onto pegs on the back plate, and it conforms to the curve of the bottom plate when attached. There may be a thin plastic sheet between the PCB and the back plate, presumably to help electrically insulate them from each other. The springs with their attached hammers (the 'Pivot Plate Assemblies' in IBM terminology) are housed in removable barrel modules that slide into holes on the upper plate, with an additional notch or peg to maintain the alignment. The barrels with pegs are commonly referred to as "XT" barrels, and are found on XT-layout Model Fs, and the 3178 Model F and its relatives. The barrels with notches are commonly referred to as "AT" barrels, and are found on the Model F AT and nearly every other type of Model F. The pegs on "XT" barrels would interfere with the stabilizer wires found on AT, 4704, and 122-key Model Fs, which may have been the reason IBM changed the design. All model F keys that are unstepped and wide enough to require stabilization use wire stabilizers. The Model F AT's enter key uses a combination of a horizontal wire stabilizer and a rectangular stabilizer insert in the barrel that the \| key normally occupies. The "rod" stabilizers found in most Model Ms beginning in 1985 do not appear in Model Fs.

There is a sheet of foam with holes in it that goes in between the switches and the top plate which maintains constant pressure between the top and back plates. This foam is prone to degradation. The top and back plates are held together with a series of interlocking tabs, with one longer tab from the top plate folded over the bottom plate to keep them from moving relative to each other.

Model F keycaps are the same dye-sublimated PBT as those used in the later Model M, although over time there were changes to the dyesub characteristics and slight changes in the design of the slider. The first Model Fs launched with one-piece keycaps, but the later 122-key PC 3270 and 3179 terminal keyboards started using two-piece keycaps. IBM sold some sets of the top part of the two-piece keycaps for users to change the layout of their keyboard themselves.

All the keycaps on the Model F are the same profile and can be used on any row. The curve of the assembly simulates a curved keycap profile, in contrast to IBM's Beam Spring keyboards and Cherry's G80 keyboards which have a unique keycap profile for each row to achieve a curve relative to the flat switch plate.