Design and Manufacturing

The Making of... - The Slicing of ...


The Making of ...

... a typical COX cylinder

  • start with a plain bar stock material of leaded steel,
  • drill step bore for piston and glow head,
  • shape fins and foot using special tooling,
  • add the threads for glow head and crankcase.

These operations were performed using an automatic screw machine, typically producing 300 raw cylinders per hour.

  • machine two flats at top fin (not all models),
  • cut the exhaust slots.
  • machine transfer passages,
  • apply black oxide,
  • hone cylinder bore.

Above the exhaust ports, the honing produced a slightly tapered bore with a prescribed accuracy of better than 2/10000 of an inch. Below the exhaust ports, the taper was increased to reduce friction.

Cylinders were produced with one and two bypass channels.

Tee Dee engines used wider bypass channels, which were enlarged by milling along the vertical edges of the standard bypass channels. All engines, except for the .15 Mk. II have two exhaust ports.

Many more details as well as an explanation of the basic numbering system, can be found in the articles by Dan Sitter, published in the Engine Collectors Journal (ECJ).


The Slicing of ...

click to enlarge (20 kB)

... a Cox Tee Dee .051

If you take your secret X-ray glasses, you can look  into your Cox engine. You will notice many details of its clever design, for example

  • the lightweight hollow spinner,
  • the thrust washer behind propeller drive washer for electric starters,
  • front crankshaft relief acts as oil reservoir for lubrication and reduces friction,
  • tight fit of plastic carburetor housing,
  • smooth venturi with circumferential grove and spray holes,
  • very large rectangular crankshaft port,
  • twin transfer channels, enlarged along their vertical edges,
  • the conrod with its upper end ball socket,
  • glow head with insulated center pin,
  • a crankcase cover, which is maybe too thick .