The Astbury Site - Model Steam Terms

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The Astbury A to Z of Model Steam Terms

A

ABS: ABS stands for Acrylonitrile Butadiene Styrene, a type of plastic often used for hulls.
ACS Engineering: This small company is run by long time modeller and steam enthusiast Sandy Campbell. The range includes complete steam plants, boilers, oscillating engines, condenser/oil traps, refillable gas tanks, lubricators and a complete range of steam fittings, many of which are usable as replacements for Cheddar items.
The Taipan (11mm bore), and the new Asp (8mm bore) twin cylinder oscillating engines are direct equivalents in most respects of the well known but no longer made Cheddar Puffin & Pintail/Plover engines.
Aliphatic glue: A type of PVA which is yellow rather than white. It is better for sanded finishes and can be stained.

B

BDC: Bottom Dead Centre.
Bowman: Makers of models and toys. Established by Geoffrey Bowman Jenkins.

C

CA glue: Cyanoacrylates are often known as super glues. These can be used for a variety of materials including wood, metal and plastics.
They cure very quickly to make strong bonds so great care must be exercised. Consider wearing safety glasses and having some debonder (acetone) at hand.
Cheddar: Were makers of model steam engines and boilers for both marine applications and trains. Having called in the receivers Cheddar ceased trading in June 2005. John Woodroofe, who ran Cheddar Models for many years, died in September 2005. Stuart had taken over the designs but currently there is no sign of them offering any of the old Cheddar products.
Compound: Exhaust from one cyclinder used as input to next.

D

Displacement Lubricator: Mixes small amounts of the oil in with the steam as it goes into the engine to provide lubrication to the cylinders, pistons etc.
Double Acting: Steam pushes the piston from both directions alternately.

E

Epoxy glue: Normally mixed from two parts, once set it is very strong.

F

Filler Funnel: A funnel can be very useful for filling boliers and water tanks. There are purpose made Wilesco and Mamod funnels which should be generally suitable or another option is to try and find a funnel for filling perfume bottles.

G

Gas: You need to ensure you run the correct mix for your burner and boiler. A common combination is to have 30% / 70% propane / butane mix gas. Typical brands are Coleman or Taymar and it may be found as plumbing or camping supplies.

M

Mamod: Makers of toy steam engines and boilers. Name is from Geoffrey Malins and MAlins MODels.
Minivap: Class of boat, originating in France, sometimes referred to by the alternative name of Ministeam. Boats are up to 50cm in length.

O

Oil: Use the right type for the right purpose. See Steam Oil.
Oscillating: The cylinders pivot (on something called a trunion) to control the inlet and outlet of steam, instead of the more usual valve gear driven by the crank. This gives a simpler build with less parts and should prove reliable.

P

Pipe Bending Springs: For standard plumbing these are metal spring coils which go inside the pipe to support it during bending and help avoid kinks. For the narrow gauges of piping typically used for steam models much smaller springs are required and so these are then used outside the pipe. The only supplier I know of is K&S Engineering, who supplytubing bender stock No. KS321 for brass, copper and aluminium tubing of 1/16 to 3/16 outside diameter.
PTFE: Polytetrafluoroethylene based tape is used for sealing joints.
PVA: Abbreviation comes from Polyvinyl acetate. Type of glue used for wood. Standard PVA is white, it is readily available, easy to apply and safe to use. Any excess can easily be cleaned using a damp cloth before the adhesive dries.

R

RTR: Ready To Run. A term used to describe model boats that when purchased need a very minimal amount of work in order to be ready to sail.

S

Sanding Sealer: Sealer that fills in pores and hardens the surface wood fibers so that a smooth surface is obtained when sanded.
SEL: Signalling Equipment Limited, makers of toys including steam engines, 1946 to 1965.
Self Starting: For remote control steam boats you will typically need the engine to be self starting, that is to say it should be able to be stopped and started consistently without manual intervention. Single cylinder engines are not considered self starting as the cyclinder may stop in either the top or bottom dead centre (TDC / BDC) positions and would need the flywheel to be rotated to start them again. For a 'self starting' engine go for two cyclinders (or three), with these engines if one cyclinder is at TDC or BDC then the other will be slightly out of phase and so one of the cyclinders should always be able to start moving again.
A word of caution, if your engine is compounded then the self starting properties are those of a single cylinder. This is because subsequent cylinders use the exhaust steam from previous cyclinders so it all comes back to the ability to get the first cylinder moving. On real compound engines this is normally addressed by operating a simpling lever.
Square Engine: A term sometimes used when the cylinder bore and stroke have equal measurements.
Steam Oil: Sometimes also known as Cylinder Oil. A high viscosity oil used to mix with steam to lubricate the cylinders.
Stuart: Makers of model steam engines and boilers.

T

TDC: Top Dead Centre.
Trunion: A pivot, typically used with oscillating cylinders.

Stands for Unit Steam Engine. They are simple oscillating engines which can be constructed in multiples so you could have a pair of them or go for big configurations such as V6 and V8. As standard they have a bore of 8mm and stroke of 19mm. These are low cost engines which typically require some machining and assembly.
The Use kits come in three types:

All the parts to assemble one engine; it is fully machined and ready to assemble.
Parts need machining and a lathe is needed.
As per Unit Engine Kit No 2, but with the brass block drilled out ready for the piston.

V

Valve: Engines use valves to control inlet and exhaust from a cylinder. Many steam engines are slide valve, that is to say that the valve slides open and closed, driven from an eccentric on the crank.