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Wig-Wag Engine

The Original

Engine Designs by Ade Swash

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The Wig-Wag Concept

The Wig-Wag Engine has been designed to be an easy introduction to model engine making for the beginner, and the vertical wig-wag is the starting model from which the Wig-Wag family is based upon.

Using a simple oscillating cylinder with a 15mm piston bore and a 30mm stroke, the engine runs very well at moderate and slower speeds, on both compressed air and steam, and is a pleasing engine to run and watch.

All the engines from the Wig-Wag family are built from aluminium, brass, steel and phosphor bronze bar stock which is readily available from metal stockists and model engineering suppliers, and does not use specialist castings or difficult to get hold of parts.

The majority of the engine parts are modular in their design, and are common to all the engines in the Wig-Wag family.

Start by building the Original Vertical Wig-Wag, and then choose to build one or more of the family.

Any hobby engineer with a modest workshop will find this an enjoyable build, and the construction covers most of the bases of model engineering such as turning, milling, threading, reaming and boring.


Drawings and Build Notes

Some of the downloadable drawings are complete as a set, others only detail the chassis specifications. There is a common components drawing (Drawing C) which should be used in conjunction with the basic chassis drawing. The generic 'build notes' word doc also accompanies the drawings.

Great News for Imperial Inch modellers!

We have just added a new PDF for our users who prefer to work with inch imperial sizes. This will make your work even more efficient and convenient.


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Currently there is the common components drawing and the chassis dimensions for the original WigWag and the Inverted wigwag. Conversion kindly created by Jon Edwards.

Build Notes



Drawing C

Common Components



The Original Vertical Wig-Wag Engine

This is the first engine that was made for the Wig-Wag family, and is a single cylinder vertical oscillating engine, which is easy to build and a great first engine for anyone wanting to start model engineering.

All the engines from the Wig-Wag family are built from readily available bar stock, and do not use special castings. The majority of the engine components are modular in design, and the dimensions are identical, allowing different designs of engine to be made which all have a common identity.

If you are new to building a Wig-Wag engine, then it is the ideal engine to start with and you can see an 8 part step-by-step video series on how to build this engine by following the youtube link below.

How to build a Wig-Wag Engine - Part 1 of 8



The Original


Original Wig-Wag Drawings & Build Notes

CAD Drawing

by David Gardener

The Horizontal Wig-Wag Engine Mk1 

This engine uses a single cylinder design identical to the original Wig-Wag, but using a horizontal chassis layout. This was the original Mk1 chassis and has been updated to use the standard wigwag engine components detailed on Drawing C


Wig-Wag Horizontal Chassis

The Horizontal Wig-Wag Engine Mk2 

This engine is Mk2 of the horizontal design, which follows a design which is more similar to the original wig-wag chassis. This uses the common components detailed in Drawing C.



Drawing C

Common Components

Wig-Wag Horizontal


The STRETCHED Horizontal Wig-Wag 

This engine design was based on a concept by Chris Shanks.

It follows the format of the Mk1 horizontal Wig-Wag but has had the chassis stretched to create a longer engine. The cylinder has also been stretched to suit the design, and the crank disc increased to create a 42mm stroke length, to give a nice slow running engine.


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Wig-Wag Horizontal



The V-Twin Wig-Wag Engine 

This interesting engine has a two cylinder arrangement set at 90 degrees to each other in a classic V shape, and uses a a pair of split crank connectors to connect to the crank journal, a brass crossover tube connects the two cylinders to distibute the air or steam input, and the engine creates a lovely twin cylinder sound when running. 




Drawings &

Build Notess

The Twin Wig-Wag Engine 

The Twin Wig-Wag engine is simply two vertical WigWags back to back, a slightly wider flywheel is used to 'fill' the extra space between the chassis which is needed to allow access to the spring tensioner. A shorter spring is also used to keep this compact. A straight brass crossover tube is used to connect the single air supply between the engines and the cranks are set at 180 degrees to each other


The Duplex Wig-Wag Engine 

The Duplex Wig-Wag has a single chassis plate but with a cylinder on either side, the axle bridges across a dual crank to a support chassis for the flywheel. A copper tube connects both cylinder input ports and a single supply tube connects these to the air or steam supply.



Wig-Wag Duplex

Drawings &

Build Notes

The Triple Wig-Wag Engine 

This engine is a lot of fun to make and a joy to run, having three in-line cylinders each on a standard vertical chassis, the 3-part axle shaft is interconnected using dual cranks between the individual engines, creating one continuous motion. The cranks are set at 120 degrees apart, allowing the engine to always be self starting.



The Inver-Wag Inverted Wig-Wag

This engine turns the WigWag on it's head, by simply inverting the chassis to place the flywheel at the top. It is a very simple chassis design which is easily made, and creates a lovely inverted WigWag engine



Inverted Wig-Wag




The Micro & Nano Wig-Wag Engines

The scale of the Wig-Wag engines have been reduced to half-size and one-quarter size to make the Micro and the Nano engines, both of which are fully functional and great fun to run. If anyone fancies a real challenge, then it would be great to see a one-eighth scale version one day!



Wig-Wag Micro


Wig-Wag Nano

Wig-Wag Accessories

The Drop Hammer 

The Drop Hammer is the first 'accessory' I have built for the Wig-Wag engine series, and is designed in a similar style and an easy-to-build format. It can be driven by any of the Wig-Wag engines with the use of an 18mm drive pulley added to the Wig-Wag.



Drop Hammer


CAD Drawing

by David Gardener


The Wig-Wag Lathe

This miniature lathe is built in proportion to be driven by the original vertical Wig-Wag engine.


There are no drawings available as this was scratch built 'on the fly' from materials I had in my scrap box, but is a beautiful accompaniment to the wigwag series.

Click below to watch the video



More accessories will be added as they are built

These are concept sketches of Wig-Wag designs which have been created by David Gardener.

The beauty of the modular design of the Wig-Wag series is that any of the single engines can be duplicated to make a series, such as the 3,4,6,8 cylinder and so on


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Horizontal Opposed

2 and 6 Cylinder

Concept Designs


Wig-Wag V4 and V8

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Wig-Wag Radial Engines

3 and 5 Cylinder


Double Duplex


Ade Swash – 2021   Contact me at

Many Thanks to David Gardener for the CAD drawings

Last updated 08/06/23 


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