Fabricating Simple Structures

These pages deal with the application of oxygen cutting and arc welding to fabrication and therefore assumes a knowledge of those two processes; the sources of this knowledge are only briefly mentioned.

Fabrication today is blood brother to invention; both have the same mother, necessity. Mechanised agriculture has brought with it a greater use of fabricated steel, in both tractor and implement, and a reduction of cast parts. The greater use of fabrication has come hand in hand with a greater diversity of machines than ever before.

The muitipiication of machines incorporating fabrications has increased both the difficulty and the finance of adequate stocks of spares.

Here fabrication comes into its own. A cast part must be weldable or replaced by a cast part, but a fabrication can be repaired, modified, strengthened, entirely replaced with cutter and arc welder alone; the resources of the foundry are not needed.

Often such fabrication is more expensive than the new proprietary part, but the cost of the part is rarely the main consideration. Time is precious, harvest weather will not wait for spares to arrive. A £1,000 machine cannot economically lie idle for the sake of saving £1.

Often a fabrication can, with advantage, replace a broken casting. Strength will be increased three times on the average, reinforcement can be incorporated where experience dictates, alternatively weight can be saved. A casting must have flowing lines to allow the molten cast iron. to completely fill every part of the mould. Fabrication, on the other hand, can be made the precise shape required in the finished part; no concessions are needed to the manufacturing process.

The fabricated parts used for illustration are intended to teach principles; they are not primarily intended to represent actual parts of machines. For this reason one illustration includes four similar joints, each produced by a different method of welding and each having advantages in a given situation. In actual practice one method would probably be used throughout

The fabrication, but :n this book four different methods are shown to make the most off the illustrations.

The object of this these pages is not to show the precise way in which an exact, number of fabrications can best be made, but rather to help the reader to become'fabrication minded'.

It is not so important to be able actually to make a fabrication as to acquire the menial ability to see in the mind's eye a complicated casting reduced to an assembly of a few simple steel shapes which can then be joined together by arc welding. This will usually have the attendant advantages of increased strength, reduced weight are improved appearance.

The exploded drawing is a farmiliiar, device to those engaged in engineering of every kind. if these pages in some measure helps it's readers to be able to picture a part they have to reproduce in this exploded form, and from that picture to produce the part required, cleanly and simply designed, it will have achieved its aim.