Before the modern era

Originally, millwrights were specialized carpenters who completely designed and constructed mills. Having a working knowledge of driveshafts, bearings, gearing and mechanical belts, they executed every type of engineering operation in the construction of these mills. They designed the patterns of the water wheel systems, carved their gear mechanisms, and finally erected the mill machines.^[5]

In the Hellenistic period, Greek millwrights invented the two main components of watermills, the waterwheel and toothed gearing. Greeks, along with the Romans, were the first to operate undershot, overshot and breastshot waterwheel mills.^[6]

Muslim millwrights adopted the Greek watermill technology from the Byzantine Empire, where it had been applied for centuries in those provinces conquered by the Muslims. They used several solutions to achieve the maximum output from watermills, by either mounting them to piers of bridges to take advantage of the increased flow or by using a shipmill, a type of watermill powered by water wheels mounted on the sides of ships moored in midstream.^[7]

In Medieval Europe, millwrights built the first industrial mills which introduced new innovative uses of waterpower. A survey of the types introduced in Western Europe was conducted by Adam Robert Lucas.^[8]

In China, in the late 14th century, the millwrights were known as jiang and kong (a special term for artisan-engineers) and existed at an early age. They learned their craft on the shop floor, in a kind of apprenticeship scheme.^[9]

Sir William Fairbairn, a millwright of the late 19th century, wrote in his "Treatise on Mills and Millwork", "...the millwright of the late centuries was an itinerant engineer and mechanic of high reputation. He could handle the axe, the hammer, and the plane with equal skill and precision...he could set out and cut in the furrows of a millstone with an accuracy equal or superior to that of the miller himself."^[10]

Modern era

The introduction of the steam engine and the increasing importance of iron and steel changed the global industrial landscape. It created specialisation and the birth of new trades (turners, fitters, machine makers, and mechanical engineers). It also changed the traditional job of the millwright.

As James F. Hobart wrote in his book Millwrighting, "The ancient type of millwright has passed away. He has gone with the old time carpenter and obsolete shoemaker - the former with 500 pounds of molding planes and woodworking tools, the latter with nothing but pegging and sewing awls, hammer, and knife..."^[11]

Through the 20th century, the trade adapted to the change. Modern millwrights work with steel and other materials and must often combine the skills of other mechanical trades in order to successfully install industrial machinery or to assemble machines from pre-fabricated parts. Modern millwrights must also be able to read blueprints and other schematics to aid them in the construction of complex systems. Millwrights are frequently unionized, with estimated numbers of around 45% in the US.^[12]

General characteristics

Millwrights install, maintain, repair and troubleshoot stationary industrial machinery and mechanical equipment in sites such as factories, production plants and recreational facilities. However, the exact duties of a millwright vary depending on whether they are unionized or not, with union rules typically being more restrictive than non-union situations, which may have their own job description.

On a typical job millwrights:^[13]

• read diagrams and schematic drawings and service manuals to determine work procedures
• operate rigging equipment and dollies to place heavy machinery and parts
• fit bearings, align gears and shafts, attach motors, and connect couplings and belts to precise tolerances
• align and test equipment, and make any necessary adjustments
• perform predictive and operational procedures
• repair or replace defective parts
• service and repair hydraulic and pneumatic systems
• may do some welding (when not structural) and tack welding (a weld that is adequate in size to temporarily hold components in place until it can be completely welded by a registered apprentice welder or a journeyman welder when it is structural) and fabrication as well as maintain an inventory of replacement parts.
• may install concrete for supports or flooring as needed.

Modern standards of practice for millwrights also require working:

• within precise limits or standards of accuracy
• at heights without fear
• using of logical step-by-step procedures in work
• planning, solving problems and decision-making based on quantifiable information.

Areas of specialty

Millwrights by nature of their profession have to be extremely well versed in many aspects of construction/demobilization. They may install a conveyor system at an airport one week and the following week work at an industrial wastewater treatment plant.

Training

Millwrights must have a good understanding of fluid mechanics (hydraulics and pneumatics), and all of the components involved in these processes, such as valves, cylinders, pumps and compressors.

They are also trained to work with a wide array of precision tools, such as calipers, micrometers, dial indicators, levels, gauge blocks, and optical and laser alignment tooling.

Most millwrights are educated through apprenticeship programs where they receive a combination of classroom education along with a good deal of on-the-job training. For example, in Alberta, the term of apprenticeship for a millwright is four years (four 12-month periods) including a minimum of 1560 hours of on-the-job training and eight weeks of technical training each year.^[13]

Within the Steelworkers Union, known as the United Steelworkers or USW, the largest Industrial Union in North America, there is also a mix of both classroom and on-the-job training. Upon successful completion of required testing in blueprints, hydraulics, pneumatics, rigging, pipefitting, welding, burning, gears, couplings, and other various types of mechanical fasteners and machinery, as well as mobile equipment and other heavy machinery. A typical millwright serves a 4- year apprenticeship before becoming a journeyman.

Apprentices are usually paid a percentage of the average millwright's wage, and this percentage increases with experience.

A typical training course, to qualify as a millwright, may include, among others, the following:^[15]

• Shaft alignment
• Rigging
• Welding
• Machining
• Electrical wiring
• Steel fabrication
• Conveyor systems
• Steam turbine installation
• Gas turbine installation
• Blueprint basic, intermediate and advanced
• Safety basic, intermediate and advanced
• Labor history
• Associates degree classes