Presentation on theme: "STEEL Steel is a combination of iron and carbon. There are different formulations of steel for various uses. There is stainless steel used for forks and."— Presentation transcript:
STEEL Steel is a combination of iron and carbon. There are different formulations of steel for various uses. There is stainless steel used for forks and spoons, and tool steel used for scissors and screwdrivers. Steel formulations are made to different strengths and rigidity. Steel that is made very rigid (like tool steel), will break before it bends. The steel we usually build with is soft steel called A36. Very much like play dough this steel can be formed into any shape depending on the mold you push it through. Because all the shapes are the same formula of steel we can weld them together.
Steel is a material that is harder than wood to work with but it has its uses. When we need to have a lot of structural strength in a small space we use steel. The same strength in wood would take up much more space. Another use is something that is going to be used for a long time, such as on a tour, and needs to take a lot of abuse. Steel has that durability but it also has weight.
Shapes The more common shapes of steel building material are I T L C box tube, bar, rod/ dowel and pipe The shapes are sized depending on the actual size of the steel. A rectangular bar has two sizes- the width and thickness. An angle (L) will have three- width of one leg, width of the other leg, and thickness. Box tube, I, T, C will also have three measurements.
Pipe Pipe is usually purchased from plumbing companies and has different descriptions. Pipe is specified by its interior diameter (plumbers care about how much water can go through), and the thickness of the walls called schedule. The pipe we usually use in theatre (all the flying pipes) is 1 ½ Schedule 40 pipe. Pipe often has threads cut into the ends so you can screw the pipes together with various connectors. This allows anyone with money but no shop facilities to build things with steel.
Steel can also be used in sheets. Unlike wood these sheets come in a variety of sizes. They also come in various coatings. Basic plain steel is called cold rolled. Steel that has been given a zinc coating to prevent rust is called galvanized. Sheets come in various thicknesses called gauge. A sheet that is 8 gauge is very thick, aluminum foil is about 64 gauge.
Wire and wire mesh Wire is also described in gauge. In theatre we often use 16 gauge black wire (basic A36 steel wire) to secure props and for an unlimited number of special circumstances. Wire is also made into wire mesh for various uses. The kinds that we tend to use in theater are- There are other metals that are commonly available in wire form. These are also sized by gauge and are used for prop and decorative uses on stage.
Wire Mesh Hardware cloth -sometimes called rabbit wire, square holes, ½ and ¼ are the usual sizes. Chicken wire- used for poultry, hexagonal holes, great for forming irregular shapes
Expanded steel mesh- this is heavy duty material, diamond shaped holes, used for platforms and surfaces that have to support weight but allow light through. Welded wire- this is inexpensive fencing with rectangular holes.
Aluminum Steel has one major flaw- it rusts. Steel that is galvanized to prevent rust is difficult to weld and paint. We have another option for metal construction in the entertainment industry- Aluminum. Aluminum doesnt rust, its lighter, and the material comes in the same sizes and shapes as steel.
Aluminum for Touring When building things for tours weight is a serious consideration. The cost of transporting steel truss is more than the added cost of building with aluminum in the first place. This is why most all touring trusses and structure is aluminum.
Steel construction Here are some ways that steel is used in building (theatre and otherwise). Steel rebar and wire mesh are used to create the structure for natural shapes made out of concrete.
Steel channel is used extensively to replace 2x4 studs in construction. This is cost effective and fire proof. This method of building is becoming more common in the entertainment industry.
There are other metals we can use in theatre. We can use almost anything (if the budget allows) should the show require it. If the material is too expensive we can always fake it. Copper wire and tubing, and various brass parts are commonly available.
Welding and Metal Cutting
In order to make steel structures we need to cut the steel to length and attach the pieces of steel together to create solid frames.
Metal Chop Saw
The metal chop saw uses an abrasion blade that grinds its way through the steel. The blade gets smaller with every cut and eventually needs to be replaced.
Band Saw The band saw has a continuous blade of small metal cutting teeth that cuts using its own weight to press down.
Oxy Acetylene Welding
This kind of welding uses two gasses (oxygen and acetylene). The acetylene burns easily and the oxygen is added to make the flame burn very hot. This is then used to melt the steel.
When welding in this method you need to set the two gasses to achieve a very hot flame and then use your other hand to add steel into the weld using a separate rod of special metal.
Oxy-acetylene welding rigs can also be used to cut through very thick steel in difficult patterns. This is their usual use in theatrical shops.
Arc welders use electricity to melt steel. They create a high voltage circuit of electricity using the grounding clip attached to some point on the material and an arc welding electrode rod at the other end.
MIG Welding ( Metal Inert Gas)
The MIG welder is also an electric welder that uses an arc of current. The difference is that the mig uses a roll of wire that is fed through the welding gun continuously instead of an electrode rod. It also uses inert gas (carbon dioxide or argon) blown through the welding gun to push the oxygen in the air away from the weld.
This is a MIG unit with the gas canister attached.