Metals in Scenery Construction

    Advantages:
    · Stronger and smaller per unit size
    · Allows construction of shapes impossible w/ wood
    · Far more predictable than wood
    Disadvantages
    · Requires specialized tools, skills
    · More difficult to assemble and disassemble

Scenic metals
    · Mild steel
    · Iron w/ low carbon content
    · Weldable, workable
    · Malleable (bends before breaking)
    · Readily available at local suppliers in variety of shapes.
    · Relatively easy to work

Steels not normally used:
    · Carbon Steel: basic form of steel, iron with small amount of carbon added.
        + Hard and brittle
    · Tool Steel: alloy of iron with vanadium or molybdenum added
        + tougher, harder to work
    · Stainless Steel: iron with chromium added
        + Stain resistant but hard and hard to work

Scenic Metals
    · Aluminum
        + Widely used as lighting trussing
        + Lighter per unit strength
        + More expensive
        + More difficult to work, esp. to weld
        + Requires oxygen-free atmosphere to weld
        + Only weld with Heliarc or MIG welders
        + Softer than steel, burns at lower temp.

Metal shapes
    · Tubing, round, rectanguar, square
    · Solid rods
    · Structural shapes, Channel iron, I-beams, angle irons
      t-bar, flat strap  

Cutting metals: manual methods
    · Cold chisel and hammer
    · Machinist’s vice and chisel as shear
    · Hack saw
        + Sized by teeth to the inch
        + 3 teeth on material being cut

Cutting Metals: power methods
    · Power hacksaw
        + Reciprocating saw w/ metal blade
    · Metal cutting band-saw
        + Portaband
    · Abrasive saw “chop saw”
        + Abrasive blade in skil saw
    · Cold saw
        + Very clean cuts, but expensive blades

Welders
    · Oxy-acetylene: Oxygen/Acetylene flame
        + Slow but easier to learn
    · Good for thin stock
        + Arc Welders
    · Stick Welders: AC or DC
    · Wire Feed Welders
        + Flux core wire
        + MIG Welders

    · Filler metals must match base metal.

Soldering and Brazing
    · Joining metals with dissimilar metals. 
      The higher then tempurature, the stronger the joint.
    · Require Flux to keep Oxygen out of joint
        + Acid flux: everything but electrical
        + Rosin flux: for electrical work

Solder: originally an alloy of Tin and Lead.
    · Lead now often replaced with antimony or bismuth
    · Silver solder, uses silver rather than lead 
      stronger than lead solder.

Brazing: soldering with Bronze high temp, but less than welding.
    · Uses Borax based flux
    · Works on cast iron

Mechanical Fasteners
    Bolts
    · Available in various grades
    · Grade 1 to Grade 8
    · Sized by number and diameter
    · Threads: NC and NF

Mechanical Fasteners
    Sheet metal screws
    · Harder than wood screws, sharper points and threads
    · Available in variety of head types
    · Pan head and flat head most common
    Tek screws (drill point screws)
    · Variety of sheet metal screw with attached drill point

Mechanical Fasteners
    Rivets: strong and permanent, but difficult to remove.
    · Blind rivets (pop rivets)
    · Not so strong, but easy to use
    · fastened from one side

Pipe and Tubing
    PIPE:
    · Primary use NOT structural, shape not the most efficient 
      but is readily available and can be used with care.
    Types:
    · Black iron or Gas pipe
        + Cheaper, less slick, rusts
    · Galvanized water pipe
        + Same pipe with zinc coating slicker but won’t rust.

Sizing Pipe
    · Available from 1/8” I.D. on up.
    · Stage use: usually between 1/2” to 2” typical Schedule 40 Standard most common.
    · Specified by Inside Diameter (I.D.)
        + 1/2”= 0.62” ID x 0.84 OD
        + 1 1/4”= 1.38” ID x 1.66” OD
        + 1 1/2”=1.61” ID x 1.9” OD
        + 1 1/2” most common for structure.

Pipe as a Beam
    · Example: Rigging batten
    · Circle cross-section subject to collapse from point loads.
    · Best if max. span between supports kept to 10 ft. 
      Longer spans should have added support.

Pipe as a Column
    · Tall, thin columns subject to buckling sideways.
    · Require bracing if column height is excessive, 
      about 10 ft for 1 1/2” pipe.

Joining Pipe: Threading
    · Designed to hold gas or fluid, 
      but threading pipe reduces wall thickness.
    · Pipe will always be MUCH weaker at joint.
    · Gives easy, trim, neat connection, but prone to break under stress.

Sleaving
    · Slide a smaller pipe inside larger at joint and bolting through.
    · Strong as the smaller pipe stronger than threading.
    · Best method of joining batten pipe.

Assembling pipe structures
    Threaded plumbing fittings:
    · Available as straight, T’s, L’s, etc.
    · Neat and trim, BUT threading weakens joints.
    · Requires accurate cutting and threading.
    · Pipe joints are cast iron inherently weaker, less trustworthy. 
      More brittle and less predictable.


    Kee Clamps: cast fittings assembled with set screws.
    · Quick to assemble and strong.
    · Requires accurate cutting of pipe.

Pipe clamps
    Cheeseburoughs:
    · Quick and easy to apply.
    · Not rated as a load bearing clamps.
    · Makes a large profile joint.

Rotalocks
    · Creates a load-bearing joint.
    · Somewhat awkward to assemble pipe slid on from end, then locked with rotating cam.
    · Easy to tighten, but expensive ($40).
    · Makes a low-profile joint.

“Pipe clamps”
    · Creates a load-bearing joint.
    · Similar to rotalocks, but locked with wedges rather than cam.
    · More difficult to assemble and tighten, but much cheaper ($6)
    · Makes a low profile joint.

Specialty shapes
    · Slotted angle “Dexion”
    · Pierced tubing “Telspar”