Specializing in Geometric Abstract Sculpture

Fabricating a Steel Sculpture

 

     Steel sculpture fabrication is the method of building steel sculpture by cutting, bending, assembling (welding), and finishing processes.  Each technique and its related processes require a certain degree of mastery that most people only achieve after years of practice involving trial and error. 

 

Cutting

 

     Most of my metal pieces are cut to a 1/16 to 1/8 inch oversize by a hand or hydraulic metal shear machine, a saw, a grinder, or even a rotary tool with cutting-tip accessories.   After the cut, I have the piece machined to precise specification with a milling machine.  However, stainless steel plates that are ¼ inch to 1¼ inch thick are best cut by a more robust cutting machine such as a plasma, laser, or water jet cutter.  Plasma cutters have an extremely hot tip, which allows me to make more abstract cuts than are possible with shears or most other cutting tools.

 

     For cutting inlaid circles or semi-circles, I often rough-cut a rectangular or triangular work piece with an plasma cutting torch. I then have each piece bored or milled to precise specification with a milling machine or lathe.

 

    Quite frequently, I use a die or angle grinder to grind down various surfaces or to add surface textures to the finished steel sculpture.  A die grinder is much lighter and easier to handle than an angle grinder, and allows for greater control over the tool or tip.  However, regardless of the type of grinder used, I typically do grinding and surface texture operations gently and in small increments to prevent overcutting and destroying the work piece.

 

Bending

 

     When I fabricate a piece of metal to be used for an abstract geometric sculpture it is often necessary to perform curving and intricate bending operations.  Either of these operations can easily be achieved by hand leverage, a hammer, or a home made tool if the metal work piece is small enough to handle and maneuver.  On larger and thicker pieces of metal – particularly stainless steel sheets, plates, and bars – I prefer bending with a robust bending machine or press brake and using the appropriate methods and processes.  Bending with this equipment requires that it be done as fast as possible due to the work hardening characteristics of stainless steel.  As well, it is important to achieve a certain degree of overbend to compensate for springback from the bend.

 

     Another method I use to bend stainless steel and other metals is heating.  The specific heat bending method I use involves two main steps:

• After clamping the metal work piece into a vice, I use an oxy-ace torch to heat the area of the metal I need bent until it emits an even orange glow. 

• I then turn off the torch and while the metal still has an orange glow, I hit it with a hammer until the desired bend is achieved.   

     

     A general rule of any heat bending method is the larger and thicker the size of the work piece, the less chance the bending operation will result in the exact desired bend.  This is because heat bending is an art more than an exact science.

 

     Two final points: The metal’s composition, shape, thickness, and overall size are important factors to consider when selecting a specific metal bending method, process, or equipment.  Also important is the bend angle, bend radius, bend size, curvature of the bend, and location of the bend on the metal work piece.

 

Welding

 

     I use three different welding techniques which vary depending on the piece and stage of fabrication.  The technique I prefer and most often employ is TIG welding because of its ability to achieve precise, intricate welds, clean joints, and smooth surface finishes, and its tendency to generate less splatter and therefore less clean-up.  Prior to any welding it is important to properly clean and prepare the area to be welded.  Cleaning often involves wire brushes or wire wheels and the use of a pre-weld acid to remove any impurities that might contaminate or compromise the weld.

 

     “Stick” welding or Shielded Metal Arc Welding, the simplest of the three processes, creates an arc by passing high electric current through a coated metal rod to the grounded pieces to be joined.  The heat generated vaporizes the rod coating, shielding the pieces being melted together.  Overfill, splatter, and “slag” – a residual I manually remove with a hammer and wire brush – are side effects of stick welding.  I find stick welding most appropriate for less intricate work, larger pieces, and areas that require strong welds but do not necessarily require a precision finish.

 

     “MIG” welding or Gas Metal Arc Welding (GMAW), also an electric arc process, feeds a thin metal rod/wire and an inert shielding gas mix (argon/helium) through a welding gun to create an arc. The process creates raised, smoother, cleaner welds with no residual “slag.”  MIG welding, while cleaner and more precise than stick, requires a “calm” atmosphere free of wind and excess moisture, which cause imperfections in the weld.  Surrounding exposed parts are masked to prevent splatter and unnecessary cleaning.

 

     “TIG” welding or Gas Tungsten Arc Welding (GTAW), like MIG welding, is an electric arc and gas shielding processes. However, TIG welding does not require the consumption of any additional metal (i.e., no additional stick/rod/wire is needed but may be added if necessary).  The process uses an inert gas to create a shield around a tungsten electrode which creates or receives an arc to melt and combine the base metal pieces together, forming a strong bond.  When no additional metal is added in the process, the resulting weld is a flat, smooth weld with no splatter or slag, making TIG welding the most appropriate weld for smaller, more intricate, and highly visible joints. 

 

     After welding is complete, I clean and inspect each weld for porosity, cracks or other imperfections.  Imperfections are cleaned, ground-down, and re-welded until the desired weld is achieved. Some of the welded pieces require a second grinding and sanding operation to smooth welds to a precise surface before moving on to the finishing process below.  After the finishing process is completed, the weld joint will be nearly invisible and impossible to spot with the naked eye.

 

Finishing

 

     The finishing process involves two phases: sanding and buffing.  The first phase, sanding, starts with a rough abrasive (60 or 80 grit) and eventually uses a fine abrasive, such as 120, 220, 320, 400, and higher grit abrasives, until the desired finish is achieved.  The rough grit is designed to remove imperfections on the metal surface like pits, nicks, lines, and scratches.  The finer abrasives leave progressively finer lines that are not visible to the naked eye.

Most of my stainless steel sculptures have a #8 (mirror) finish, the achievement of which requires  using buffing compounds, polishing wheels, and high speed polishing machines or other machining tools that can be used for polishing, including an electric drill. 

 

     The buffing steps I use include two types of motion: the cut motion and the color motion.  The cut motion is designed to give a uniform, smooth, semi-bright surface finish.  I am able to achieve this by moving the metal object against the rotation of the buffing wheel, while using medium to hard pressure.  The color motion gives a bright, shiny surface finish.   I am able to achieve this by moving the metal object with the rotation of the buffing wheel, while using medium to light pressure.