Sheet Metal Fabrication Tools

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					Sheet Metal Fabrication Tools
      From the Instructors @
             HRI
       The Hot Rod School
                       Sheet Metal
                     Fabrication Tools
 Larger Sheet metal fabrication tool are
  not a necessity in sheet metal
  fabrication, but it sure speeds up the
  procedure.
 In this session we will explain briefly
  how some of the larger fabrication
  machine works.
                                     Sheet Metal
                                   Fabrication Tools
   Advanced sheet metal shaping:
       There are basically only four things that
        can be done to metal; cut it, weld it,
        stretch it, shrink it. Master these things
        and the only limit you have is your
        imagination!
   Compound curves:
       Compound curves are defined as sheet
        metal that bends or contours in more
        than one direction.
       Compound curves make sheet metal
        shaping difficult, especially for beginners.
                              Sheet Metal
                            Fabrication Tools
   When creating a compound curve, it will
    require both shrinking and stretching.
       Whenever a sheet metal panel is stretched the
        surrounding area will shrink or will need to be shrunk.
        When stretching a shape into a flat panel the outer
        edges must be shrunk or an effect called the “Bottle
        Cap Effect” will occur. The Bottle Cap Effect is when
        metal bunches up or puckers around the edge of a
        panel being stretched or “worked”, resembling the
        wrinkled edges of a bottle cap, these edges must then
        be shrunk down to smooth the panel edges and may
        help raise the area being stretched.
        Sheet Metal Fabrication Tools
   Tools used to create compound curves:
       Many different tools can be used to create compound curves
        whether they are high or low crown, by simply changing dies or
        rollers in many of the powered machines you may form many
        different high and low crown panels with the same machine.
       Below is a list of some of the equipment used to make many
        compound curve shapes.
       Mallet and tree stump
       Mallet and shot bag
       Shrinker/stretcher
       Planishing hammer
       English wheel
       Power hammer
       Hammer forms
       Pullmax machine
       Bead Roller
                                           Sheet Metal
                                         Fabrication Tools
   Mallet and tree stump procedure:
      Make a template or buck to the desired shape, armor makers didn’t have
       the luxury of cardboard templates or wooden bucks, instead the suits of
       armor were fitted to the man, a “human” buck.
      Hollow out the top surface of the tree stump to the general desired shape.
      Choose a mallet with the desired finished shape of the panel.
      Draw the desired outline of the shape on the panel to be shaped.
      Start hammering in the middle of the concave area of the stump working
       towards the outer edges. Do not try to get all the shape all at once, work
       slowly from the center out.
      Notice how the edges of the panel wrinkle (the bottle cap effect) while you
       hammer in the center, the edges are trying to shrink themselves. These
       wrinkles should be shrunk down during the stretching process, do not wait
       until all the stretching has been done. If you wait until finished stretching,
       you may fold the wrinkles over and have more difficulty shrinking the outer
       edges.
      The wrinkled edges can be shrunk with a flat, leather or soft wood mallet
       or a mechanical shrinker can be used. This is called “cold shrinking”.
                            Sheet Metal
                          Fabrication Tools
   Mallet and shot bag procedure:
       The shape of the bubble or blister should be
        drawn on the panel to be shaped. All hammer
        blows should be applied inside this area using
        the mallet.
                            Sheet Metal
                          Fabrication Tools
   The pneumatic planishing hammer:
       Pneumatic planishing hammers became
        available in the very early 1930’s and were
        very popular in body repair shops through the
        late 1950’s. During these years it was more
        economical to use labor for body repair
        instead of replacement panels.
                                Sheet Metal
                              Fabrication Tools
   Shrinker/stretcher:
       Shrinkers and stretchers are just that,
        machines designed to shrink or stretch metal.
       There many different types available, hand
        operated, foot operated, and powered (air or
        electric). The hand operated is the most
        popular because of their low price.
       All dies come in sets; shrinking dies have two
        upper and two lower dies. These dies are
        designed to have sheet metal inserted
        between them. When the lever is depressed,
        the dies come together, grabbing the metal       Kick
        and forcing it together, shrinking it.           Shrinker
                                             Sheet Metal
                                           Fabrication Tools
   English wheel:
      The English Wheel is a very old machine with an uncertain
       beginning. One story is that a jewelrysmith in Europe took the
       idea from a small rolling mill that manufactured wire stock, and
       then made a small frame to hold the two rollers and used it for
       smoothing small sheets of gold for jewelry. The idea caught on
       and spread through Europe, but seemed to be most popular in
       England. This is most likely where the name “English” Wheel
       comes from.
      The English Wheel has been used in many countries over the
       years, but gained widespread use starting in the very early 1900’s
       for shaping automobile and truck bodies and then airplanes.
      Mainly used by coachbuilders, some early automobile dealers and
       body repair shops purchased miniature hand held versions (called
       fender smoothers) of the wheel to run over fenders to smooth the
       less than perfect fenders on new cars.
      The Wheel is best suited to use after a panel has been shaped in
       a shot bag and then the Wheel is used to smooth out the lumps. A
       sheet metal panel can be raised completely by using the Wheel
       but, for a high crown, the fastest method is to use the shot bag
       first.
                         Sheet Metal
                       Fabrication Tools
                              The Upper Wheel:
Use of the English wheel      The large, flat
                              wheel is free to
                              spin but is not
                              adjustable.
The Lower Anvil:
Vertically
adjustable to set            The Lower Anvil:
the amount of                Smaller diameter
pressure exerted             wheel that is
on the metal.                contoured and
                             controls how much
                             the panel is stretched,
                             thus how much crown
                             is created in the
                             panel.
                         Sheet Metal
                       Fabrication Tools
Use of the English wheel




       #1 Anvil    #3 Anvil         #5 Anvil

                              Roller Curvature:
                              Various crowns are available for
                              creating different amounts of
                              curvature.
                                                Sheet Metal
                                              Fabrication Tools
                         ~ 1”
                                       Use of the English wheel
                                ~ 2”




              3/16” Typically            Figure 2     Figure 3
   Figure 1


Tracking:
Each pass must be straight, consistent and run parallel to the
previous pass. The spacing must be the same across the panel to
ensure a smooth curve without any irregularities or flat spots. This
type of tracking will produce a constant curvature over the entire
panel.
                                               Sheet Metal
                                             Fabrication Tools
   Power hammer:
       The Power Hammer is a very large heavy piece of specialized metal shaping
        equipment. While it used to be very popular it is not commonly found in many specialty
        car shops today.
       The rarity today is primarily because of the size and cost of the machine, plus the low
        demand for labor intense coachbuilt cars.
       The power hammer is another very old piece of equipment; mechanized hammers
        were used at least as far back as the 16th century for hammering metal for plow points,
        swords, suits of armor, and horse shoes among other things.
       The earliest hammers were of a Helve type; these were nothing more than a hammer
        head on the end of a lever. The lever arm was raised and then released by a simple
        linkage.
       As time went by, more developing and understanding of mechanical theories evolved.
        Better materials and new power sources were invented and more advanced power
        hammers were developed.
       Because of the noise and the vibrations inventors tried to refine the power hammer,
        one type of hammer used an atmospheric cylinder on the machine. The atmospheric
        cylinder had a sealed piston and ram, when the ram and piston was raised it created a
        vacuum under the piston. When the ram was released the vacuum pulled the piston
        down hammering the metal. This still had vibration problems.
                                        Sheet Metal
                                      Fabrication Tools




                        Power Hammer:
Yoder Power Hammer:                            Fabricated Power hammers are
Yoders are massive cast iron framed metal      now available and work very
shaping machines. Note the deep throat depth   similar to its big brother.
for large panel shaping capabilities.
                                     Sheet Metal
                                   Fabrication Tools
   Pullmax:
   The Pulmax is a universal metal forming machine.
   Pullmax machines have been used in the sheet metal industry for
    many years. The machine's uses are practically limitless.
   When using the proper tooling the operator can do -

   Edge turning
   Flanging
   Shrinking
   Stretching
   Shearing
   Beading
   Slot cutting
   Louvering
   Planishing
                                            Sheet Metal
                                          Fabrication Tools
   Hammer Forming:
       Hammer forming is basically shaping metal by hitting it with hammers,
        mallets, or corking tools over, onto, or into a base form. This base form is
        called a hammer form. Some extra tools that will be helpful are a variety
        of c-clamps, vise grip style clamps, and a vise. Any one, or all, of these
        methods and tools may be used for hammer forming.
       Hammer forming is an inexpensive method of sheet metal fabrication,
        requiring more skill than money. Even if you are making just one part, the
        quality of the part can offset the time spent to make a hammer form, and
        on the other hand, a hammer form can save dozens of hours or more if
        you are building multiple duplicate parts.
       Typically, hammer forms are used on smaller more intricate parts that
        must be quite accurate in dimension and contour. The intricate detail
        work can be carved or milled into the wood or aluminum hammer form,
        then using corking tools the sheet metal can be worked into the designs
        or curves and edges.
                                                Sheet Metal
                                              Fabrication Tools
   Bead roller:
       Uses an upper and lower die through which sheet metal is fed. The dies pinch
        the sheet metal and the metal takes on the shape of the die.
       Bead rollers are available in both hand crank operated and electric motor
        driven versions.
       A large variety of dies are available for unlimited shaping possibilities. Custom
        dies can be machined when special shapes are required.
       bead rolls available for rolling beads in flat panels for additional strength.
       step dies available for creating a step or offset in the metal. Ideal for overlaying
        panels evenly for a lap style weld. Can also be used to produce many different
        body lines.
       Body line roll dies are available for reproducing certain body lines.
       radiused roll dies are available for creating a curved edge on sheet metal.
       Tank roll radius dies available for creating half radii on sheet metal edges.
        When two half radii are welded together a full 90º radius results.
       Three stage hem roll dies available for creating a hem on a curved edge.
                                     Sheet Metal
                                     Fabrication
                                       Tools
   Big expensive tools are not always needed, but
    the do make the job a lot easier and faster.
   The number one tool that you really need is to
    have your skill level very high. With out high skill
    level, the tools will not do much good.
   A good Education could help enhance your skill
    level.
   Try HRI (The Hot Rod School) 