©Strands of History At trade shows and craft fairs, we get so many questions asking how we fabricate our furniture, artwork, and the 4-inch and 12-inch memento pieces made from the original suspender ropes from the Golden Gate Bridge. We thought describing the process would be the perfect blog subject. So, this is how we do it!
Introduction
For ease of handling and storage, our inventory is made up of 11-foot sections of the original suspender ropes from the Golden Gate Bridge. These historic steel ropes are 2 11/16th inches in diameter and weigh approximately one pound per inch. In addition to being heavy, the original suspender ropes are flexible (they have an arc radius of 30 inches). It always takes two people to carry a length of suspender rope, if you pick it up in the middle, the ends touch the ground. So at 11-feet, we’re wrestling 135 pounds of bending steel rope.
Two thin strips of strapping steel stabilize each end of the suspender rope. These stabilizing strips maintain the lay of the wire rope. Each suspender rope is made up of 229 individual wires, and all but one of the wires has inherent torsional tension. That is to say, 228 wires are under stress to maintain the rotational twist of the steel rope. If the stabilizing strips were to come off, the wires in the rope would spring outwards with a lot of energy. Enough energy to knock a grown man backward.
Step 1: Cleaning
The first step to transform these original suspender ropes from the Golden Gate Bridge into art, furniture, or souvenir pieces is to remove all the old lead-based paint and accumulated debris. The group we contract to clean the suspender ropes had never worked with such unique material. Trying to manipulate these flexible steel ropes while directing a high-pressure stream of abrasive material (also referred to as sandblasting) turned out to be very labor-intensive. Even after hours of work, the ropes still had a lot of leftover paint. The guys came up with a plan to start the cleaning process by heating the suspender ropes to 500°F, which makes the remaining original lead-based paint and debris more friable. Next, the ropes go into a special abrasive blasting chamber that contains all the material removed by sandblasting; this results in a quite clean piece of steel. Even with all that work, there is still some original paint stuck in some places. For those tough, stuck on areas of paint, we use dental tools to remove any remaining paint. The outcome is a piece of galvanized steel suspender rope that looks nearly new.
Step 2: Stainless Steel Bands
Our finished sections of the original suspender rope from the Golden Gate Bridge have two stainless steel bands that when crimped using our custom hydraulic press, secures the individual wires in their identifiable wire rope lay. We pre-cut lengths of stainless steel tubing to meet the demands of a particular project. We start with 20-foot lengths of 3-inch stainless steel tubing that we cut with a bandsaw. For each project, we cut a different measure of stainless steel tubing that accounts for the metal lost with each cut throughout the process. The bandsaw blade is 1/16-inch width, and the chop saw blade is 3/16-inch width; for smaller sections of rope, the stainless steel band has an additional midpoint cut. After cutting, all of the stainless steel bands are deburred and finished smooth before placement on the suspender rope.
Step 3: Welding
Before loading the original suspender rope from the Golden Gate Bridge with the stainless steel bands, we remove the thin strips of strapping steel. To safely remove the strapping steel and maintain the lay of the wire, we need to weld together the ends of all 229 individual wires. First, we secured a length of suspender rope to a steel track. We use a series of clamps (cuss words and sledgehammers are optional) to ensure that the suspender rope is as flat as possible. A flat, stable suspender rope makes all of the subsequent steps easier as there are no bends that could alter measurements.
The inherent complicating factor is that welding galvanized steel produces toxic fumes that are incredibly dangerous. In addition to wearing respirators, we use big fans to improve ventilation. Inhalation of zinc oxide fumes can cause “metal fume fever”; even mild exposure induces headaches, wicked headaches.
While the weld is cooling, we test to see if a stainless steel band can slide onto the suspender rope. Often a few of the wires need to be ground down to pass the stainless steel bands onto the suspender rope.
Step 4: Crimping
After the weld has cooled, we remove the thin protective strips of strapping steel and load the appropriate number of stainless steel bands onto the original suspender rope from the Golden Gate Bridge. We typically load enough stainless steel bands to make table leg lengths in addition to 12-inch sections and 4-inch sections. In this image, we have a large production order for a retail shop specializing in unique San Francisco souvenirs, so they’ve placed an order for 4-inch pieces of suspender rope.
The stainless steel bands are crimped into place using a custom-built hydraulic press with six pistons that we take up to 7000 pounds of pressure (the crimper). When we took over the business, people would come into the shop and ask, “What’s that big thing?” while pointing at the crimper. So, one day Mary decided to christen it “The Big Thing,” and painted on the name. To facilitate the placement of the stainless steel bands in a standard fashion, and not to have to use a tape measure each time, we cut sections of steel to standard lengths. For the popular 4-inch Golden Gate Bridge Souvenirs, our unit of measure is one “Tom” after our long-time friend and business partner who passed away a couple of years ago. For the equally popular 12-inch memento, we use a unit of measure called a “Jose” to recognize how much we learned from our friend Jose, who taught us many of the intricate details of the fabrication process.
Step 5: Cutting
After the original suspender rope from the Golden Gate Bridge has all of the stainless steel bands crimped in place, we use an engine hoist to move the loading track and suspender rope over to the cutting area. While still elevated on the hoist, we adjust the height of the legs so that the loading track is level with the cutting deck of the abrasive chop saw. We use a 10 Horsepower, 3-phase chop saw explicitly designed to cut wire rope, fitted with a 14-inch abrasive blade. Because the saw is tremendous and throws out a lot of sparks, debris, and smoke, Bob is the operator. From this point onwards, we are both wearing respirators, eye protection, and ear protection. To communicate, we use hand signals; the universal language of hand gestures work well in the shop.
The rope is fed into the cutting chamber and tightly held in place with a foot-operated chain clamp. Before cutting the 4-inch pieces, we mark the mid-point on each stainless steel band, the suspender rope is adjusted so that the blade hits right on top of the mark, and the rest of the rope is further clamped down to the track with C-clamps to keep it as straight as possible. Each abrasive blade lasts for no more than about five cuts. The blade is switched out, and the process begins again. We’ve looked into various other methods for cutting the ropes, but thus far the abrasive chop saw is the best method. Band saws, water jet cutters, and plasma cutters start to cut through the 229 individual wires, but as they get about a third of the way through, the cut wires start vibrating too much. As one of those operators said to us, imagine what it would be like trying to cut a handful of toothpicks with a handsaw.
The first cut off a new blade is always clean. As the blade erodes, the quality of the cut does so too. The suspender rope is turned to cut all the way through. Often this leads to slight ridges that must be ground down in the next stage of fabrication. When the cut suspender rope pieces are cool enough to handle, they are blown out with compressed air to remove the disintegrated blade and metal debris.
Step 6: Grinding, Finishing, and Polishing
The next stage of fabrication is the vertical grinder. We start with 36 grit discs to remove any ridges and deep cut marks left by the abrasive saw blade and to deburr the cut edges of the stainless steel bands. Then we proceed to 80 grit to remove any remaining blade marks and the lines from the 36 grit disc.
The piston heads on the crimper sometimes leave “shoulders” that need to be smoothed out. The next stage uses hand grinders to progressively finish and polish both the stainless steel bands and end cuts to a smooth finish. We use a combination of 80, 180, or 320 grit sandpaper, as well as medium, very fine, or superfine 3M finishing discs depending on the condition of the cut end or the stainless steel band. After finishing, we polish the sections of suspender rope on a 12-inch 320 grit flap wheel. By far, these parts of the fabrication process are the most time-consuming.
The historic steel wire in these ropes is high carbon steel, and exceedingly hard, so it takes a lot of patience and many steps to give it a smooth surface. From the raw cut end to having the piece ready for polishing, it typically takes from 45 – 60 minutes per section. The challenge for us through these stages is arm, wrist, and fingers fatigue. For the 4-inch piece, one hand is manipulating a five-pound piece of steel, and the other hand is leveraging a four-pound grinder. That may not seem like much, but try doing it repetitively for hours. Bob listens to music while he works, while Mary opts for podcasts or audiobooks. Sanding and polishing aren’t too monotonous, however, because each section of rope is unique, and you can’t help but think of the people that made it, or installed it, or worked on the bridge, or those that maintained it. It is interesting to handle it so much and learn its varied character.
These smoothly finished sections are cleaned again with compressed air and covered until the next stage of fabrication: polishing and waxing. The flap wheel puts a beautiful smooth finish on both the cut ends and the stainless steel bands during the final sanding stage. The pieces are then coated with two layers of metal wax on a 12-inch double sisal wheel to create the bright shiny finish on both the wire ends and the stainless bands.
Step 7: Painting
Each section of the original suspender rope from the Golden Gate Bridge goes through a final cleaning with compressed air, then washing with denatured alcohol or acetone. Each piece is ready for painting or clear coating. We initially used an airless sprayer in our paint room, but the process of taping the stainless steel bands and prepping the sections took too long. We now hand paint all sections. We use a Direct-to-Metal Alkyd Enamel manufactured by Sherwin-Williams that allows direct application to the bare galvanized steel. The color is customized to match the current paint on the Golden Gate Bridge. The Golden Gate Bridge, Highway and Transportation District supplied us with the color formulation. We apply a minimum of two coats of paint on each section; then the stainless bands are carefully hand-cleaned to remove paint smudges.
Step 8: Packaging
After the paint has cured, we affix the Strands of History logo medallion to the piece using copper wire held in place by a crimped metal button embossed with “GG.” The section of original suspender rope is then securely wrapped onto the custom-milled red oak base, so it doesn’t shift during shipping, we pack the boxes with brown crinkled paper to prevent damage, and place literature in the box that describes the history and characteristics of the suspender ropes, a Certificate of Authenticity attesting that this section of rope is from the original vertical suspender ropes on the Golden Gate Bridge, and a thank-you note from us.
