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Star Kustom Shop Bubbletop Fabrication - BubbliciousBubble Blowing 101 From the January, 2011 issue of Rod & Custom By Dakota Wentz
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In 1960 Darryl Starbird unleashed a whole new kind of custom upon the world, the futuristic dream custom. His exemplary creation, dubbed "Predicta", was like nothing seen before. It was innovative, outlandish, and, quite frankly, out of this world. Inspired by the aerospace movements buzzing around Starbird's hometown of Wichita, Kansas, Predicta featured such advancements as dual controls, stick steering, cockpit-styled interior, and a television. Granted, all of these features mesmerized bystanders and onlookers, but what really overwhelmed audiences was the clear Lucite bubbletop. It was the kind of forward thinking only seen in comic books and the vivid minds of science fiction. Yep, this fresh idea of a bubbletop spiraled the hot rod world into a bubble frenzy. Using 1/2-inch electrical... Using 1/2-inch electrical conduit, Darryl Starbird begins forming the perimeter of the bubble to the contour of the body. For this build it's a simple semi-rounded D shape. (Full bubbles require conduit around the entire opening.) Remember, the bubble will take the form of the inner diameter of the conduit, so design accordingly. Here we are 50 years later and bubbletops still create the same shock and awe reaction in the rod and custom world. (On a side note, a big part of that is because the jet packs, laser guns, and flying cars predicted years ago have fallen ... let's just say shorter than Britney Spear's skirt!) Their uniqueness and creativity still captivate and draw in audiences, yet what intrigues viewers even more than the clear domes themselves is the mystique of, "How'd they do that?" For starters, bubbletops are one-off creations designed for each vehicle. The process begins by creating a tool based around the perimeter of the bubble. Once the perimeter of the bubble is determined, the height is designed into the tool. Next, a piece of Lucite plastic is baked in an oven and placed under the tool. (By the way, urban myths about bubbletops and pizza ovens are exactly that, myths. Lucite tops require large sheets, beginning at 6x6 feet and counting; therefore Luigi's Pizzeria oven is outta the question.) Once heated, the Lucite and tool are clamped together, and air pressure is used to free-blow the Lucite sheet into its bubble form. Once the perimeter was set,... Once the perimeter was set, we transferred the pattern of the ring to 3/4-inch plywood. Using a jigsaw, the plywood was cut accordingly. Even though the "Ultra Truck" isn't a full bubble, an entire bubble needs to be blown to keep the shape of the bubble consistent; therefore a duplicate plywood pattern was cut. Contrary to what some may think, vacuum forming isn't the way to go. Vacuum-forming Lucite will give one the desired shape, but that's the extent of it. In order to take shape the Lucite must be pulled down into a mold, and once the Lucite hits the buck its impressionable state will take the form of the surface and produce all kinds of wrinkles, waviness, and distortion. (Imagine looking through a square block glass wall at a '60s diner.) Basically, the optics of the bubble are ruined during the vacuum-forming process. For that reason free-blowing is the only way to go. It not only blows the desired shape, it also maintains the optics. The last step of creating a bubbletop is trimming the bubble and creating a ring. When it's all said and done it's not exactly rocket science, or is it? You be the judge! The next step in creating... The next step in creating the tool is to butt the ring patterns together and secure them with 2x4s. Shedding some light in the form of a Kodak moment is Star Kustom Shop and the innovator himself, Darryl Starbird. One of Starbird's creations from the '60s, the "Ultra Truck", is in the Star Kustom Shop for a new bubble. On the ensuing pages we'll dig into the bubble process-which is the same process Starbird designed and engineered clear back in 1959-by creating a new bubble for the Ultra. The process will be revealed from start to finish; including creating the form, building a tool, blowing the bubble, and trimming and fitting the bubble. Yep, the method of mayhem behind the bubble will be uncovered Perry Mason style!  Bubbletops are free-blown,...  Bubbletops are free-blown, which means they can be blown to the desired height. Measuring from the base of the bubble to the peak in the canopy gives us our height. Normally the height would be set to where one would want it.  The height for this bubble...  The height for this bubble wound up being 17 1/2 inches, therefore the framework around the tool was built to that height. From the top of the plywood to the bottom edge of the upper 2x4 is 17 1/2 inches.  Ensuring the bubble is blown...  Ensuring the bubble is blown smooth, Starbird sands the plywood ring. Also, any cracks-like the butt joint of the two patterns-are filled with wood putty. The base of the tool needs to be air tight, or the bubble will lose air pressure during the blowing process and the shape may not take the correct form.  Darryl uses Plastic Fabricators,...  Darryl uses Plastic Fabricators, in Tulsa, OK, to blow his bubbles. The first step for Jack and the gang is to create a blowing base for the bubble tool. From there the Lucite plastic is placed in the oven (the giant-sized green box in the background) and heated at 350 degrees until the perfect elasticity is achieved. Once the temp is reached, the plastic is pulled from the oven and placed on the table.  The bubble for the Ultra is...  The bubble for the Ultra is as simple as it gets, it's just a true bubble that gets cut down to size. For more complex bubbles, like the bubble on Starbird's "Forcasta", a little more engineering goes into the tool. Here is a tool for a shaped bubble. Notice how the opening at the rear of the tool is cut to form a double-bubble effect. To set height and add contour, a restrictor is placed down the middle (note arrow). When the bubble is blown it will rise up and hit the restrictor. As the bubble rises it will blow up and around the restrictor giving the bubble its shape. A tool like this will give the double effect like the Forcasta's.  Next, the tool is placed atop...  Next, the tool is placed atop the Lucite and clamped to the table, and once clamped, air pressure is blown into the bubble. Here you can see how the bubble is flowing up the restrictor and tapering off into a double-bubble effect. Once the Lucite reaches the end of the restrictor the pressure will be stopped and the bubble will have reached its full shape. As for the bubble on the Ultra, once the middle point of the bubble comes within 1/4 inch of 17 1/2-inch mark (the upper 2x4), the pressure will be stopped.  With the bubble removed it...  With the bubble removed it was time to start trimming. Some bubbles require the full bubble, as pictured. Yet, the Ultra Truck is only half a bubble with a sheetmetal canopy making up the rest of it. Using a router outfitted with a 3/16-inch straight-cut bit, Starbird cut the bubble down the middle.  The router works great to...  The router works great to cut the bubble, but it doesn't leave the cleanest cut. Therefore, a 7-inch grinder is used to create a clean, even edge. The grinder also works best when shaving minimal amounts off the bubble for a precise fit.  Once placed on the truck it...  Once placed on the truck it was clear a bit of trimming was in order. Using some tape the trim marks were made. (Also, due to the nostalgic factor of the original top, we're creating the bubble to fit the canopy, however, normally the bubble would be trimmed accordingly, and then the canopy would be made to fit the bubble.)  All bubbles require a ring...  All bubbles require a ring around the perimeter. Using 1/2-inch conduit, I created an outer ring following the previously made inner ring.  Sheetmetal is used to skin...  Sheetmetal is used to skin the ring. With the bubble still in place the skin was tacked throughout the ring. Once everything was tacked together the bubble was removed and the ring was welded solid.  Every bubbletop needs an actuator...  Every bubbletop needs an actuator to lift the canopy. Electric screw jacks or linear actuators work best. One, they supply ample power to lift the canopy; and two, unlike air or hydraulics, there is no chance of the top "bleeding" down when left up. The actuator shown here is the Ultra's original. A great place to pick one up nowadays is from AutoLoc.  The last step is to dress...  The last step is to dress the ring. Starbird dresses the ring on the car; therefore the fitment can be narrowed down for an exact match to the body. Once the ring is dressed, it's primed and then later painted. All the while, the bubble never leaves the ring.  There you have it, Bubble...  There you have it, Bubble Mania 101!  Black urethane window-weld...  Black urethane window-weld is the easiest and safest way to secure the bubble to the ring-Lucite cracks very easy when drilled or screwed. When gluing the bubble in place it's important the ring is lying in its resting position. Gluing the ring off the car is most likely going to result in the ring being in a bind and not lying properly.
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