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Hirobo Bell 47G (GS) |
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Hirobo Bell 47G (GS) |
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Fuel tanks (Part 1) |
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The scale fuel tank covers included in the kit were not considered to be appropriate for this model. This section details the work involved to produce replacement items. |
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The first step was to modify the bottom half of the tank; namely to fill the Hirobo item with epoxy and remove the ribbing and extend the height. The original vac-formed item is on the left with the modified pattern on the right in gloss red. At this stage the pattern would not survive the extreme heat of a vac-form machine so the next couple of steps detail how an epoxy pattern was produced. |
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The pattern was first suspended in a bath of silicon rubber. |
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With the silicon dry the pattern was removed revealing a female mold prior to the high temperature epoxy being poured in. |
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The top half of the Hirobo item was suspended in a Plaster of Paris bath so that it would not deform in subsequent stages. Once the plaster was dry the ribs and other detail were filled in with plasticine (red). |
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Removing the epoxy ruined the original Hirobo item as expected. Minor filling was required to make a smooth pattern. |
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The modified pattern went through the same process to make a female silicon mold. |
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The two silicon molds were then filled with epoxy specifically designed for making patterns to survive the high temperatures of a vac-form machine. Here are the two patterns having been pulled out of the silicon baths and in situ in the vac-form machine. |
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A few seconds later the first items were produced… |
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… and they just need trimming prior to installation. |
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Webmaster: John Neasham |
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