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Old 12-02-2012, 11:14 PM   #15
Bill G
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Thanks Paul. I've been keeping an eye on your Astro Hog build also, which turned out really well.

One of these days I'll have to build a vacuum molding machine, as the hand pull method produces less than perfect parts, when making larger parts. For this one, it wouldn't have worked however, as the mold is a sheeted foam core, which would melt. Since I didn't want to wait for a trip to the LHS to buy solid balsa block, I sheeted a sculpted foam mold with 1/32" balsa. The outer perimeter of the non sheeted surfaces of the foam core have balsa frames epoxied to them, which are used to glue the sheeting to, using CA. The sheeting provides enough heat protection to prevent the foam core from melting, with the hand pulled, heat gun method. The mold turned out well, although the hand pulled parts seem to always have some imperfections in one area or another. Version 2 worked out well enough to deem useable. The canopy will probably be mounted on a frame, so that it can be removable for batt/ gear access. I can always make another, if done that way. Lessons learned from the past have shown that it's good to make a large canopy removable, especially true on planes with nose glass such as my AR234 that's on canopy #5. It can be easily replaced if damaged, versus having to cut it off and replace, re-trim, etc. At lest this plane has a solid nose under the glass, reducing the chance of damage.

Since the lousy sheet plastic costs a fortune at the LHS, I may have to collect a few clear 2-liter bottles from neighboring recycle bins. I've seen a method where the bottle is slipped over the mold, and then pulled downward with a stick slipped inside the bottle, while heating the bottle with a heat gun. The bottle should be reasonably close in shape to begin with, so it may work well.


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