You’ve just described the casting
method which is indeed used, except no balsa. See Stachiw’s book for
pictures of the molds and a more detailed description.
-----Original Message-----
From: Akins
[mailto:lakins1@tampabay.rr.com]
Sent: Wednesday, February 23, 2005
11:54 PM
To:
personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST]
uniform? acrylic viewport thickness
I'm just curious about something. I
know you can make a plywood sheet with a cutout and a frame that holds the
edges of the acrylic so you can heat and blow it up.
But why not just make an inside form
that is the exact contour of the inside of the acrylic bubble that you want,
maybe out of smooth balsa or something. Then make a
corresponding outside form for the
bubble. Then stack the outside form over the inside form and the airspace
inside would be the exact size without any thinner points all
around. Then just pour in the molten
acrylic and let it dry. Although this would require basically two forms stacked
on top of each other, wouldn't this do away totally
with any problems of the bubble
having thinner spots? Just a thought.
----- Original Message -----
Sent: Wednesday,
February 23, 2005 10:45 PM
Subject: Re:
[PSUBS-MAILIST] uniform? acrylic viewport thickness
Question... If you heat
the acrylic evenly with several heat lamps, and leave the center just a LITTLE
bit cooler than the rest of the project, Would the apex of the bubble
retain more of it's thickness and result in more even thickness over the whole
dome? This might be accomplished by a ring of lights over the project.