RE: [PSUBS-MAILIST] Acrylic bubble and machining

["Paul Suds" <paul_suds@hotmail.com>]

Wade, it's Paul or Suds. You can drop the mister, I'm not that old, ha. Are 
you doing this for a University engineering project?? There's a bunch of web 
sites for building the human powered  wet subs. As far as building the dome 
hatch, please give me more particulars. If this is a hatch in the front of 
the sub, then laminar flow is a consideration. Usually a bullet design is 
very good and very easy to make. For this you can use gravity, rather than 
vaccum. With gravity, the optical clarity is maintained to some degree and 
you don't have to worry about polishing your male side of your mold cavity. 
If this will be a one time human powered racer, I would use acrylic rather 
than polycarbonate. Either way you will need to design a simple oven. Again 
you have to provide more details. What material are you buildign the hull 
out of, fiberglass?? What will the flange of the hatch be made from, metal, 
fiberglass, or do you want to make in integral to the acrylic, i.e, acrylic 
flange?  how do you plan on fastening it to your hull?? Your overall design 
constraints and specifications that your team has established will dictate 
your approach. I assume that cost and mass are a consideration, as well as 
overall speed. Are there mandated safety specifications for the hatches?? If 
so what are they? I'm sure if you are specific enough, you will not only get 
help from me but lots of help from the other members on here. Thermoforming 
can be very easy and rewarding or very difficult and frustrating. Hope i 
haven't overwelmed you with too many questions...Suds
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