webhead said:
I though about making a wire mesh first (from something like chicken
run fence wire mesh, thin wire big gaps)
If you want to go that route there are better types of mesh available. Try a type used behind ventilator grilles to prevent rodents and bugs from entering for instance. There are several several different gauges and gap sizes available.
It's not that easy to get such a design nice and symmetric though, at the very least you should consider adding some ribs and other braces for it to keep its shape during lay-up.
webhead said:
.. and drape my fiber around it in narrow ends, much like handlebar tape.
Although that would work it would lend itself to unnecessary weight in the finished item. In FG manufacture you need a certain overlap for good adhesion between layers, and that method would give more an excessive amount of overlap. As big as possible w/o wrinkling is the ticket.
And I still think you'd be better off sculpting your helmet out of Styrofoam, sealing the surface against solvents and then doing your layup on that. It'll retain its shape far better and give you a better shot at coming out with a symmetrical product.
webhead said:...For instance I'm missing info on the usable polymers. Is an epoxy two compound resin the only polymer that's sufficient in terms
of structural rigidity?
Rigidity is a joint characteristic of material properties and design features. There are lots of stuff out there that you can build strong enough components out of as long as you adapt the wall thicknesses, exterior dimensions (and perhaps internal bracers as well) to suit. But if you want a strength/weight ratio that makes it worthwhile to leave alloys behind then you're pretty much limited to the exotics.
webhead said:...I've known people to construct a boat hull
with sheets of fiberglass and polyester coatings, sanding and
smoothing it out in between layers but a boat hull is not a thin
handlebar or frametube.
apparently you've never seen a racing yacht up close...
But the thing is simply that for most people the weight/strength ratio of the material that goes into a boat isn't critical enough to merit the extra cost of going to CF and epoxy. OTOH FG and polyester can easily be shaped into double-curved surfaces, which is a feature that is quite desirable in boat building.
webhead said:...I'll be sure to wear gloves and long sleeves when I should handle fiberglass.
While that is a sensible thing it isn't the right priority. First protect your brain, then your hands. Get a GOOD mask, one capable of handling solvents and hydrocarbons. A simple dust filter is OK for the sanding but it's nowhere near enough for the actual resin work.
