Saturday, February 7, 2015

Raygun V

Have a drawing for concept group #2 now. I just could not get the kind of boomerang-and-rod look I was after in a handgun. I think it requires a longer weapon, two-hand grip, with or without stock. For the shorter pistol lengths, acrylic furniture seems to work out better than MDF (although I haven't entirely ruled out aluminium sheet stock).

Design-wise, I miss the bounce and fun and exuberance of the other designs. And I also pretty much failed in capturing any of the Art School and Proud of It feeling of the Barbarella movie props.

The flat industrial look comes from the materials concept; the turned acrylic emitter is framed by symmetrical fingers in 1/4" acrylic, with the grip, trigger guard, and fin being extensions of these parts. It might be improved by moving to metal for the fingers, making the grip plates in CNC metal, and adding glossy red or black insulator rings between body and emitter.

But it is enough to move to trial analysis. The acrylic sheet parts are a quick laser job. The whole thing should be roughed out in CAD anyhow. The barrel rod is turned acrylic, which can be done on the metal lathe.

If there are internal electronics, then the rear cap should be practical. The drawing suggests it screws on -- hence the knurling -- but no reason it can't be magnets. I'm not eager to start threading on the lathe!

The grips are rounded and thickened with what is indicated as a black rubbery compound. Not sure what this is. Sugru would do but be expensive. Might be able to carve and sand urethane matts. Or perhaps print; the starburst is complex enough that it may make most sense as a 3d print, rather than trying to hand-carve a shape in clay then cast it.

I also haven't any solution yet for the trigger, which should probably be sprung and in any case is likely practical.

Because of the dimensions of some of the stock, and the need to print or mold some elements, materials cost is around a hundred even before adding electronics. CAD phase is 2-3 days, lathing a couple of days, assembly and clean-up finishes off into a second week.

I don't have a developed sketch for the "Hairdryer" (concept group #1) but there's enough to work on the essential problem. There's a good dozen methods I could use to form the sculpt (not counting hybrids and combinations). So far, though, I only have three strong ideas for making it sturdy enough for convention carry.

Slush-casting is the obvious one. But we're talking 60-100 bucks worth of silicone to cover that size of an object. Shell mold is possible, I suppose. In any case, this seriously pushes the budget.

Second alternative is to glass it. Resin-coat, then dig away the sculpt to provide some interior space. It isn't entirely destructive -- one could still make a casting off the finished piece. It also isn't as neat or as strong, and is a lot harder to work with in putting internal electronics in (I think!)

Third alternative is vacuum form. This might include a glassing stage just to make the master tough enough to take the 14 psi of the pulling process. And then the pull needs to be cleaned up and reinforced, as per my Instructable on the subject.

Out of all of them, glassing is the lead contender for coming in under budget. It is also, oddly, the most labor-intensive; because as time-consuming as cleaning up a pull is, doing all this work on the master is a lot tougher. I speak from experience.

Perhaps what needs to be folded into all of these, but this one in particular, is if I want to leverage economies of scale; intend from the start to make multiples and offer them in an Etsy store or something after the original order has had a chance to shine.

After working on it a bit more I think the best reinforcement also partial dictates construction. Cut two identical midline pieces from 1/8" MDF. Build up the shape in blue foam, tooling foam, or similar -- CNC'd if I can find a material well-suited to that. Carve, skin, sand traditionally. Then separate at the midline to create the two bucks for vacuum forming.

Oh, and Concept Group #3 faces the same class of problem. How to get a firm surface, made worse by the need to be thin and strong enough to support internal mechanism. I had originally thought of using a laser-cut acrylic framework that supports the sculpted elements, but that was before my research turned up that the basic shape is cylindrical, not square! But perhaps this is still plausible -- especially with CAD as a tool to plan the acrylic pieces...

One last interesting bit. I think this one really does want to be hand-carved. If there were more than one, each would have a unique personality.

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