User:Remi Scarlet/Blog/FurutakaKaiNiCosplay/Day4

Day 4

Date: 5/25/15
Time spent: ~1.5 hours

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So outside of actually just making a working super arm cannon that characterizes Furutaka kai ni a lot, one of the difficulties of making this cosplay is the black cannon that Furutaka has.

Mechanical joints and whatnot. One of the challenges with Furutaka kai ni's cosplay.

The problem with this part are the mechanical limbs and joints that connect them. So to actually make this with a mechanical shop isn't too bad since you can machine your individual parts and whatnot. Unfortunately, I'm not a mechanical engineer and even though I do know my basic CAD and whatnot, I have no access to equipment for just machining out my parts (Which would have made life a lot easier, albeit more expensive).

So the majority of today's "work" was actually spent just lying on my bed and staring at the ceiling while thinking "How the fuck.". After about 10 minutes though, I suddenly got an idea. Since I already had plenty of PVC pipes lying around and it was easy enough to go buy more, I decided I would try to tinker around with the PVC piping to see if I could emulate hinge and pin joints with them. After hacking away at PVC with my saw and lighting the pieces on fire over my stove, I finally ended up with something like this for a hinge joint.

PVC and screw solution to the hinge problem

So this is actually pretty beautiful in my opinion, the fast prototyping and resultant aesthetic lacking aside. So the amazing this about this is that it basically serves every function I need it to do and that I can actually make it a "stiff" joint, as in I can move it around if I tried but once I let go, the joint will stay "in-place". The "stiffness" can easily be achieved by adding something to increase friction such as adding a layer of duct tape at the connection point of the two pipes and tightening the bolt on the screw a lot. By double nutting the screw, this would ensure that the nuts and resultant pressure wouldn't come loose.

With this solution, I figured out that I can actually make the limbs and hinges work very nicely for a ridiculously cheap cost. Compared to CADing and machining out the parts, just grabbing some PVC pipes, screws and nuts might as well be free by price comparison. The only part I haven't covered here is the pin joint. While the construction of a pin joint itself would be very easy by simply making the same U cuts in the thicker piece of PVC and laying the thinner piece in the U shaped crevice, I would still need to figure out some method of "stiffening" this form of joint. That said, I believe with some clever application of friction-inducing materials and more tightened screws should solve the issue here as well. I'll obviously make updates on this subject once I have a chance to head to Home Depot at the end of the week and go buy more materials.

So with that, here are a couple of photos demonstrating stuff.

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  "Example" of how the hinges would work out. Front of the fat tube would be where the black cannon goes.

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  Flattening the flap of PVC via heating with fire and rolling flat with another, thinner, PVC pipe.

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  Mostly flattened example.

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  Closeup while not connected via screw.