Need Advice for Mechanism, first prop ever.

Champsquire

New Member
Trust me, that title scares me just as much as it does you.

I've recently found out that I can feasibly (read: barely) make it to this year's Dragoncon! As such, I decided that making a cosplay is some form of a rite of passage, and I have to. Besides, the majority of my group will be in RWBY cosplays as well, so I'd be that one weirdo following around a bunch of scythe-and-gun-infused-weapon-wielding badasses.

My character of choice is Jaune Arc, a (somewhat) typical swordsman, wielding the topic of this post; a sword and shield pair known as Crocea Mors. The sword is a standard longsword, and I am decently confident in my abilities to make it look even halfway decent. My issues come with the shield, which serves as a sheath for the sword, and the outer fins expand straight out in panels from this sheath to form a heater shield.

Now, as I'm an overzealous engineering student with access to a 3d printer, I want to make this thing function. With some research, I found drawer slides to be a decent way to have the shield panels expand out, connecting solidly at the very outside edges. My only issue is that I am having difficulties figuring out how to attach and consolidate the panels inside the piece, with the drawer slides connected. I would be using 6 inch drawer slides that expand to 12 inch. (~150mm -> ~300mm)

Pictures included, as well as a scale sketch of the shield, drawer slide inserted for reference.

Thank you so much for your time!

Crocea Mors RPF snip.PNG
Crocea Sheath.png
CroceaShield.png


UPDATE: Just had a moment of clarity, as my main issue is that the drawer slides mounted horizontally will not extend far enough, and make the sheath too wide. Could they be mounted on pivots in the main body to allow longer slides to be used, and push out farther?
 
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Duncanator

Sr Member
I love a cool mechanical challenge!

I'm not quite sure what you're trying to make it do. From your description and the pictures, it sounds like it starts as a somewhat thick sheath that expands to a shield shape once the sword is drawn?
That does sounds tricky since everything kinda occupies the same space. Sounds like animation magic! the drawer slides will add even more thickness to the sheath/shield.

You could also try having the wings (for lack of a better term) pivot out from either side of the point. They will follow an arc path up top, so the drawer slides won't work. You could have them overlapping each other right behind the front panel of the sheath, so that when they deploy, there is as little offset as possible. Kinda like a fan.
 

Champsquire

New Member
I love a cool mechanical challenge!

I'm not quite sure what you're trying to make it do. From your description and the pictures, it sounds like it starts as a somewhat thick sheath that expands to a shield shape once the sword is drawn?
That does sounds tricky since everything kinda occupies the same space. Sounds like animation magic! the drawer slides will add even more thickness to the sheath/shield.

You could also try having the wings (for lack of a better term) pivot out from either side of the point. They will follow an arc path up top, so the drawer slides won't work. You could have them overlapping each other right behind the front panel of the sheath, so that when they deploy, there is as little offset as possible. Kinda like a fan.
I'm honestly perfectly okay making the sheath and shield bit separate, if need be, and most likely will have to. (Should have mentioned that in the main post, woops.) The thickness is also something I would like to minimize, but have no problem making it a bit inaccurate to the show in order to make it function.

I've been offered the idea of a fan-like design a few times, but I also don't necessarily see how to make it happen without looking a little wonky. Perhaps I'm being a bit thick at the moment though.

Also, it definitely is animation magic, which is why most people go for a folding panel system on the side, or an entirely detachable shield separate from the sheath. However, I'm stubborn as hell. :p
 

Sean

Sr Member
RPF PREMIUM MEMBER
What about two collapsing sleeves on each side with two wire frames shaped to your two sides. Joined at the bottom with pivot screw. And pushes out from the top to fill the sleeves. Kinda umbrella like. Just somthing off the top of my head
 

Champsquire

New Member
What about two collapsing sleeves on each side with two wire frames shaped to your two sides. Joined at the bottom with pivot screw. And pushes out from the top to fill the sleeves. Kinda umbrella like. Just somthing off the top of my head
My only issue with the pivoting idea is I don't see how it would all collapse into the sheathe's body. I like the collapsing sleeve idea, but I'm not entirely sure how I would pull such a feat off.

Could the x-shaped pivoted drawer slide method I mentioned in my update be feasible? It would allow for longer slides to be used, allowing me to reach the distances I'm looking for.
 

Sean

Sr Member
RPF PREMIUM MEMBER
My only issue with the pivoting idea is I don't see how it would all collapse into the sheathe's body. I like the collapsing sleeve idea, but I'm not entirely sure how I would pull such a feat off.

Could the x-shaped pivoted drawer slide method I mentioned in my update be feasible? It would allow for longer slides to be used, allowing me to reach the distances I'm looking for.
My Idea wouldn't have slides. The wire frames on each side would just be atached at the bottom of the sides and able to pivot just a bit. The top part of the two wires would hold the Inverted L shape and just spring outwords from the top. They could be attached at the same point and pushed outward with one motion. Sense the side of your sheeth has nothing on It. You could make that doors to hold the two sleeves Inside the two sides.
 

clonesix

Sr Member
This is Cartoon Magic, and not likely doable in the physical world.

My thoughts: Choose one or the other. You can have a sheath or a shield, but not both. With some imagination, you might be able to fake it cleverly enough that other cosplayers will recognize the character.

For reasons stated above, all the parts occupy the same space, and zero thickness material doesn't exist, and thin material isn't very strong.

At first glance, my only idea is to wrap the shield around the sheath, and once the sword is pulled, the shield would unfold. If I look at your drawing and do some math, your 11.5" of half the shield with will wrap around the sheath with 2.46" excess around the back (on each side). You can adjust the width of the sheath and shield to match a little better, but there will always be seams where it folded.




Last note: You are building a COSTUME and not a COSPLAY!

Difference: Costume = Noun (person, place, or thing)
Cosplay = Verb (creates action)

Hence: You are building a COSTUME so that you may COSPLAY with your friends.




Yeah, I like costuming, but I love good grammar!
 
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propmaster2000

Sr Member
Maybe, if the shield was made of a light weight fabric, which is pleated or a stretch type fabric and there were several spring steel rods forming a fan shape, the ends of the rods could be pressed into "angle cut holes" in an aluminum block (at the bottom) at such an angle that the "fan rods" would want to hold the fan in the open postion all the time.
The fabric itself could be stitched to the rods in various spots and be painted to suit the need.

With a "cable and block" set up, the sword could then be pushed in, pressing on the block & cable setup, pushing the cable down (pictured yellow) on two small bearings, thereby pulling the sides of the fan inward, allowing the stretch fabric to re-assume it's original size inside the sheath.
Just thinking out loud with pictures. :)
This of course is not to scale or even the right shape.
It's only a proof of concept.

sword sheath-shield.jpg

.
sword sheath-shield 2.jpg

.
BACK
sword sheath-shield 3.jpg
 
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Champsquire

New Member
Champsquire,
Have you settled on a procedure to accomplish what you ask?
My apologies! I have been a little busy with college as of late, and couldn't get back around to a reply.

Propmaster, I really appreciate the idea, I never thought about making the shield out of fabric, which is ingenious! Also, thank you for the very clear model, it makes imagining how it all would come together and function infinitely clearer.

At the moment I'm tossing up some ideas and I'll be sure to update you all when I decide on the mechanism I choose.
 

pastadude

Active Member
RPF PREMIUM MEMBER
The closest functional thing I can even think of like this would be the remote control batarang from Batman Returns, and that... would not function for something like this. The fabric popout idea might work, but is very zealous... but then again, who am I to say it can't be done? I'd offer my vote in heading in that direction, and doing a popout fan-style sheath. But definitely keep us updated with if/how you pull it off!
 
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