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That is funny this thread popped up yesterday, I was just thinking about wanting to make this prop too. I'm still trying to wrap my mind on how to rig up the wires to get the correct pull for the mechanism to properly work. I also think getting a great prop head with realistic latex eyes is crucial for making this prop going from good to great.
 

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That is funny this thread popped up yesterday, I was just thinking about wanting to make this prop too. I'm still trying to wrap my mind on how to rig up the wires to get the correct pull for the mechanism to properly work. I also think getting a great prop head with realistic latex eyes is crucial for making this prop going from good to great.
Purely speculation but I don't think there's any wires involved. Definitely an aluminum scissor mech with either solid linkage or springs to each side of the box. If you watch the video closely, just a slight inward movement of the box halves retracts the head pretty quickly.
 

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Discussion Starter #5
Yes Wickedbeernut they have some awesome props!! mostly out of my price range tho!!
J-Man and MichaelmyersSickHead, I cant really tell if there are wires or hard linkages controlling this thing, in one part of the video it looks like cables mounted to both sides of the box on the bottom. in the video of the little dinosaur I don't see them, just what looks like a spring on the left side?? I can think of a way to make it work using both!! I am going to try to make a PVC pipe mock up this week to test my ideas before making anything out of aluminum!! I also noticed that the sides of the box open and the back stays flat against the actors chest, this gives a nice platform to mount the mech. too. Anyway I will let yall know if I come up with anything!!

Thanks,

HH
 

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I would love to see what you come up with...so you are going the scissor mechanism route? I was wondering where to even purchase these, the only thing I coiuld think of was maybe buy two of these and link them together to get near the 4' length this prop achieves.

http://www.ikea.com/us/en/catalog/products/70154800/
The bars all screw off so you would already have threaded rod to attached prop items or to a base. One thing I noticed on the science of this is you would need a slot at the base because as the scissors extend the base ends move towards each other. I definitely want to make one of these but I'm in the middle of another build right now and its way too easy for me to get distracted haha
 

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HH,
Again, purely speculation but I would think the cables attached to the bottom of each side would be to limit how far the box is pulled open.
MMSH,
The Ikea scissors are probably way too stiff for this, the pivot point has to be nice and free. Scissors are easy fab with flat stock aluminum using hardware with nylock nuts.
 

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HH,

Yes Wickedbeernut they have some awesome props!! mostly out of my price range tho!!
I'm definitely not suggesting you buy one. I'm suggesting you study all of the VFX videos in building your own.

The link I included (above) would seem to reflect a prototype. The scissor linkage seems to have changed slightly with the production version,


A scissor (or accordion) linkage typically has a sliding joint at the base. With the prototype, the upper joint at the base (back of the box) would appear to simply "float". With the production version, the upper joint at the base would appear to be fixed.

wbn
 

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Team,

I get the sense the VFX design is continuing to evolve (nothing wrong with that). Here's a video from last weekend's TransWorld in St. Louis,


The VFX footage starts at 4:48.

They seem to have simplified the cabling system,


The cables now appear to be symmetric. I don't see what appeared to be a spring in the earlier videos.

It looks to me like they've added a sliding joint at the base,


Note: The top of the base doesn't move as it did in the earlier videos.

Here's a video of a "dual" scissor / accordion linkage I built out of aluminum 15+ years ago,


I apologize for the poor video quality. Here's the corresponding design drawing,


My linkage has a sliding joint on both ends. A lunging puppet only needs a single sliding joint.

My linkage is actuated using a pneumatic cylinder. This would be replaced with the cables.

A lunging puppet wouldn't warrant a dual scissor linkage.

I incorporated a modified version of my linkage into my earlier drawings,


wbn
 

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Interesting VFX video...the prop seems to retract when he held the box more upright without closing the box at all.
Yeah, I suspect this version does not have any spring for retracting. It appears that you just tip the prop upward slightly while closing the box. If you hold the box halves fully open, it won't retract even if it's tipped up.
 

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Discussion Starter #14
Thanks Wickedbeernut, lots of good info there!! I made a quick mock up this week with the scissor mech. laying horizontal and the ends connected to the sides of the box. It works but not very well. you have to open both side of the box just right or it veers off to one side or the other. I like the vertical design much better. I was trying to go for something simple to build!! This weekend I will redo it with the cable design and give that a shot.
J-Man, I think I like the idea of having the return spring in it. Seems like it has better action!! If I can I will snap a few pics!!
 

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Discussion Starter #15
Hello, I finally got a chance to rework my prototype this past weekend. The new mech. seems to work pretty good. Keep in mind that I put this together quickly and nothing about it is precision!! It binds a little because the holes in the PVC pipe are not accurate. It does prove that this design will work. I am rebuilding it using 3/4" square tube and nylon bushings using a jig to drill the holes. The return spring will be 2 springs, one on each side eliminating some of the spring sound heard in the video. Below are a few pictures and a quick video showing the action!! Don't laugh too hard because like I said this is just a quicky prototype!! Any suggestions or comments will be great!! Thanks HH
 

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Discussion Starter #18
Thanks WBN!! I believe it will all work better when I rebuild it with bushings and different springs. And of course a real box!! The piano hinges are a great idea, I think that's what I will use. I still need to test how fast the head comes out, since there is no front on my test box I am concerned that the head may hit the box before it is open enough to clear it!! if it does I think I can put some slack in the cables and hold it back with some small springs giving the box time to open a little before engaging the scissor mech.!!
 

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Discussion Starter #20
I have tried putting the cables in several spots and this seemed to work the best but I wasn't thinking about the head hitting the front of the box!! I will put a temporary front on the box and see if it hits. if it does I will play with the positioning of the cables some more.
 
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