# How do I achieve a lunging motion without pneumatics?



## DreadKnightswife (Oct 16, 2011)

The Dreadknight and myself are wanting to build a prop that essentially has a large mouth with lots of teeth running vertically down the torso. We would like the mouth to open and another set of teeth to pop put at the unsuspecting TOT. We havent experimented much with moving props and have considered wiper motors but think that the RPMs would be too high even on a low setting and we do not have the money to out lay for pnumatics at this time. Is it possible to even achieve this motion without pneumatics and if so what type of motor would our fellow haunters reccomend we buy?


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## corey872 (Jan 10, 2010)

Well, a jack-in-the-box lunges without pneumatics, so I'd have to go with 'yes' on the original question. Beyond that, I assume you want the prop to operate 'automatically' without someone having to stuff the little mouth back in the big mouth. So I suspect you would have to set the little mouth up on a spring, then make a way for the motor to retract it and compress the spring, then a mechanism to let the spring 'pop' once again.

This post http://www.hauntforum.com/showpost.php?p=711661&postcount=4 and associated link show a novel use of servos to create a 'wind up and sudden release' mechanism. Perhaps you could make something like that to reel in the spring, then suddenly let it 'pop' out again.


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## Rage (Oct 23, 2012)

You could use a treadmill motor from a junkyard with a pulse width modulated signal. The mechanics would be simple based on a flywheel design depending on the length of stroke you want the inner teeth to extend. Connect the whole thing to a PIR and it activates whenever a TOT gets within a certain distance from it.


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## GhoulishCop (Sep 25, 2009)

Rage,

_"You could use a treadmill motor from a junkyard with a pulse width modulated signal. The mechanics would be simple based on a flywheel design depending on the length of stroke you want the inner teeth to extend."_

That all sounds so cool...but am I the only one that has no idea what you just said? 

What exactly is a pulse width modulated signal that would work so well with a flywheel design?

Rich


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## Fiend4Halloween (Aug 28, 2008)

LMAO @Ghoulish!! It's simple, first insert the flux capacitor to the dilethium crystal mass, then torque down the thingamajig to the dinglehopper and wire the snarfblaster so that the red wire is postive and the blue goes up to the hemistaff. There ya have it!! =p


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## Rage (Oct 23, 2012)

Sorry.........ok you know how a treadmill starts off slow and then builds in speed as you turn the lever up?.......you can do the same thing with a Pulse Width Modulator http://www.instructables.com/id/Use-a-Treadmill-DC-Drive-Motor-and-PWM-Speed-Contr/ as an example. Actually the flywheel isn't necessary but might save on wear and tear of the motor........but if you connect the output shaft to the actuators of the "mouth". Hmmmm maybe it's better to show you. I whipped up a quick maya model to give you an idea, the pwm controller controls the speed at which it opens and closes........forget the flywheel.







and


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## GhoulishCop (Sep 25, 2009)

Rage, 

Thanks! The images really do help! But which part is the dilethium crystal mass that we insert the flux capacitor into? 

You realize now I'm going to have to try and salvage treadmills from curbs and off Freecycle? I'm finding Instructables more and more useful everyday. Thanks again.

Rich


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## Rage (Oct 23, 2012)

no problem......the mechanics I can usually figure out it's the electronics that gets me......then I have to bow to the mad geniuses on here (pshort and Otaku to name but a couple)


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## Diaval (Nov 9, 2007)

Fiend4Halloween said:


> LMAO @Ghoulish!! It's simple, first insert the flux capacitor to the dilethium crystal mass, then torque down the thingamajig to the dinglehopper and wire the snarfblaster so that the red wire is postive and the blue goes up to the hemistaff. There ya have it!! =p


No No No, that isn't right. It isn't a snarfblaster, but a snarfBLAT. Close but no cigar. Then are you sure that the dilethium crystal mass is large enough to generated the 1.21 giggawatts necessary to charge the flux capacitor? Also be sure the hemistaff has the proper rating otherwise you will turn your dinglehopper into a charcoal briquette.

Hope that helps!

Diaval


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