Thread: scissor lift prop using wiper motor - would this work?

Tweet

I mocked up an animation for what amounts to a trash can trauma.

Since I won't be able to get my hands on an adequate air supply before Halloween I want to try this with a wiper motor.

Check out this video and let me know if you think this would work.

On 'paper' it seems like it would as long as I made sure to build a very smooth mechanism.
I figured that I'd need about a 4.5 inch throw to move the prop about 3 feet... actually i didnt figure anything.. I just animated a scissor lift, then added the measurement scale.. then added the wiper motor and linkage.. it was all pretty much luck of the draw. haha.

the only thing i DID try to figure out and show to scale was time to full extension. on a 41 rpm motor it takes about .38 seconds to turn 1/2 rotation. Figuring there's no way that thing is going to extend that fast I'm guessing with weight added i'd be looking at 1-2 second for full extension.

I plan on putting a chicken wire torso with a hollow head (grandpa) on the top of this thing as the guy in the ticket booth at the carnival.



Here's the video... feel free to poke holes in any of this.

This would work for a prop that just goes continuously up and down. If you're looking at having it stop in the contracted and extended positions it's going to be difficult to do with a wiper motor. A linear actuator would be too slow I would think for this prop. However linear actuators are just motors that turn in forward and reverse depending on polarity of power. At each end of the travel there is a micro switch that turns power off. I would think you might be able to use that concept to get it to work, but I wouldn't be the one to ask how to wire it all.

BTW, I love the prop! Did you make him?

Yeah. I made that prop.
Here's the original thread.
cemetary groundskeeper rocking chair guy

I tried a couple of 'new to me' approaches using caulk for sculpting parts of the head and using a old brown tshirt smeared with caulk for the neck skin which worked out pretty good.

As for using a wiper motor on this. I I was hoping to us a some sort of limit switch and timer setup to trigger the prop or a microcontroller if i can get those things figured out soon.
the only issue I see it spin down time on the motor. depending on how i control it I can offset the position of the limit switches to get it to stop at each end where I want it.

depending on the load, it might halp bring the motor to a stop fairly quickly.

I just looked into turning a wiper motor into a servo which seems more complicated than I think I need.

There must be a way to stop the motor at a 'home' position since on your car, the wipers stop at a specific position to park the wiper blades. Looking into that now.

Would this work? For demo purposes the motor is cycling 3-4 times, but the circuit can be adjusted to allow only two 180° rotations.

http://s73.photobucket.com/albums/i2...rmotordemo.mp4

You could use a picovolt to control the movement of the WWM. Picovolt can be adjusted to rotate, stop, reverse, change speed etc.

otaku,
that would be exactly what I need sir. do tell do tell.

I found this reference and it made me think about opening up the motor and creating a 2nd park position internally 180 degrees from the normal one.
http://www.stensat.org/projects/wipe..._internals.htm

not sure how you're doing what you're doing in that movie but assuming the time could be adjusted between 180s and the initial power on could be triggered by a cheap motion detector i think we have a winner.

here's my pseudo code for this...
1 motion detector awaits trigger
2 wiper motor rotates 180 degrees from home position and stops at out position
3 *adjustable pause*
4 wiper motor rotates 180 degrees to home position
5 goto 1


that something which can be done with your motor hack? please say yes and send me the info! haha.

@ DoctorGrim: At $50 + shipping I'd like to see if I can do this cheaper. Less $$ on props means more $$ on candy!!! aka.. i'm cheap.. or broke. these days it means the same thing I think . haha.

>f I can do this cheaper. Less $$ on props means more $$ on candy!!! aka.. i'm cheap.. or broke. these days it means the same thing I think . haha.

I agree completely. From past experience, I'm not sure how much cheaper the circuit board, relays and difficulty (at least it was difficult for me) is comparatively.

the one thing i RARELY, if ever, take into consideration with this stuff is my time. normally I can charge 40-50 an hour for graphic design services when the opportunity presents itself but I seem to have no problem spending 6 hours building something myself I can just pay $50 for.

i think it's just parting with the physical money vs parting with a fraction of it that gives the illusion of savings.

thanks grim.. now i'm looking into that controller again just in case otaku's solution makes me nervous. lol.

keithcorcoran, otaku is using the same circuit to run both of these prop so it can do what you want.

yeah. i stalked his video album after he posted that video. it's perfect...
just waiting on the info and i'm making that sucker most riki-tik.