[MattMacLean]

EDIT: "Hmm maybe I should mention that I'm 18 and have no experience with motors, thus the reason I was asking for help. Any other suggestions? Maybe something that can utilize the the full rotation of the wiper motor?"


I am about to acquire a windshield wiper motor and I had an idea in mind. I already have a coffin built and I wanted to be able to use the motor to make a creature pop up from a lying down position. The only problem is I have NO clue what so ever on how to accomplish this. I have a couple triggers but I need help with the actual construction of this mechanical prop. So if any of you have ever done anything like this your help will be appreciated!

Also, if you have any other ideas, instead of mine, for things that I may be able to do with the motor feel free to suggest.

Thanks,
MattMacLean

 

[eanderso13]

The problem with the wiper motor is that once started, they generally will always complete a single rotation (at least the ones I've worked with). So the prop would pop up and then immediately down again.

 

[harmonicaman]

Matt --

First step; get some paper and turn your concepts into rough drawings -- this can help you sort out your thoughts and develop a parts list. Always seek ways to simplify the design. Sometimes you just have to use what's available to solve the problem. Note that everybody learns something from failure; keep notes as to what works and what doesn't so next year's display will be even better! Best wishes!

 

[Otaku]

The problem with the wiper motor is that once started, they generally will always complete a single rotation (at least the ones I've worked with). So the prop would pop up and then immediately down again.

That's a problem, alright. I got around it by designing a circuit that allows two 180° rotations with a pause in between. The board is available from Jeff at Simple Circuit Boards. It uses a snap switch to index the motor in the two positions (prop up, prop down in your case). I used the circuit to open and close a coffin lid, and it should work for your application as long as the prop isn't too heavy. Here's a video of the system in action:

 

[The Pod]

You may want to start here. You'll have to able to start and stop the wiper motor at 180 degree rotations, otherwise like eanderso13 said, he'll just situp and back down.......

 

[MattMacLean]

Hmm maybe I should mention that I'm 18 and have no experience with motors, thus the reason I was asking for help. Any other suggestions? Maybe something that can utilize the the full rotation of the wiper motor?

 

[Otaku]

No problem. Hmmm...perhaps a roller cam device? Here's a link to some mechanisms that show how a cam could work for raising and lowering a prop. This kinda requires that you use a motor that has the parking feature (single rotation then stop). Take a look:

Cams and cam followers

A cam could be used to quickly raise, hold for a moment, then lower the prop. Use a small fixed wheel mounted on the back of the prop to engage the cam on the motor shaft. Again, this depends on the weight of the prop. I'd recommend using a 5VDC power supply to run the motor - this will give you a slower rotation and a longer hold time.

 

[MattMacLean]

You seem to be very knowledgeable in this topic and I appreciate your help greatly. How long do you figure it would take to raise the prop because I'm relying on it for a quick scare. If that isn't possible do you have any other suggestions for what I could make with the motor? It doesn't necessarily have to be a scare prop but could just be something cool looking to add to the atmosphere.

 

[Otaku]

At 5VDC the motor will run ~15RPM, about 4 secs per revolution. That will raise the prop pretty quickly. Another suggestion for a good scare prop is this grave jumper. It's running at 12VDC so it's pretty active - at 5VDC it would have a slower, creepier motion and wouldn't jump around too much.

Denhaunt's Grave Jumper - HauntForum.com