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wiper motor motions


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So my most recent obsession is with animating some figures for displays. I plan on using things like wiper motors and those little motors that they use for the deer that go in your yard.

My question is, is there a site (or sites) that kind of show or explain how to get desired effects out of the motors?

For instance, one of the first things I have planned will require an up/down motion. So I know I need to have the motor turning a wheel in the vertical plane. I also know that the distance from the center of the wheel to my pivot point is 1/2 the distance my up/down motion will travel. What I don't know how to do, is make it look like when my item goes all the way up/down, that it pauses. I have to imagine by hinging one or more sections in the arms that come off of the wheel, I can allow the wheel to keep turning (which is preferred) yet give the appearance that the item paused at the apexes.

I am not naturally mechanically minded, so I have been running through designs through my head, but I figured someone out on PC probably has an explanation or some videos somewhere.

Thanks,

~Jason

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This isn't a "how to" video... but is shows the back of one of my animated characters. The motor attached to this character was a reindeer motor which has now been upgraded to a windshield wiper motor... but the mechanics are the same. I don't know about getting something to appear to stop at the apex... but this might give you an idea on how to go about creating motion using a motor.

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You might want to PM DanoNJ. He has made countless items using wiper motors (I keep my hood locked at night because of him). The only help I can give is that he uses 5 volts to "slow" the RPMs down a bit...

Here are some threads you may want to look at:

http://forums.planetchristmas.com/showthread.php/41177-Decorating-elv

http://forums.planetchristmas.com/showthread.php/41179-Waving-snowman-with-bunny

http://forums.planetchristmas.com/showthread.php/40392-Surfing-Santa

http://forums.planetchristmas.com/showthread.php/31771-Jack-in-the-Box

http://forums.planetchristmas.com/showthread.php/33060-Dancing-Reindeer

http://forums.planetchristmas.com/showthread.php/30378-Toy-shop-project

There's more - I just do not feel like searching anymore...

Edited by B_Regal78
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Thanks for your video jr. What are you using for he strapping and pivot points?

I forgot about dano, he does some great work, I will have to pick his brain some.

I have given up on the pause for now and will focus on just making it run smoothly and consistently. Looks like I have a lot of videos to review for tips/tricks!

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Animation is a lot more heavily used on the Halloween side than the Christmas side. A lot of these use wiper motors (flying crank ghost, axworthy ghost, etc). So you might want to look there as well for inspiration/education/etc. There are literally hundreds of halloween sites with how-to's that you might be able to adapt. For some reason, Halloween sites also outnumber Christmas web sites by a huge margin (not complaining, just surprised).

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If you use 12 volt car wiper motors, then use a 5 volt power supply (normally computer related) then you will get the stops that you are looking for. The nice thing about wiper motors is that the "Throw" is already built in, When using say a BBQ motor then you must build the throw into the mechanisms

Tony

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Hmmm, that is interesting. I was trying to look up more on the brakes you were talking about, but it is still a little confusing. I started with this website: http://www.stensat.org/projects/wiper_motor/low_res/wiper_motor_internals.htm

And from it it seems like I could rig up the wiper (assuming the Monster Guts wiper motors have the parking brake lines) to start, and then stop after one revolution (is that what you were thinking?), then wash-rinse-repeat. The problem I see with that is that the brakes are probably at full revolutions, so the motor would probably stop at one end of my vertical path only, that sound right? Is there a way around this?

~Jason

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Jason, if you want vertical motion and a pause without stopping the motor you just need a bit of over travel. Basically you're pushing with a spring. You'll need two for both ends of travel in your case. When you hit the end, the rest of the travel is taken up by compressing the spring. Find a bi-fold door and look at the spring mechanism at the top of both doors to see what I'm talking about.

If you still don't understand, let me know and try to mach up something.

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Pretty neat Ernie. I hear what you are saying, but let me say it on here to make sure I really do following. The top and the bottom of my vertical rod (or whatever it is that is doing the up/down motion) will have a spring attached to it. The spring will be naturally expanded not sure how to word it). I would then do something like travel and extra 2 inches in both vertical directions but the spring will eat up the last two inches by compressing against something. That sound about right?

I guess the only hitch would be that whatever the spring is pushing up needs to be light enough so as to not compress the spring due to normal gravity, right?

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Yeah you got it right. The spring just has to be strong enough to lift the weight.

Now that I re-think this, you only need the upper spring. The rod just needs to be longer to travel down below the lowest resting point of the object you're moving. The object should hit a resting point and stop at the bottom.

So the spring is doing the lifting and can over travel and gravity brings it back down to a fixed point even though the rod will continue to travel a little farther.

The spring and rod is nothing more than the spring and ink cartage in a pen. It's also got the over travel that I'm talking about.

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It sounds like Ernie has good suggestions which will enhance what will naturally take place. When converting the circular motion to linear motion as you described, the "ends" will naturally be slower - might appear to be a pause depending on what you really mean and on the slop in the linkages. Typically the center of the stroke moves faster than the two extremes since the linkage would likely be pushing the mechanism parallel to the direction of motion while at the apex (and trough) the linkages would have the motion generally running perpendicular to the linear direction. Hence a natural pause. If you think of it as a pin on a wheel, as the wheel turns part of the time the pin travels more parallel to the direction of linear motion and part of the time perpendicular, hence the varying speeds. This is how my skeleton ghost works as he turns his ship wheel - he seems to pause at each end but I did nothing special to engineer that (in this case it is nice because it seems to mimick how one would naturally steer a ship (assuming constant overcorrecting of steering :-) ).

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Yeah, Ernie is onto something here. The pen analogy makes it pretty clear (which is what I need).

I also talked to DanoNJ on the side and pointed me to the cam idea. I hadn't read up on cams before, they sounds pretty interesting and actually seem like they could do something similar. I need to mock some stuff up and see how it shakes out (who knows when I will find some time for that!.....).

~Jason

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