ChatterBox Teeth - Wind-up
Description
These are a set of Windup ChatterBox Teeth, like the kind you get in gag stores or the kind "The Joker" always seems to have in "Batman". The two toned teeth are of course achieved by changing the filament at the proper time during the print. The wind-up portion is driven by a clock spring, which you can get from any old wind-up toy (or a wind-up clock, but why would you want to destroy a clock?). I got this particular clock spring from a Dollar Store Easter Toy, you can see the pictures of the Harley Riding Easter Bunny I sacrificed in the instructions.
The Drive Mechanism is a Geneva Drive, which is pretty common for a wind-up toy. You wind up the spring and it rotates a cam shaft, opening and closing the teeth. Unfortunately, we could never get the mechanism to work properly. The teeth chatter of course, but the problem here is they chatter too fast and the clock spring expends its energy WAY too fast. We still have a few days left in the competition, so if anyone thinks they have a solution for this and would like to collaborate, speak up now!
We have tried every thing we can think of and are at our wits end. We thought gears would produce enough friction to slow the clock spring down, but they don't!
Instructions
Now, the clock spring can be gotten in the toy section of your dollar store. If you want a strong clock spring, go for a toy that is heavier in weight and is meant to roll across the ground. The lighter the toy and the less it does, the weaker the spring will be, so make a GOOD selection! Be careful when you break the toy to get the clock spring out, when you break the clock-springs' case open, it tends to go flying all over the place and may cut you.
Next, you can follow the pictures on the left for assembly of the Geneva Drive. I know, the pictures are slightly different from what you printed, but it should be pretty easy to figure out. Gear Number 2 does not get assembled with the geneva drive yet. So, the only real difference is, the wheel with the axle is now a Toothed gear with an axle. Oh, and the nut that gets sunken into the wheel in the picture. That will go on gear number 2, so you can forget that step. Once you get the spring through the axle, make sure you bend it over on itself, you don't want it to come loose, because then you will have to take the whole assembly apart to fix it. Once you bolt the clock spring case together, just rotate the key to get the spring in there. DON'T FORGET to bend the other side of the spring before it slips into the spring's housing! Next you can bolt it to the bottom of the teeth. When the teeth are together, they should be able to open and close by gravity alone, if they do not... ream out the holes on the top teeth a little at the hinge. All fasteners are M3 sized. I use M3 x 12mm for the hinges and M3 x 20mm for the gears and geneva drive.
The pictures were taken from the older version, but I really wanted to get this out there and there is no time to take new ones yet.
Openscad files for the gears here: thingiverse.com/thing:8144 and the new experimental gearbox is here: thingiverse.com/thing:8148
I will upload them to this thing in a little while!
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UPDATE:
I haven't given up on this project. I have changed the entire design to be in OpenSCAD! I am also working on a parametric Geneva Drive.
The Teeth model has since changed, because I could not get this model to open in OpenSCAD. The change is for the better.... believe it or not, the new teeth loo
k SO much better!
Observe:
http://www.flickr.com/photos/5...
Those are some pics of the new teeth with comparison to the old teeth. The new teeth are great, they look even more realistic! It almost looks like you can pull each one out with a pair of pliers!
See:
UPDATE: We are going to be uploading new files soon! We have added some additional gears. Also I need to change the winder axle, I don't know what exactly happened. But the ones in the picture are so much sturdier than the recent ones I have been printing. For some reason the tabs that the winder key slide into have been breaking off rather easy. So, Either I need to print that the clock spring main axle gear thing with 100% infill or I need to do it slightly differently. It needs to be very sturdy, because ALOT of pressure gets put on the winder.
Awesome project! :)
If you can't shrink the gears, why not enlarge the teethâ½
Or apply weight to the top teeth so there is more negative torsion on the spring.
Well, the teeth already take up a good portion of the build platform already and I kind of wanted to keep them the size of human teeth. But, a huge set of teeth that chattered would be great, maybe someone should come up with a derivative.
We are currently working on a gearbox that may work. We'll see what happens, then we might have to try other things.
By the way, I am totally stealing that wound-spring power source for some future clock, if someone doesn't beat me to it... ;-)
What is the fill on the teeth? Increasing the mass of the jaws should increase the period of the chomping.
As a last resort you can probably reduce the width of the spring.
What about modifying the spring? Or how about adding something that rubs against the gear from the side to slow it down? Like a brake? Just add enough tension so that the gear still turns but not as quickly...
That's an idea, but I think I ran into a problem with this type of approach when I was experimenting with springs. You see, there is a dramatic difference between the power it takes to open and the power it takes to close the mouth. So, if we tension the gear to have enough power for one, it is not going to be the right power to do the other. I could be wrong though. Maybe I could try a few different ways to do this.
But I really think the best idea is to add more gears to regulate the speed. This is the approach most wind-up toys take and I think it is the answer. The problem for us is building a gear box the right size and shape, and we are lucky we have gotten this far with that. What we need is someone who
is up to the challenge and is really good at designing gear boxes to collaborate with us and help us win the MakerBot United Competition!
Well I'm not sure if you could make it small enough, but if you could some how make up a watch escapment gear that might slow it down. It might make it too slow perhaps if you could get it down to size.
Yes, we have thought of doing an escapement, but thanks for the suggestion. It would be just too hard to get it that small. We have watched all sorts of videos and read all sorts of stuff on clocks and watches. The pieces are just too intricate to do.
Every wind-up toy I have ever broken has worked just on gears alone (well that and a cam). So, the only route I see is to design a gearbox that will produce just the right amount of friction to slow the spring down without stopping it. We tried and tried. But this is really my first time trying to
design gear boxes and such. I mean, I understand how they work and what needs to be done, I just can't practically do it.
I could just steal a gear box from some other wind-up toy, like I did the clock spring, but I really wanted to limit the amount of non-printed parts to a few m3 bolts and nuts
and the clock spring.
The print quality of those teeth with the 2 colors is so awesome!
Thanks,
Ya, the original idea was for me to just release the teeth, by themselves. But then, I thought we could go one better and make them chatter. I was originally going to go with a servo, which would make the project so easy! But, I thought, nah, they gotta have a key and they gotta WIND UP! So I want
ed to do it classic wind-up toy style. Unfortunately, we weren't able to make them work as good as we wanted them to. And the deadline is fast approaching, so we posted them as WIP. I am hoping someone can come up with a clever idea or a REALLY GOOD gearbox that will allow us to get a little more '
time' out of the chatter.
The amount of blogging this will get tomorrow is going to break the internet.
I'm sure you have thought of this already, but why would it not be sufficient to increase the gear ratio between the turns of the spring and the turns of the geneva wheel? Wouldn't you be able to simultaneously increase the duration the spring runs (measured in chomps, as it were) and increase the torque required to move the teeth... both of which should slow the teeth down.
No?
Well, we added two gears... Big Gear on the spring, small gear attached to large wheel controlling the teeth. It had absolutely no effect on how fast the energy was released from the clock spring. It did increase the amount of times the mouth opened and closed though.
It just opened closed 21 times instead of 7 times or so.
We might be able to add more gears or make a larger ratio, but there is a limited area to work with and we can only go so small with the teeth on the gears due to the limits of printing.
Usually with these wind-up toys, the gears are very
very tiny. Here is a comparison:
Basically, I'm proposing to use a gear-box to slow things down. Sorry, that was less than clear.
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You need to add some force for the spring to work against so its energy doesn't dissipate in an instant. If you lift up one of those toys with wheels, the wheels zip around and lose all their energy in an instant. Perhaps a length of clock spring supporting the jaws open would provide enough force to keep the spring going longer.