Modifying the classic Push Puppet? 1

[td24]

Saw this video about how to build a Push Puppet (Link)

Is there a way to duplicate this mechanism using a stronger material other than string?

 

[tbuelna]

Try this "string".

200lb tensile strength and it costs about $0.20/ft.

 

[MikeHalloran]

I'd try the braided line used for fly fishing.

Monofilament is strong, but it's hard to tie it into a knot that won't loosen immediately.

Aramid is worse than monofilament; it splinters (watch your eyes!) when bent to a tight radius, like in a knot, and the metal crimp rings sold for terminating it won't hold, even when used with the recommended special crimping tool.

I'm guessing that you might be able to terminate aramid into a reverse tapered fitting filled with epoxy, sort of like you terminate wire rope with molten zinc. You will probably need more patience than I can muster.







Mike Halloran
Pembroke Pines, FL, USA

 

[tbuelna]

Some form of braided material would definitely have the advantage of greater flexibility. A piece of 100lb mono-filament is pretty stiff.

It would help to have more details about the application. Some type of heavy polyester or nylon thread might be satisfactory, versus a piece of common cotton string.

 

[td24]

I'm looking to apply this same type of mechanism within a different apparatus, but using string or fishing line to re-create the mechanism isn't a viable option

Is there a way to re-create this type of collapsing mechanism using plastic?

The reason I want to duplicate the Push Puppet mechanism is because it's more applicable to the apparatus i'm working on than the typical lock/release spring loaded mechanism because of physical obstructions that are present with the apparatus

 

[tbuelna]

The mechanism relies on tension in the string to compress the elements such that their end joint faces all become axially constrained, and them they become un-constrained and separate when the tension on the string is relieved. In order to help, you need to provide more details of your particular application. With any kinematic joint there are a potential 6 degrees of freedom, 3 translational and 3 rotational. In order to fully constrain a joint as shown in your skeleton puppet, the joint face would need to provide 3 rotational constraints and 2-1/2 translational constraints. The string will only provide a translational constraint in the direction it is loaded in tension.

While it might be possible to use a plastic tension element for your mechanism, you need to provide more specific details before I can say for sure what might work.

 

[3DDave]

It's hard to imagine a case where rigid tension elements could work that flexible tension elements cannot.

You'll need to explain more clearly why fishing line or string are unsuitable. What failure mode to they have that you want to avoid?

 

[tbuelna]

I can see a situation where an arrangement of rigid links (like a chain) that have swivel joints at each end that align with the skeleton joint centers when tensioned could possibly be made to work.

A braided yarn or thread works for this application because it is very flexible when unloaded. But something like 100lb test mono-filament fishing line might be too stiff to permit the flexing of the joints desired when unloaded.

 

[td24]

The use of string/fishing line isn't practical because the goal of this apparatus is to go into mass production and production would be slowed with the threading of strings through holes, when compared to the speed of production that is desired.

Anyway, the reason a typical spring-loaded lock and release button will not work is because the objects that need to be collapsed will be rotating horizontally 360 degrees around a vertical tubing unit. There can be no obstruction within the vertical tubing unit and positioning a collapsing mechanism on the outside of the vertical tube will obstruct with the rotating units. Also the collapsing mechanism has to take in account that the location of the horizontal rotating units will vary, so the collapsing mechanism must be available around the entire vertical tube.

With that in mind, the only option I see is creating a separate tubing container for the collapsing mechanism that is positioned in between the vertical tubing and the rotating horizontal units

What do you guys think?

Thanks to anyone that has contributed so far, your input is appreciated

 

[MikeHalloran]

>>>looking to apply this same type of mechanism within a different apparatus<<<

... is a proven recipe for failure.

... especially, given that you can't reveal the nature and specifics of the 'different apparatus'. We can't help you build a better automobile if all you can talk about is a boat.


Instead, you have to evaluate the needs of the 'different apparatus' in its own context, and solve the problems you can foresee within that context.


Mike Halloran
Pembroke Pines, FL, USA

 

[3DDave]

I think it's time for a picture.

 

[Tmoose]

http://i21.geccdn.net/site/images/n-picgroup/FOW_52-585-500.jpg

 

[3DDave]

Tmoose - nice picture, but that's not what the OP is describing.

 

[Tmoose]

Hi 3DDave

The OP did not say "no" When TBuelna said "I can see a situation where an arrangement of rigid links (like a chain) that have swivel joints at each end that align with the skeleton joint centers when tensioned could possibly be made to work. " .

The style of indicator mount in the picture I provided would function as I understood imagined it described, right up until OP most recently said " the only option I see is creating a separate tubing container for the collapsing mechanism that is positioned in between the vertical tubing and the rotating horizontal units." That left me with an empty thought balloon.

Without the picture you asked for my balloon will likely remain empty.
Since TD24 has not logged on for a couple of days, and all his log-ons were over the past weekend, perhaps he has moved on.

regards,

Dan T