How Can I Get This Pivot Point To Stay In One Point?

[itsdonny]

I'm trying to figure out a solution to this design. I want to add a spring to this joint so it can flex up and down and I want the neutral position to be at 45 degrees as pictured. So if you push it either way it springs back to this position. At the same time I dont' want the arm to bounce around so I want to make this 45 degree position sticky. Perhaps a detent could hold it in place until pushed beyond a certain tension.

So I'm looking for ideas as to how I can 1. add spring tension to the joint and 2. have a sticky point. Any ideas would be appreciated. Feel free to modify the drawing I made if you're feeling motivated. Or if you can think of some examples where something like this has been done, please let me know.

Thanks!

 

[itsdonny]

Oops, here's the image:
http://www.notesofrock.com/temp-images/hinge-ideas-02.jpg

 

[pantaz]

I can think of a few methods, but you've left a lot to the imagination. What are the dimensions, materials, forces, ...?

 

[itsdonny]

Good point. : )
The body will by made of some type of plastic and will be about 6" long. The arm is made of fiberglass tube with an O.D. of about 5mm, and the length of the arm is about 16" with about 1 oz of weight on the end. The spring will of course need to be strong enough to elevate that throughout its range of motion. Thank you.

 

[pantaz]

There are several ways to go -- a lot will depend on your budget. You also failed to mention if this is just something you're building for yourself or if it's destined for production.

The spring-return feature can be done with a simple clock-spring or torsion-spring. A ball plunger for the centering detent can also offer some damping function.

Damping can also be accomplished with commercially available rotary dampers, such as these:

http://www.mcmaster.com/#rotary-dampers/=lc3yys
http://www.reidsupply.com/products/...gs-shock-absorber-accessories/rotary-dampers/​