Plastic Ball and Socket

What load is it going to handle?

I'd start by getting a pencil in my right hand and a tennis ball in my left.

I'd draw the latter with the former... I'd then rationalise the fingers holdong the ball down to 3 or 4 in number and taper them so that the wouldn't snap off at the root.

I'd stay a looong way away from a computer for as long as possible.

The computer can be used to draw it up and analyse it...It won't actually have the ideas.

Del

Thanks for the reply 'Del the cat'.

The load is going to be around 10 ounces. So that shouldnt be a problem.

Its a good point you mentioned with the tennis ball. At this moment in time I am visualising the ball and the socket(also a ball, cut in half for the sake of argument), with the ball fitting in the socket. If the socket was say a ball cut in half then obviously the ball would loosely fit into the socket, and keep falling out which is undesirable. Then if you imagine the socket(ball with a 1/4 off) you could not manually fit the ball into the socket.

Therefore what is the optimum cut(of the ball socket) to create a socket for a good manual push fit?

Hope this all makes sense?

If the cup is part if the base, could you not have the ball and stem inserted through the back of the cup so that when you attach the cup to the base, the ball can't come out! You could also incorporate fine adjustment on the ease of movement of the ball!

As per usual, my sizing has gone up the Swanee!

Brought to you by that famous industry standard CAD program 'Paint'. For all your designing needs!

My Super-Specs don't work, but rt click - save picture as - open (in a viewer) - zoom does work. Nice idea.

John

Thanks for that viewing tip! I didn't know that.

In fact it did not work on my Mac, but knowing the concept made me explore a bit, and ctrl-click on the image did allow a 'Save Image as..." etc.

Touch

The 'Adjusty thing' could well be a threaded stud, while the retainer would have internal threads to to match the stud. You would need some method like a locknut to prevent loosening.

For Snap-on units, look at the adjustable coolant nozzles used in machine shops.

Dick

That is the usual design for these types of joints. The opening in the socket is then generally sized to a specific range of motion; perhaps even to have more range in certain directions than others. If you need to design a "snap-in" joint, material selection and thickness will play the largest part in sizing your opening. Work with your material supplier to get your design in the ballpark and prototype to validate. You'll probably need to plan on two prototypes: one to see where your initial design falls and one to verify your "adjustment" prior to production release.

Go out to your car (or a friends) and have a look at how the interior mirror is attached to the windscreen. Go to the auto parts showroom and have a look. You'll find a design that has worked for years holding about the mass you mention in the vibrating environment of a vehicle interior.

Thanks for all your replys. Special thanks for Mr. Truman Brain for going to the trouble of drawing the diagram. Maybe I should of done that from the start so that people could understand exactly what I am trying to achieve.

At least for my prototype I can use Mr. Truman Brain technique to help me tweak things. Although ....

There is still a point that I really dont have an answer for as yet. What is the socket(or cup) cut diameter for a given ball size? Whats the optimum cut diameter that will allow me to push fit tightly these two parts?

I feel deep down there is probably answer to this. Although maybe I am asking for too much : (

JustanEngineer has the right idea t...

Go and look at STUFF !
The toy store is often a great source of inspiration. Also the humble spring type clothes peg.... this would give you two flat plates with holes in, which are spring loaded together...simple and effective...but not pretty.

I can't answer specifics about cuts and clips and such like..look at nature too.
So may idiots make 'spring fingers' and such like that just snap off at the root...nature grows things with nice tapers.

Open your eyes Grasshoper...be at one with design .

Del

Thanks for your reply 'Del the cat'. I think you and JustanEngineer are correct. Over the last month or so I have been looking looking at various similar products like the car mirror to GPS ast nav holder. All of which are essentially the same as what I want to achieve. All of which somebody must of designed in a similar nature.

I suppose my alternative to this is to pay somebody to ensure the measurements are correct!

If you are designing it to be moulded from plastic, you have plenty of flexibility (ho ho) the tool for the socket will be 'metal off' to increase the strength of the fingers and your choice of plastic* and surface finish will also effect the grip.

Design the basic shape and mechanical arrangement then slap it onto the CAD and analyse/fine tune the cross section and material choice to give the required grip/insertion force/strength.

*The difference between something like ABS and glass reinforced Nylon is huge.

Del

Check out the mounts made by Ram. I use them on my motorcycle and vehicle applications. http://www.ram-mount.com/ They function well and have versatility with the universal mounting plates.

www.mcmaster.com has plastic ball & sockets= small plastic motor couplers that can be adapted. you could also use the swivel from a table top camera tripod.

Thanks DGCYS for your reply. That helps to know there are suppliers who do this. Do you know of any bussinesses in the UK that provide such a service?

If you are working on a smaller scale (10mm ball diameter), the plastic ball studs and sockets used to mount reflectors in headlamps may be of interest. I've seen plastic screw mount, twist mount, and snap mount sockets and studs: http://www.itwdelpro.com/headlamp.html