Ball and Socket Joint Question

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  #1  
Old 02-10-05, 02:30 AM
shortygb
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Ball and Socket Joint Question

I am planning to join a pole on to a ball and socket joint and mount the socket onto a base. i want to mount 2 springs on to the left and right sides of the pole and attach the other side of the spring to the base. i need the joint to move in all directions and when it moves left to right (where the spring are) it springs back in place. but when it goes up and down it stays in that position without springing back to its origonal centred position. e.g in the "above view" when it is in position A (B,C etc) it stays in that position without moving back to position G (centred). Is this possible to do? or are there any alternatives?

BALL JOINT
. . . . . |..|
. . . . . |..|<-----pole
. . . . ..|..|
. . . . /.|..|\
. . .. /. |_| .\<------Springs
. . . /. /// \\ .\
. .. /..|||||| . .\
__/___\___/____\_
............^<--------------Ball and socket joint

(Please ignore the "." it was the only way i could make the diagram)

ABOVE VIEW

A___B___C

<---G--->

D___E___F



I hope the diagrams help
Thanks
shortygb
 
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  #2  
Old 02-10-05, 03:33 PM
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I'm not sure I follow. Let's use compass points: do you want it to return from East or West, but stay put at North or even North-East? Does "stay in position" mean some kind of weight-supporting friction joint, or just the absence of spring?

Roughly what scale is this?
 
  #3  
Old 02-10-05, 05:59 PM
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Consider a typical lavatory faucet single lever ball type valve as a basis for an initial outline.

The ball is hollowed; then halved. (The amount of hollowing varies based on the ultimate design).

The pole becomes one arm of a two directional lever. The arm is fixed at an enlarged pivot point. Another lever arm subtends from the enlarged pivot point in the opposite direction.

The pivot point rotates about a rod or shaft that is fixed between the ball halves.

Side-to-side movement of the upper lever arm is accommodated with a slot in the halves. A spring return mechanician is accomplished with either a single spring that is slipped over (and/or affixed to) the lower lever arm and another mount point that has been cast, molded, or machined, into the ball halves, or flats (and/or mount points) are cast, molded, or machined into the bottom on either side of the enlarged pivot point and two springs are used with corresponding internal mount points.

You asked if it was even possible! My clever lever says "yes". When it doesn't exist..., make it happen! Or step aside.

How well, if at all, this outline suits your purpose is suspect due to the number of variables involved.
 
  #4  
Old 02-10-05, 08:27 PM
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Couldn't have said it any better than 2000 did!

What will this thing do?
 
  #5  
Old 02-10-05, 08:58 PM
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Hi shortygb,
- I believe the springs would exert tension to pull it back wherever it went in this configuration. ie. -if it bent to A, then spring CF mainly and spring AD secondly, would drag it back to centre. If you want it to stay down on lines ABC and DEF then how about putting a piece of steel along those lines and a magnet on the pole?

Do it Right - Do it once.
 
  #6  
Old 02-10-05, 10:00 PM
shortygb
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I will be using the mechanisim for something like this

http://www.volny.cz/michaljanak/hshift/myhshifter.html

exept the pole will be attached to springs on the base by a ball and socket joint.

i want the pole to move east-west and when it is in north south or noth west, south east etc positions it stays in the place with out returning to its origonal place.
 
  #7  
Old 02-11-05, 03:41 AM
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So this shifter-thing will travel on three paths; NW to SW, NE to SE, and - with return to center - N to S?

The magnet idea sounds better than the usual, which is to put friction on the ball by tightening a split socket. You could even have more attractive stops at the corners or anyplace between, that way. The pole could be magnetic or the guides could be, or both if you want to incorperate repulsion for a nifty ergonomic.

I'm thinking push springs not pull could handle the center return from N and S, and wouldn't interfere with the other movements. A spring would push a bar, which would push the pole. The bar could be "H" shaped to catch the pole, or "U" shaped so the pole can slip past if heading NW from center, for example. It is also possible to use a "V" or semicircle shaped bar that folds down (also with push spring) so the pole can travel direct from NW, through the reluctant N area, to NE.

In all these, you can hide the mechanism by sending the pole through the ball, and doing everything on the reverse end.
 
  #8  
Old 02-11-05, 04:45 AM
shortygb
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the shifter needs to be centred in a central positon (C) and will be able to move to positions NW, N, NE, SW, S and SE. the pole needs to stay in these positions until it is moved out. the spring would idealy need to spring back to the centre position when in the W to E "lane". i want to setup the springs so the pole attached to the joint will spring east and west without springing when in the NW, N, NE, SW, S and SE positions.

NW . N . NE

W---C----E <---------spring back when in W and E positions no in the others

SW . S . SE

hope this clears thing up
 
  #9  
Old 02-11-05, 12:19 PM
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Then the push springs would be at W and E, not N and S.

The reason for sprung guides - instead of springs directly tugging the pole - is that they only act on the pole when it interferes with them (in the W and E areas, where their shape describes the keep-out).

You can visualise the function as a square boundary that's been pushed into an hourglass shape; the constricted (W and E) sides being flexible.

A sprung guide can be made all sorts of ways. It could simply be a spring bent into a "C" shape, or a loop of spring steel. It could be a shaped bar or plate backed by any combination of springs. It could also pivot down, not slide back; it will return the pole to centre when the guide returns to near horizontal. I like this last option because the guide can easily work off any kind of spring, and by tweaking its pivot point and where the spring is anchored it can be made to almost latch (scant resistance) when the pole reaches a limit, so you could use four of these: two hard (W,E) and two soft (NW through NE, SW through SE), and the pole would always center when not along the N or S extremities.

Sprung guides are a direct way to map the exact ergonomic you want. I'm assuming this is will be some kind of hand-operated shifter.
 
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