Rotational plastic bearing (or something alike)

Hi folks,
I need some ideas and/or pointers.
What I'm trying to do is to rotate a plastic case of 80x60x60 mm (80mm wide)
about the Z axis. The simplest solution would be to glue it to the output shaft of a standard servo. The problem is that this piece will be installed on my Koli robot, that is supposed to see some offroad action. I'm afraid that if I secure the case (it will hold a webcam and two sonars) from the bottom only, it will be too succeptible to vibration and may even break apart. My next idea was to secure it on the top too, to a fixed plastic piece that mounts directly to the robot base. But now I'm struggling to find which is the best way to attach it.
I was thinking about some kind of needle bearing that has rotational movement, but it needs to be small and very lightweight. The total weight of this casing and equipments that will go inside won't exceed a few ounces. I'm trying to design the concept and I'll post in here later for opinions.
Thanks
Padu
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Read this:
http://www.ifirobotics.com/docs/EDU_Mechanical_Guide.pdf
                John Nagle
Padu wrote:

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At a few ounces and 8cm max I don't think you really need any bearings. What kind of servo is it? Or by Z-axis do you mean the output axis is parallel to the ground?
I do think the glue might not hold, and so the case would pop off eventually. A screw into the servo horn would be preferable.
A low-tech bearing: glue a nylon washer on top of the servo, so that the case comes into contact with it. Use a fairly large inside diameter so that the amount of plastic that rubs is relatively small. This would provide good support and with the right kind of lubricant shouldn't be too frictional.
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wide)
installed
sonars)
that
of
Here it is the first attempt... honestly I didn't like. The blue walls are 3mm polycarbonate.
http://www.merlotti.com/EngHome/rover/camera%20pan%20tilt%20concept%20-%20revA.jpg
or http://tinyurl.com/9po9y
One of the dificulties is that I'm trying to position the lenter center on the intersection of the two axes. I'm aware that if I didn't have this restriction, it would open the door for other types of designs. I'm not really sure if having the lenter center turning outside a rotation axis would be too bad for my purposes.
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