PSN-L Email List Message

Subject: Re: Acouple web images and text of the ball bearings rims support
From: John Popelish jpopelish@........
Date: Sun, 06 Nov 2005 15:11:23 -0500

ChrisAtUpw@....... wrote:
> In a message dated 06/11/05, jpopelish@........ writes:
>>The upper bearing is made with the other half of the outer race 
>>epoxied to a small slice of aluminum U channel so that it completes a 
>>loop.  The part that holds the ball is slotted with the dimple in the 
>>inside of the slot, so it can pull on the ball.  The channel slice has 
>>a hole for a mounting bolt, opposite the half of the bearing race. 
>>The groove is horizontal.
>        With one groove horizontal and the other vertical, the ball bearings 
> will be seeing surfaces with dramatically different rates of curvature. This is 
> very likely to effect the balance setting, the freedom to swing and the 
> period.

Yes, I agree.  Both groves should be horizontal so the balls roll 
along the grove, instead of scuffing across it.


>>This hinge makes use of the exquisitely precise, smooth and hard 
>>surfaces intended to carry load in the original bearing.  I hope to 
>>get around to testing the design soon, but life keeps getting in the way.
>        I doubt if it will give you the results that you want, for the reasons 
> that I have stated, but do try it out and let us know the results! Have a 'do 
> it now campaign'? 

Easier said than done, but I will let you know the result of this 
experiment as soon as it happens.

>     You might just 'get away with it' if you used a very much smaller 
> diameter balls in the ground outer bearing track and aligned both tracks horizontally?

The balls are about 1/16th inch diameter, now.

>       If these are ordinary bearings and not stainless steel, you will need 
> to put a drop of light oil on the contact point (clock oil?) and make an 
> overlapped paper screen around the joint to prevent the oil from collecting dust.

The balls roll such a small part of a degree for the full +- 1/4 inch 
of boom end movement that I will probably just sit them in a blob of 
grease.  This will keep dust out of the contact points.  It will 
absorb a little energy as the boom swings, but a lot less than I will 
have to absorb, elsewhere, to achieve the desired damping.


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