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Author Topic: Help me fix an old key  (Read 3648 times)
VA7CPC
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Posts: 2414




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« Reply #15 on: October 22, 2011, 05:21:01 PM »

Quote
It has trunnion screws, and the head op those are  wide, drilled out,  and contain the balls 6 or so. So it will not be possible to replace a ball bearing, because it is a special part. Normally a ball bearing has an inner and an outer ring. Here is outer ring is the trunnionscrew head and there is no inner ring.

You're right -- there are no separate "ball races".  The bearing balls are loose in the trunnion screw head.   A little bit of grease will hold them in place during assembly.  The "inner ring" is a groove in the trunnion.

Nobody said it was a great design!<g>   But many, many were sold, and many are still in use.

Bicycles (from earliest days to about 1975) used loose balls in their headset bearings (the steering tube) and crankset bearings.  That give you the most balls possible, for a given outside radius.  There's no space taken up by a ball retaining cage.


          Charles

PS -- I have a Hi-Mound straight key that uses ball bearings on the trunnion.  The bearings run in a plastic outer race.  It works nicely -- no play, very low friction.
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PA0WV
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Posts: 141




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« Reply #16 on: October 23, 2011, 03:29:15 AM »

  A little bit of grease will hold them in place during assembly.  The "inner ring" is a groove in the trunnion.

Nobody said it was a great design!<g>   But many, many were sold, and many are still in use.

Bicycles (from earliest days to about 1975) used loose balls in their headset bearings (the steering tube) and crankset bearings.  That give you the most balls possible, for a given outside radius.  There's no space taken up by a ball retaining cage.


Charles, I remember as a little boy, going to take the bike of my father apart, and all the balls were jumping out, I couldn't find back all, and I didn't know the grease trick at that time... May be magnetising the balls yield a mounting method without grease required.

Yesterday there was a local hamfest, and the Surplus Radio Society, had a key collector, that dismounted the knob, turned it around and it shows "Japan", he told it was a cheap replica of the J38, fabricated in the period that Japan copied a lot of western designs.

Finally the conclusion for the topic starter may be, he doesn't need a ball bearing, but just a missing ball of the right size.
« Last Edit: October 23, 2011, 03:32:08 AM by PA0WV » Logged

Using an appliance without CW is just CB
VA7CPC
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Posts: 2414




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« Reply #17 on: October 23, 2011, 05:05:55 PM »

Quote
Finally the conclusion for the topic starter may be, he doesn't need a ball bearing, but just a missing ball of the right size.

Exactly right.
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KA5N
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Posts: 4380




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« Reply #18 on: October 23, 2011, 05:43:43 PM »

Quote
Finally the conclusion for the topic starter may be, he doesn't need a ball bearing, but just a missing ball of the right size.
Exactly right.
What?Huh??  Each ball is a ball bearing.  An assembly of ball bearings  and races are bearing
assemblies.  Besides he said in the initial post that one (or some) of the balls were missing.
The simple fix would be to use a caliper and measure one of the remaining ball bearings and
buy some the same size and replace the missing ones which is what I said in my first
reply.
Life is only as difficult as you make it.    Allen
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PA0WV
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Posts: 141




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« Reply #19 on: October 24, 2011, 01:59:21 AM »


What?Huh??  Each ball is a ball bearing.  An assembly of ball bearings  and races are bearing
assemblies. 
Life is only as difficult as you make it.    Allen

Oh boy, now I understand the ambiguity; the laymans definition of a ball bearing is:

Quote
A ball bearing is a type of rolling-element bearing that uses balls to maintain the separation between the bearing races.
So that clears it up, because the picture shows a ball bearing integrated in the trunnion screw, that is about 1/4 inch or more diameter. And the topic starter said the ball bearing was 1/16 inch which is extremely small for a ball bearing.

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Using an appliance without CW is just CB
KF7IPW
Member

Posts: 47




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« Reply #20 on: October 24, 2011, 10:46:31 AM »

Thanks for all the help and hints.
I finally just bought an old key off E-bay (cheaper than the gas to go to the store!)
Swapped out the "balls" and it's working great.

Stan
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