[R-390] How are your knobs ?

[quartz55]

How about a bronze sleeve bearing 5/16 (.312) id, 7/16 (.437) od 1" 
long.  McMaster 6381K446.  Drilling the hole on mine at .55 would not 
leave much material.  0.437 would work though.  Drilling out an E-Z Loc 
may work too if you could find one long enough.

Dave
N3DT

On 5/15/2014 3:47 AM, Pete Williams wrote:
> ​.. G'dsy..... in the process of restoring/rejuvenating 390s'over the years
> . I've been blessed on   few occasions with broken fingers on the  kHz and
> Mhz  knobs
> To get proper functioning  and  everything looking right, I got me  a tame
> machinist./turner  with lathe  and  such.
> I don't  know if this has been  documented on this  list but the procedure
> and   work done was  as follows .
>
> .!.. The inside of the  knob where the fingers  and web meet  at the
> shaft 5/16" (0..312) hole is  drilled out to about 0.55"and down to the
> bottom of the shaft hole.
>
> 2.  A  brass insert was turned up 0.95 " long  with OD of 0.55" for  a
> snug fit in the  drilled hole . The ID of this insert is same  as shaft
> diameter 0,312. and has a wall thickness of  about 0.12".
>
> 3. The insert is held in place with a coating of metal adhesive--- one of
> the  cyanoacrylate  type  and  I was assured this will  never let go.....
> and never has  either.
>
> 4. two holes  were  drilled on the  outer lip of the  knob  and holes
> drilled into the brass insert  of  appropriate   diameter to b e tapped
> and take the usual Bristo  set  screw. These holes  were  set 90 degrees
> apart to  prove for   ample  holding ability. The length of the protruding
> insert from the hole is  about 0.4 "--- approx. same as the length of the
> 4 fingers from the  web.. Set screw holes positions  located as in original,
> Has worked well with no problems.....
> I've taken some close up pics of the knob  and  can email off to any
> interested.
>
> Pete VK3IZ
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