K3 VFO A tuning knob set screw

[John Gibson]

I currently am assembling my new K3 #820 and have reached the step where I
need to mount the VFO A tuning knob. I am unable to advance the knob's set
screw far enough to clamp the knob to the shaft and am considering running a tap
in and out of the hole to clean up the thread.

Does anyone know the diameter and thread pitch of this set screw? If I hold the
screw against an 8-32 tap, it seems to fit, but I am worried that it might be a
metric thread instead.

73,
John, no8v


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[John Gibson]

Hello Thomas,

I can use the allen wrench to extract the set screw from the VFO A knob. When I
hold the set screw against my 8-32 tap, the threads mesh, and the diameters
appear to be the same.

Even though the set screw thread meshes with that of my 8-32 tap, the set
screw is not long enough to make me feel certain that they are the same, rather
than merely being "close." I am not familiar enough with nominal metric threads
to know whether there is one that is close to 32 threads/inch.

There is an identical set screw in the VFO B knob. Either set screw will thread
easily into the VFO B knob, but either set screw will go just so far and then bind
in the VFO A knob.

73,
John, no8v

---- Original message ----

>Date: Sat, 3 May 2008 21:26:04 +0200
>From: "Thomas Norff" <[hidden email]>  
>Subject: RE: [Elecraft] K3 VFO A tuning knob set screw  
>To: <[hidden email]>
>
>Hi John,
>
>i am living in 'metric land' and i'm shure this is not metric. I had to use
>the alan wrench delivered with the K3.
>Can you see the screw if you look 'into' the knobs hole for the shaft ?
>
>Never heard about issues with this item.
>
>73 Thomas, DM7TN

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[Vic K2VCO]

John H Gibson wrote:

> I can use the allen wrench to extract the set screw from the VFO A knob. When I
> hold the set screw against my 8-32 tap, the threads mesh, and the diameters
> appear to be the same.
>
> Even though the set screw thread meshes with that of my 8-32 tap, the set
> screw is not long enough to make me feel certain that they are the same, rather
> than merely being "close." I am not familiar enough with nominal metric threads
> to know whether there is one that is close to 32 threads/inch.
>
> There is an identical set screw in the VFO B knob. Either set screw will thread
> easily into the VFO B knob, but either set screw will go just so far and then bind
> in the VFO A knob.

Just get a long screw that you know to be 8-32 and run it into the hole
in the knob. If it goes easily (at least up to where the thread ends)
then it is probably 8-32.
--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco
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[KM5Q]

John,

If the threads of your tap mesh the screw, then the screw is NOT metric. Metric size is noticeably different. If your tap's diameter also matches, I'd go for it.

Windy KM5Q

[John Gibson]

Earlier I wrote:
----------------------------------------
I currently am assembling my new K3 #820 and have reached the step where I
need to mount the VFO A tuning knob. I am unable to advance the knob's set
screw far enough to clamp the knob to the shaft and am considering running a
tap in and out of the hole to clean up the thread.

Does anyone know the diameter and thread pitch of this set screw? If I hold the
screw against an 8-32 tap, it seems to fit, but I am worried that it might be a
metric thread instead.
-------------------------------------------
I now can report that I took the bull by the horns and used my 8-32 tap to
clean up the set-screw threads in the VFO A knob. The 8-32 set screw then
went in smoothly, and the VFO A knob now is mounted on the VFO A shaft
encoder.

I ran intro a different problem with the VFO knob. The knob would not fit on the
shaft, and I also could not insert a 1/4" drill bit shank into the knob. I then used
a 1/4" drill bit to gently ream out  the knob, and it now is mounted on the VFO B
shaft encoder.

Thanks to Thomas, Vic, and Windy who were kind enough to respond to my
request for help.

73,
John, no8v
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[John Gibson]

I should have said "I ran into a different problem with the VFO B knob . . ."

John, no8v
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