[Boatanchors] 1/4" to 1/8" Knob fix

[Richard Knoppow]

    I've had this problem in the past when I needed knobs to fit 
Hallicrafters S-40A and S-38 (no letter) BFO shafts. In both receivers, 
and I think some others, the BFO shaft is a threaded end of the core 
that adjusts the frequency. The original knob is a 1/8" one that fits 
over the small shaft. There is also a tab bent out of the chassis to act 
as a stop. I was unable to find replacement knobs so I made inserts from 
plastic sleeving cut away for the set screw to fit through. The original 
knobs have a fin (can't think of the right word) to hit the bent out 
tab. I just left it off. I think the shaft inserts shown in the post 
would work fine in a standard Hallicrafters knob with a bit of plastic 
glued inside the knob skirt to work the stop. I think I will try this 
although the present arrangement works OK. I am glad to know this 
resource exists. Thank you.
     I suspect there are a lot of applications for a similar insert.

On 3/28/2026 11:22 AM, hwhall--- via Boatanchors wrote:
> Late suggestion: Maybe you can find a nice pair of 1/8 knobs with hefty metal inserts in which one can be bored out to 1/4 inch? I've seen some knobs with thick enough inserts & bored a few out in the past.
> 
> Wayne
> WB4OGM
> 
> 
> On Saturday, March 28, 2026 at 11:59:23 AM MDT, Doug Hensley via Boatanchors <boatanchors at mailman.qth.net> wrote:
> 
> Thanks to everyone on the list.  Suggestions received & I'll let you know in a few days how it worked out.
> 
> Vy 73,  Doug W5JV
> ______________________________________________________________
> Boatanchors mailing list
> Home: http://mailman.qth.net/mailman/listinfo/boatanchors
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Boatanchors at mailman.qth.net
> 
> List Administrator: Gary Harmon, K5JWK
> ** For Assistance: gharmon at idworld.net **
> 
> 
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to 1oldlens1 at ix.netcom.com

-- 
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998