[Milsurplus] On the making of things (flex tuning cables)

[Mike Hanz]

On 9/18/2011 1:54 AM, Kludge wrote:
>
> While I'm not quite done with the electrical cable discussion, I'd 
> like to talk about something else for the moment, that being the 
> tuning cables.
>
> Unless I'm missing something somewhere, which is a really good 
> possibility, the spline adapters for both types of cable are identical 
> since both inner cables are identical.  This implies that if I can 
> find short or damaged lengths of Model D tuning cables, I have the 
> adapters I need to go on Type K and the later Type 12 equipment.  Off 
> the top of my head, I think I need around ten pairs to complete the 
> postwar systems.
>

Just to avoid cornfuzion, let me make sure we are talking about the same 
thing here.  I tried to use consistent terminology on the page at 
http://aafradio.org/garajmahal/flex_drive_cables.html for each of the 
piece parts because definitions seem to occasionally vary depending on 
the source document you are perusing.  The spline adapter, at least in 
my lexicon, is that short half hollow rod that goes between the inner 
speedometer cable and the female spline (or spline coupling if you 
wish.)  That little adapter is crimped onto the flex cable and is then 
held onto the female spline coupling by a 1/16" roll pin.  It is in fact 
identical on both the large and small tuning cable systems used before 
and during WWII, with the following caveat - although the inner flex 
cable seems to be quite consistent in diameter across manufacturers, I 
*have* run into a few female splines that are *not* the same inner 
diameter on the section of the splined coupling that accepts the spline 
adapter.  As a result, I recommended on the page above to find your 
splined couplings first, and then machine the spline adapter to match 
them.  Frankly, the female splined couplings are going to be the most 
difficult to locate.  The spline adapters take just a few minutes on the 
lathe and drill.


> The problem seems to center on the spline adapters.  After looking at 
> the drawings and pondering over significant quantities of caffotine, 
> it seems that they could be machined on my lathes out of any of 
> several metals.  While I prefer brass, I have it, stainless, 21L14 
> (which readily rusts unless coated) and I think some aluminum stock in 
> storage and some carbide 1/8" shaft router bits of unknown diameter 
> that can do nice things to the non-ferrous metals.
>

The originals are normally nickle plated brass.  I usually make mine out 
of stainless so I don't have to nickle plate it, but it doesn't really 
make much difference.  Well, on second thought I guess I would 
discourage the use of lead or balsa wood. :-)

> So what would be really convenient at this point would be the 
> mechanical drawings needed to create the adapters.
>

If we are talking on the same wavelength here, drawings for all the 
piece parts for both cable systems are on the link above.  Be sure to 
check out the new link in it that contains the WWII Philco assembly 
instructions, especially with regard to keeping the inner speedometer 
cable from unraveling.  KB4DMF would thrash me soundly about the head 
and shoulders if I didn't emphasize that point...hee, hee...

If there is any clarification needed on any the drawings, please let me 
know.  It's been over fifty years since I took my one and only drafting 
course, and my memory she ain't so good no more...

> All the rest of the fittings seem to be within the range of 
> capabilities of my machines although I need to do something about my 
> diamond knurling tool since it is for the Taig which I've taken out of 
> service for a variety of reasons.
>
> Have I missed anything critical or is this about right?
>

As amended, yes.

73,
Mike  KC4TOS