Dave wrote:

"Ian White GM3SEK" wrote in message
...
Owen Duffy wrote:
Ian White GM3SEK wrote in
:

Alternatively, wind the wire onto a mandrill.

Or would that be a mandrel?


I've seen both spellings recommended in print, but winding wire onto a
mandrill will be far more entertaining.


OK, this time it's serious (well, mostly)...


The original meaning of "mandrel" seems to have been a rod-shaped tool,
onto which metal can be forged or glass can be mo(u)lded. The mandrel is
removed to leave a shaped cavity, and the mandrel can be used again.
This meaning is obviously very old, and would have crossed the Atlantic
with the Founding Fathers.

In the more recent context of coil winding, a mandrel is an object onto
which the wire can be wound. Again, the mandrel is always removed - it
is a tool, not part of the finished coil.

Some dictionaries note an alternative spelling, "mandril". This is an
old English dialect pronunciation, just like "chisil". (I don't know any
dialect-speaking blacksmiths, but can attest that "chisil" is still very
much alive.)

The confusion with "mandrill" comes from the fact that a convenient
mandrel of known size is the shank of... a drill.

The consequences of winding wire onto a mandrill - or indeed, onto a
ferret - are Nature's way of punishing engineers who can't spell.


Dave said:

what i have seen is a 'coil form' is something that remains inside the coil
once it is complete. a 'coil former' is a removable frame or device that
you wind the coil on and then remove. These can be for large coils that are
then supported by something else, like tank coils in amps. Or for coils
that are then put on a core that is built separately, as in a high voltage
power transformer.

That's completely different from British engineering usage. We don't use
"coil form" at all. "Coil former" almost always means something that
remains inside the completed coil. If it were meant to be removed, that
would have to be made clear from the context.


Cross-posted from rec.radio.amateur.etymology. We now return our antenna
readers to Prior Art.


--

73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek