Ian Iveson wrote:

BTW, R-core is claimed as a trade mark by

http://www.kitamura-kiden.co.jp/english/

who reckon they introduced it to the world in 1978.

Yes, I believe that is correct. R-cores are also made by other suppliers under
license.


Why do they say it is round when it isn't? Presumably they mean rounded. The
cross-section is a rounded diamond shape, by the looks.

The cross section of the core itself is indeed round.


It may follow that the exact method of manufacture is unpublished. They have
loads of patents, they say. Is there anywhere on the net I can get copies of
patents for free?

If it's a US patent they are certainly available for free. Just Google.


Perhaps you, or anyone, can take a look at the core in this pictu

http://www.icl.co.jp/audio/english/RX40.htm

and suggest exactly how it is made. My guess is that the final forming is done
with a press, and I still can't see how it holds its shape unless the strip is
bonded along its whole length.

It's probably formed by winding on a mandrel I reckon.

Graham