Silver soldering/ CU tips please

[emeritus]

You could try the bus bar joining technique that I recently found mentioned in a 1944 text book and posted on another thread, which is to rough file the mating surfaces under Vaseline and then bolt together without removing the dirty Vaseline. It is said to give very low resistance equal to soldering. See pages 701-702, a technique devised for joining aluminium bus bars, but applicability to copper bus bars mentioned at the top of page 702. No personal experience, other than in using Vaseline to ensure good connections to car battery terminals.