I have had a few problems with making two parts that have a hole on each end of the rods, where the holds must end up exactly the same length.

My procedure was to drill and part of the ends for the rods, and put a counterbore in the side where the rod will go. The rods were created and machined to length, I made a jig so the rod ends could be located with the rod between them, assembled with flux ready for silver soldering.

Once silver-soldered, which seemed to go OK, I struggled to get the parts off the jig, to the point where the joint failed. The parts showed no signs of having being soldered to the jig, I assume it was flux or other "scale" created during the heating.

Questions.

1. What clearance should I have on the jig to allow for expansion/contraction?

2. Will the jig cause the joint to be weak as the part is put under tension as the rod cools and shortens?

3. If I was using free-cutting steel, would that cause an issue with silver solder? I know lead in steel can cause issues when welding & soldering to brass alloys with lead in.

4. Am I better off drilling the rod ends undersize to start with, then opening them out later using a slot drill to get exactly the correct spacing, allowing a bit more movement within the jig?

Unfortunately I can not put a picture up as I was going to re-do parts so took a file to the solder.

Baldric.