Bronze: Sprues & Captive Rings

Still obsessively casting bronze.  I have a 19"seax and a 16" dagger both of which will get cast bronze fittings and sheath work.  Getting bronze to pour is one thing, and getting the objects to come out correctly is another.  It's largely a matter of spruing them correctly (making the channels for the metal to pour in).  People call it an art, but it's really a science.  It's all about hydraulic turbulence in the metal and cooling rates as the metal flows through the mold.
I decided to try a complicated casting this week.  One problem I've been encountering  in making the sheathes for my seaxes is the relationship between the sheath hangers and the rings they are connected to.  If you look at the two hangers below you can see the problem.  The hanger on the left looks ok, but it's function isn't optimal.  Because the strap exerts some sideways pressure the hanger tends to turn, even if the rivet is very tight.  The solution is two rivets, which is what I did for the sheath on the right.  But it has it's own problem - the ring doesn't fit over the hanger, so you have to carefully bend in the 'wings' on one side and slip the ring onto the hanger, then flatten it back out.  That is not going to happen with cast hangers.

I could make bigger rings, but they'd look stupid.  They'd be out of proportion.  I could split the rings and then solder them back together, but that's a bit of work and feels...  like it's too much of a compromise.  I've looked at the original baltic area seaxes and they solved the problem by making rings out of a couple of wire wound around a couple times.  It's authentic, but not what I'm looking for.

The solution I'm trying is sheath hangers with captive rings. What's a captive ring? It's a ring that can't be removed from another object without breaking the object.  What I did with both of them is create the hanger in halves in wax.  Then I took the wax ring and put it over the neck of one half, wax-welded the two halves together and voila!  a captive ring.

The big technical problem now is spruing.  The hanger & ring that are closer in the picture below were a success because the metal was delivered as directly as possible to the parts

The ring below failed to fill because the sprue to the outer ring was connected to the corner of the hanger, so the hanger essentially stole the rings metal.  By the time the hanger was full the metal had cooled too much for the remained metal in the pour to get to the ring.  Bummer.

Here's a shot from a couple ours later where I've gotten the spruing down.  Note the each sprue has one and only one destination:

Here's the final result - a nicely proportioned sheath hanger ready to install.