Here's a quick project I did today:
These are brackets for an exercise machine. It has a design flaw and a bolt keeps breaking (fatigue failure at about 1 million cycles, which is every couple months with the use it sees). The original brackets are thin webbed die castings, so I can't drill them out for bigger holes. Instead, I stuck some pieces of pipe through for core prints, used electrical tape to cover the webbing and fillet in the core prints, and I'm molding them up to cast some solid ones.
Drag flipped and coped down, ready for the cope to be rammed. I am working with zero draft on these patterns, but it's easier to deal with bad patterns than to make a good one when I'm only casting two pieces.
There's the mold, cores inserted (rammed up in a scrap of pipe, again zero draft), and ready to close and pour. I do have some crumbled edges from the lack of draft. I rammed a little lighter than normal, which will make a rougher surface finish, but it also allows me to rap those patterns side to side and get enough clearance to pull them without breaking the mold.
And poured. This is generic Si casting alloy, melted in a steel crucible. No flux or degassing, though I did inoculate with Sr and Ti-bor (modifier/grain refiner), as I will be machining these without heat treatment.
Not five minutes later, after shakeout and quench. That Si alloy is very fluid--I guess I'm getting too used to casting with 6061. Both castings came out fine, the surface finish is nothing exceptional, but it'll work for what I'm doing.
Some judicious bandsaw and grinder work yields these semi-finished castings. I got a little over-happy with my gating and risering there--the Si casting alloy hardly shrinks at all compared to 6061, so I really didn't need all that. Probably two pounds of gating for half a pound of castings. Those little divots are not shrink defects, that's where the tape spans the hole in the casting.
Machined. Unfortunately I didn't get any pictures of machining, but it was pretty basic, using a three-jaw to grab for one bore, then flipping it around and CA glue onto a fixture to hold for machining the second bore.
And installed. Gone is the wimpy 6mm bolt, replaced with a 3/8" bolt. And if that messes with me, I'll drill it out again and put a grade 8 1/2" bolt in there, because now I have the meat in the casting to do that.