Ok, first time for me to try to alter the parting line from the flask split. I wanted to copy some punches in aluminum bronze and also test how well the aluminum bronze will flow. I laid out three punches, square ones on the diagonal, on a bed of sand in the drag. Rammed the drag and flipped it over and cleaned down to the parting line Dusted the surface and added a sprue Rammed the cope and separated the flask The pouring basin came out with the sprue. The cope looked good Cut gates And poured it. This is 90-10 home made Al-Br. It filled very well. I can read most the forged lettering. A little cleanup and they're ready to use. The long punch was a little rough on the small end but still very serviceable. I'm assuming the punches will work harden so I'm interested in seeing if they make durable punches.
Looks good. I need to look up "work hardened." Is that a DIY sand or the real stuff? I made my own last year, then got distracted. I wonder if it's still any good. Been sitting in sealed buckets.
Work hardening is what makes aluminum bronze tools not do this when you try to use them: However no amount of hammering on the edges will work harden the stuff enough for this to not happen when the blade somehow finds that one lonely hidden nail embedded in the tree you're chopping down: Jeff
I have some scrap C863 manganese bronze that I thought would be good for casting axe heads: as sand cast it's around 60 Rockwell A hardness and has tensile properties better than some hardened and tempered alloy steels.
Thanks man! Nothing special but I know there are lots of novices like me reading so I wanted to show how easy it was to cut to the parting line. Work hardened is a property some materials have, steel included. Cold finished steel gets harder as it is deformed during rolling, that is work hardening. Stainless steels usually work harden easily, that is why if you're drilling stainless you need to keep going. 304 stainless drills easily until you let up pressure o the bit and just mangle the surface. Then the stainless will work harden and get harder than the drill bit and will tear up the drill bit rather than get drilled itself. Aluminum bronzes are known for work hardening and Tobho Mott used that to good advantage making his ax. Generally when something work hardens it gets brittle as well. That's why the head of a cold chisel will chip after repeated uses, even though it started as soft steel. In my case I don't know the properties of home made 90-10 Al-Br so I am concerned that it may get very brittle with use and prove unsuitable for use as a punch. I'll find out. My sand is an internet purchase. When I was getting started I bought bentonite and have sand but I wimped out and bought prepared sand to eliminate that uncertainty as I was learning. It keeps me from blaming the sand for my poor work. Can't see why sand and bentonite would go bad, they were millennia old when you got them. A little mold just adds to the aroma of casting. I've enjoyed your adventures in aluminum bronze and it caused me to try to make my own. I'd be building a muller but I'm doing great just turning the heap so that's on the back burner. Sounds like good stuff. I've a machinist buddy who has some scrap aluminum bronze of various compositions but it's only several pounds so I don't want to try any until I have a good project in mind.
OIF, Looking at the price of punch sets recently, I'd say you probably just saved yourself about $50. Great job!