My last posting turned out to be more about the bipod spikes than the black oxide experiments (in case you missed it: bipod-black-oxide. I had some more bits of tooling I wanted to finish, but those photos didn't really fit in with the last post so here's a quick rundown of some further black oxide testing.
Beadblasted and ultrasonically cleaned
These first parts are an extra long tool-holder I made for the lathe, the rivet setter from my kydex project posting, and a threading coupler for collet blocks.
Next is a fixture I made to turn a radius on the top of some 3/8" square aluminum parts. I didn't beadblast this one, lets see how the machined surface takes the oxide.
Into the drink they go
The small parts first. Heated in warm rinse water, dipped for ~3 minutes, rinsed, dipped again.
Fitting the tool holder in the 1 gallon bucket was a bit tricky. 1 pint of black oxide concentrate makes about 1 gallon of solution. If you're doing larger parts certainly mix up a quart at a time so there's some room in the solution. But it came out looking fantastic! This is after the post-blackening oil soak as well.
Rest of the parts complete
The rivet setter and lathe fixture both turned out excellent. I love the bead blast look on steel and aluminum, but the fixture shows me that a nice machined finish looks just as good with black oxide without the extra step.
That's all for now. I've got a backlog of fixtures and tool parts to be built, so I'll certainly be adding to the blackoxide photo collection in the future. The only question that remains for me is how long does the solution last? I've heard good things, it has certainly shown no signs of getting used up so far, but time will tell.