Casting aluminum bronze C95400

Discussion in 'Sand Casting' started by Tobho Mott, Aug 29, 2017.

  1. Tobho Mott

    Tobho Mott Administrator Staff Member Banner Member

    Ok, as promiseed, axe throwing!

    Also includes a bunch of footage of how I got the axe from a raw casting to its current state with the tools and knowledge I had available.

    Hope you guys enjoy the 2 minute long nerd-pun I used for an intro...

    Jason likes this.
  2. DavidF

    DavidF Administrator Staff Member Banner Member

    Looks like you got the swing of things LOL
  3. Jason

    Jason Gold

    Hilarious. Who's your barber! LMAO. That axe looks awesome! You planning on doing more weaponry? Hey.. Show your dog this one! I caught Oliver steeling my airport beater AGAIN!

  4. Tobho Mott

    Tobho Mott Administrator Staff Member Banner Member

    LOL, I don't want to give the little fuzzball any ideas... That reminds me of the old Elmer Fudd cartoon where he's dog-sitting and the dog escapes and winds up driving drunk. :)

    I would definitely like to cast more stuff like this. I might even know someone who might want to buy an axe or a blade of some kind. But I have to work the bugs out of the process first and figure out how to make one that's actually sharp. The axe held up like a champ to the tests I did in the part 2 video, there was no damage to the edge or anything, but it was never as sharp as I would have liked.

    Captain stupid here kind of ruined it trying to make it sharper though... I did a bunch more hammering on the edge then redid the grinding. Should have been more careful and patient; it got really hot on the grinder and I think this undid the work hardening. It did get really sharp, but when I tried some chopping, the edge got brutally mangled. Very quickly! Must have annealed it or something. Is that the word I want? This stuff is a little beyond what I have studied. It did change colours in one little spot on one corner of the edge - first a darker golden colour, then purple! The whole edge was completely wavy and rolled over when I was done the second test run...


    Ammen's 'Casting Brass' book hints that letting aluminum bronze castings cool inside the mold can result in needing to heat treat them, so if that is true it's even perhaps possible I undid a heat treatment that the casting had performed on itself! Not sure how far to trust the info in that book though, as some of it disagrees with things I have read elsewhere. I definitely did not shake it out as early as he says you should (ie. still red hot, and you're also supposed to brush all the sand off it too) to avoid needing to heat treat.

    Back to the bench I guess. I doubt I will be able to try the heat treatment, which seems to involve soaking it for 1h at 1600-1650F (higher than my thrift store toaster oven goes to be sure) for an hour per inch of thickness, quenching in water, then back in the oven at a lower temp for another hour/inch (though I am still very shaky on these details), so I'll see if I can grind the edge back straight and try more work hardening followed by a much more careful sharpening without extreme heat. I really hope I can find a good balance of sharp and hard enough to work well and be durable. If that doesn't do it, I guess it'll go back into the pot and I'll try casting it all over again. Still got 2 extra cores at least and my camping trip is not until the last weekend in September so I can get it done... maybe this time I'll be able to avoid getting the ugly defect in one side of the eye... I hope it does work though, I put a lot of work into this thing already!

    If anyone has any brilliant suggestions for fixing it other than what I've mentioned, now's the time!

    Last edited: Sep 11, 2017
  5. Robert

    Robert Silver

    Is that edge chipped or deformed? Could it be over-hardened and therefore brittle?
  6. Tobho Mott

    Tobho Mott Administrator Staff Member Banner Member

    Bad pic I guess, the edge was wavy shaped, more deformed than broken. I believe I overheated it and undid the work hardening. I had also ground it thinner than it was before. At first I thought I just made it too thin, but now I am pretty sure it was just the heat.

    I ended up grinding a little more off to straighten it back out (but not make it a lot less thin), then hammering the crap out of the edge again, sharpening it again, only going slow and easy using a file then some stones this time. It's now sharper than in the video where I was throwing it etc., and I was able to chop through the rest of the log in the pic far more easily than when I'd dropped the same little tree with it two days before. It cut great, and without any apparent damage to the edge.

    I gave it a few more throws too, seems easier to make it stick in now. I've never really had much skill at sharpening things, maybe I'm starting to to get better at it with a little more practice. Definitely can't shave with it or anything though...

    Seems just as durable now as before I ruined it, from what I can tell. I'm a little relieved I don't have to melt it back down or anything. :)

  7. Tobho Mott

    Tobho Mott Administrator Staff Member Banner Member

    I know some of you already saw it and commented, but here's another axe video, showing the edge's ruination in better detail, plus the results of more testing after I repaired it. IMO this is a great illustration of what work hardening can do...

  8. Jason

    Jason Gold

    I would have done the same thing and not thought twice about it. A day where you learn something new is never a wasted day!
  9. OCD

    OCD Silver

    Nice job Jeff.
    Agree with Jason's comment totally.
    A lesson learned it worth it's weight in gold.

    I think this will help sum it up for ya.

    Jason likes this.
  10. Tobho Mott

    Tobho Mott Administrator Staff Member Banner Member

    Thanks guys! I completely agree.

    Wranglerstar, eh? I think he must have 16 different 'right way to sharpen an axe' videos, all showing different methods. LOL... I think I have watched them all. I think I was actually even copying one of his axe sharpening videos when I turned on the belt sander! Also, I was creating this axe's original edge, not trying to to bring an existing edge back to useful condition. Still, his videos have been generally helpful during the this project, determining angles etc.

  11. OCD

    OCD Silver

    Take everything with a grain of salt.

    Sift through the pile (info) and pick out the gold, 86 the pyrite.

    Even the wise man on the mountain top can learn something from the Village Idiot.

    The purpose of attaching the video was that the head should have a certain thickness to it around the edge portion and be sharpened at a certain degree of angle for the edge to last.
  12. Tobho Mott

    Tobho Mott Administrator Staff Member Banner Member

    Gotcha, thanks again for posting it OCD.
    I don't think I that actually was one of the ones i had seen before. Maybe I'll make one of those jigs and see how close I got with just trial and error eyeballing it... :)

    Last edited: Oct 31, 2018
  13. Tobho Mott

    Tobho Mott Administrator Staff Member Banner Member

    The new C954 aluminum bronze pipe-hawk project hasn't belonged in the patternmaking section anymore for a couple of posts now, since it has already been cast!

    But first, a pic of the previous axe project in its element, the campsite during my annual late September canoe trip:


    A little backstory (aka the pipe-hawk patternmaking thread):

    Couple new pix, I now have all the flashing filed off (the bowl was a PITA) and the booger holes ground out:



    Still needs loads of sanding and also needs an edge ground on and work hardened. Hope to be out back chucking it at a rotting jack o'lantern or two within a few days. :D

    Drilling out the stem is something I might take my time with a little more. I only have two handles left, so I can only afford to screw up one of them...

    Last edited: Oct 31, 2018
  14. Woo!, lookin good!!. I wonder if steel shot blasting it would work harden it enough.
  15. Tobho Mott

    Tobho Mott Administrator Staff Member Banner Member

    I have no idea... my tiny little compressor could barely keep up when I used it to bead blast a couple of silicon bronze castings recently to prep them for patina. That is the entire sum of my experience blasting stuff with other stuff.

    I've made 2 Al-bronze axes before and used ballpeen hammers to work harden both of those. Made a huge difference!

    C954 supposedly can be hardened by heat treatment aa well though. Maybe when I get my kiln controls ordered and installed, I can use it to play around with that as well.

  16. Looking really good!
  17. You'd have to take to some professionals with a large compressor to run it, although people have made shot blasters with old ventilated rotor disk brakes: you spin it up to speed with a motor and feed the steel balls into the ventilation holes to be flung at the casting.
  18. Tobho Mott

    Tobho Mott Administrator Staff Member Banner Member

    Sounds like an interesting project...

  19. You would have to have balls to do that.:eek: Steel balls.:rolleyes:
    Tobho Mott and Mark's castings like this.
  20. Jason

    Jason Gold

    Very nice Jeff.

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