Difficulty melting copper

Discussion in 'General foundry chat' started by FKreider, Aug 26, 2019.

  1. Petee716

    Petee716 Gold Banner Member

    I have no experience at all with brass so I can't offer any educated advice, however I have a fair amount of experience with runouts. Weight on top of the cope or bar clamps will keep your cope from floating. It may not have floated on you this time but at some point it will, maybe next time. I generally use a piece of scrap wood over top of the mold leaving sprue an risers exposed, then stack a couple brake rotors on top or else bar clamps - not real tight, just enough to keep it from rising. I've clamped just the edges of the flask and had the sand heave on large flat castings and even though that might be rare, I keep it covered.

  2. Melterskelter

    Melterskelter Gold Banner Member

    Good point, Petee. One other convenient way to clamp cope to drag is to simply use small plywood tabs that bridge the seam and have a couple screws in one flask and one in the other. On the flasks shown I would use 3/8” or 1/2” plywood maybe 2” by 4” one on the front and one on the back.

    Such tabs do not prevent heaving, of course. If that is a concern, plywood boards can similarly be screwed to the top of the cope.

    Number 8 square drive pan head screws of appropriate length are quick and convenient. I drive them with an impact driver or , to avoid vibration on the mold, into pre- drilled holes with a screwdriver.

    I like the screwed-on patches as you don’t have the clutter of bar clamps nor weight of weights.

  3. FKreider

    FKreider Copper

    Interesting video from bigstackD Casting on Youtube this week, he compares 4 furnaces all running propane:

    It appears that the ceramic wool furnaces use less fuel and melt quite a bit faster than refractory cement furnace. Interesting.
  4. Jason

    Jason Gold

    Without seeing the video yet, I can believe that. Less mass to heat up. The trade off is undoubtedly going to be longevity and the lack of required maintenance. Ya won't find a professional bronze foundry with a kaowool furnace. Mizzou is some seriously tough stuff. Drilling it out is pure insanity. Not that there is anything wrong with a properly coated kaowool furnace, I just hate having to redo anything. One and done is my motto. I haven't touched my mizzou hot face since I built it and not a single crack! If that thing was kaowool, I would have rebuilt it 3 times by now.
    joe yard likes this.
  5. FishbonzWV

    FishbonzWV Silver Banner Member

    Why do you say that?
    You've never used one so you don't have first hand knowledge to quantify that statement.
    I've been using this type furnace and have never had any "rebuild".
    The Satanite has a higher temp rating than the Mizzou.
    The days of the draconian 200 pound behemoths are numbered! ;)
    Step into the 21st century :p
  6. Peedee

    Peedee Silver

    Depends how heavy handed and 'bullish' you are with it, If Jason kicks a furnace around the yard in a fit of temper then it may not fair so well? ;)
  7. FKreider

    FKreider Copper

    In the video the kaowool furnace does look a bit more "used" than the one with the refractory cement.
  8. Jason

    Jason Gold

    lol.. In the beginning, I know I dragged tools across that face. I've overloaded the crucible with stuff sticking out and rained bronze everywhere. I've seriously over heated a pot of bronze. (oil burner) A propane guy might stand a better chance. The only thing that has happened to my Mizzou is its turned a bit orange. Prior to working bronze, it was snow white. We need an ugliest furnace thread like we had at AA. Some of the pictures from the iron guys were hilarious.:D
  9. FKreider

    FKreider Copper

    Managed to get a good pour on my second try the other day!



    Next to the original casting that needed to be scaled up in size:
  10. Jason

    Jason Gold

    Looks good. Congrats! Did you cover the melt?
  11. OMM

    OMM Silver Banner Member

    It does look like you have achieved a good poor.

    I would like big stacked to do a cast iron pour with the same furnaces.... I would like him to also weigh the furnaces before and after.....
  12. Melterskelter

    Melterskelter Gold Banner Member

    What did you do differently this time compared to the first time?

    Very nice looking casting!

  13. FKreider

    FKreider Copper

    This time I had two BBQ tanks hooked up together and one of them was in a water bath. I also had more metal in the crucible so I as able to get a full pour.

    The crucible charge was made up of the previous casting along with some scrap brass. I have not tried to melt the copper wire again however I will soon!

    Next time I try to melt copper and zinc to make my own brass I will just be casting ingots for future use. I think trying to make an alloy and pour a casting all at one time is a bit much for a beginner like myself.
  14. HT1

    HT1 Silver Banner Member

    NEVER Just melt metal Never!!!! you have a Melt loss of 10-30% everytime you melt metal , and fuel furnaces are the worst . so you are just pissing away metal . make molds and cast . as to how to make brass

    you really need to make a simple heat sheet I shoot for 60 /40 brass 60% copper 40% zinc any thing else is less then one% and not intentional now I want a 30 Lbs heat what My crucible safely holds, I weigh out about
    20 Lbs scrap Brass,
    6 Lbs Copper and
    5 lbs Zinc
    the extra pound of zinc will be lost in the melting process
    now place all the Cu in the bottom of the crucible .
    cover it with Brass small pieces are best of course. the brass will melt covering and protecting the copper .if you have over a half crucible let it run wild til the copper is all melted. probe it with a steel bar, I use rebar it is cheap , but do not let it get above pouring temp, remember the copper is not really melting it is dissolving (but do not stir, you never stir metal) you add additional brass scrap from your weighed out 20 Lbs to keep the melt from over heating . you are probably looking for about 1100C for a pouring temp so try not to exceed this at any time.

    when the copper is all melted, you have to add the Zinc, the Zinc must be plunged to the bottom after thoroughly preheating it . this is not a step to skip it will get you burnt, how you plunge the zinc is a matter of it's form, I use Zinc anodes for Boats so they are round bar stock . I weld a piece of pipe that the anodes will fit in, to a piece of rebar, so I can Plunge the zinc to the bottom of the melt, I sometime get zinc turnings, I have made a Plunger http://mifco.com/shop/molders-tools-and-supplies/4-bell-plunger-35-handle/
    I wrap the turnings in the plunger using aluminum foil and copper wire ... you can just copper wire pieces of zinc to rebar, but occasionally one gets away from you , and you will make a huge cloud of zinc as the zinc floats to the top of the heat and vaporizes. once all the metal is melted check for temp and pour .

    now think about what you are going to pour, small ornamental pieces are the best, because if you have any issues they are easy to remelt. most everything I do is Small Ornamental Pieces so QED

    Good luck

    V/r HT1
  15. Jason

    Jason Gold

    I give that one a thumbs up and I hate brass! Even I could follow those instructions.:D:oops:
  16. HT1

    HT1 Silver Banner Member

    stop hating on brass Just because it causes you problems . But thanks for the support

    V/r HT1
  17. HT1, those are handy instructions: I have a stash of about 200lbs of zinc from recycled anodes that I plan to make into brass.
  18. HT1

    HT1 Silver Banner Member

    if they are exterior anodes, they are not always zinc, if they are military, some are actually quite exotic, closer to Zamak... they include aluminum and magnesium occasionally, but for plain ordinary "shiny" cast dodads who cares

    V/r Ht1
  19. Jason

    Jason Gold

    lol.. and to think of the 100lbs of zinc tire weights I have thrown in the trash seeking the lead ones.:D
  20. I'd heard of different anode metals, these seem to be all zinc if the pitting and powdery corrosion is anything to go by, the density is close to steel too. These were all melted down from used anodes over a gas burner so the temperatures wouldn't even melt aluminium. I used a steel pot which turns out to be a bad idea if you're trying to reuse zinc as a bit of iron will passivate the anodes and stop them working.

Share This Page