Introduction

Discussion in 'New member introductions' started by Pedro Ruela, Jul 7, 2020.

  1. Pedro Ruela

    Pedro Ruela Copper

    Hello everyone,

    I am from Portugal, I am relatively new to foundry. Have been melting brass and losing it in a forge . Because my crucibles are made of 100 x 100 mm x 5 mm square tube with a slice of 30mm flatbar welded all around with a lid (I know I need a proper graphite crucible, and a furnace) . It took me 4 painful melts and 3 crucibles to realize that the tube cracks at around 1100° pouring all the brass onto the charcoal. Only the first melt is doable. After that it cracks. Tried aluminum, it melts quicker than water boils. Anyway I believe there are threads to share our learning misfortunes.
     
  2. Petee716

    Petee716 Gold Banner Member

    Welcome Pedro. Many of us have had our own bad experiences with steel crucibles. I've never heard of anyone having any real success with copper alloys using a steel crucible. Although you can get away with aluminum for awhile, either oxidation from the outside (especially in a charcoal furnace) or the aluminum eating away at it from the inside, they dont last and often end in disappointment at best, or disaster at worst. But for those who have made these mistakes and learned from them, there are many great successes.
    You'll like it here!

    Pete
     
  3. Jason

    Jason Gold

    Welcome Pedro. What are you making?
     
  4. Pedro Ruela

    Pedro Ruela Copper

    Hi Jason,
    I am trying to cast 2 missing post office mailboxes
     

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  5. Pedro Ruela

    Pedro Ruela Copper

    I know this is a forge not a furnace, but I had to start somewhere and also it is not a crucible :)
     

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  6. Jason

    Jason Gold

    Time to build a furnace. That part looks pretty easy from what I can see.
     
  7. Pedro Ruela

    Pedro Ruela Copper

    Definitely, I am just having trouble getting some refractory for it. I have an unlimited (so to speak) amount of oil to burn, I work in my family's construction equipment company. We have a 2000 liter deposit full of waste oil that every month we pay to have it "recycled"
     
  8. Jason

    Jason Gold

    Firebrick is another option for you guys that cant find proper castable refractory cement. Whatever you do, do not use ordinary cement, got it??
    I too have a bottomless supply of used oil. If you own an aircompressor, even a little 20-30gallon will work for this, you might want to look up the Kwiky all fuel burner.
    It can be built with off the shelf parts from your plumbing store. Start it on diesel and when your furnace gets hot, you can make the switch to use motor oil. Propane can also be used in
    this burner for preheat if you can't get diesel. (Which I highly doubt) Take a peek at my youtube channel in my signature and you will see this burner in use.

    Dave is the father of this great little burner. Here he is.
     
  9. Tobho Mott

    Tobho Mott Gold Banner Member

    Welcome to the forums!

    This is very doable. Some good ideas and suggestions above already.

    It could be worse - my blacksmith friend had to completely rebuild one of his coal forges that he burned out trying to melt a #6 crucible of copper in it...

    Can't find where to buy good refractory? Here is a diy recipe you might be able to find the ingredients for:

    https://www.backyardmetalcasting.com/refractories.html

    Don't let the portland cement ingredient throw you off, Jason is right to point out that stuff isn't refractory - it will fail at high temperatures. But in this recipe I believe its only purpose is to help hold the mix together until the furnace gets fired, at which point the clay ingredient takes over.

    There's a chance the perlite could melt after many uses (or even one super hot melt), but many hobbyists have used this recipe for aluminum/brass/bronze and had it last for years.

    You could even skip the insulation and just ram up a sand and fireclay wall as described in David Gingery's book, The Charcoal Foundry, but that would be a big heat sink that will take some time to heat up. Good for a charcoal furnace though, because solid fuel self-insulates... and some here have built waste oil furnaces to be dense rather than well insulated, and they seem to like them so maybe you would too.

    Honestly though, if you are only casting one mailbox, the first thing I might try would be to place a chunk of steel pipe or tubing on end in your forge, centered on where the air comes in. This would act as an improvised charcoal furnace, allowing you to build a deep bed of coals below the crucible and pile more coals up where they are in contact with the sides of the crucible as well. The only thing missing would be a lid. That might not help much, but all you have to lose by trying it is a little charcoal.

    Of course, nothing will perform quite as well or be as durable as real commercial refractory and suitable high temp insulation, if you can find it.

    Good luck!

    PS. The same site I linked above has a couple other proven homemade waste oil burner designs detailed on it, if you poke around a little. Look for the Brute and the Hot Shot. These drip injector burners can be built cheap and easy and don't need an air compressor to run, but they do need the furnace to be preheated red hot (usually using just a little propane, but whatever works). Some people prefer a spray nozzle burmer like the Kwiky all fuel burner in the video above and on Jason's youtube videos, or a commercially available Delevan nozzle, while others like me swear by the drippers. I've got posts here and also some YT videos showing how I built and operate mine. I suggest taking a look at both types of oil burner and see what you think works best for you.

    Jeff
     
  10. Pedro Ruela

    Pedro Ruela Copper

    Hi Jeff,

    Thanks for your reply.
    It has a lid, otherwise I couldn't melt before the steel bottom started melting too. I bought a nice book the artful bodger's iron casting waste oil furnace.
    From a really nice guy called Colin Peck.
    Thru his website http://www.artfulbodgermetalcasting.com/
    I am a welder/locksmith/everything to do with metal.
    I am restoring and old mail box, and when I went looking for a foundry, all I could find is a guy that casts aluminum, and big companies saying "talk to us when you want more than 1000 pieces"
    So I decided to start casting stuff, has hobby and possible business. cobut in the future I want to cast iron. (the box is cast iron) And crazy objective to cast stainless (I know it needs vacuum or some sort of device to keep oxygen from the top of the crucible while it melts, and slow cool down). For now I would be happy if I can build a furnace to melt about 20 kg of iron, when that works, a bigger one for 100 kg. I have access in shop to a multitude of tools, forklifts, an air pipeline with 10 bars.

    Here are my first 2 pours (brass) . The first no vents or top, the second vents, no top
     

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    Tobho Mott likes this.
  11. Jason

    Jason Gold

    You're close. Can you get petrobond? Or are you making your own greensand?
     
  12. Pedro Ruela

    Pedro Ruela Copper

    I actually inherited the sand from a 95 year old, who gave it to my uncle a few years back. Unfortunately, only the sand and boxes, not 1% of his knowledge.
    But I found a company that sells foundry equipment and also greensand in the north.
    The mold is weird because, I didn't realize then that the sand needs to have some moist in it. It was too dry. Before I found that out, the only way I could get the mold to get all details was putting baby powder has parting and plastic film (never seen any suggestion for it) but apart from everything being a bit more round. It actually worked well. I was trying to upload videos of the pours, but even downgrading it to the lowest resolution (8mb file) it still says it is too large, so I did some screenshots of it . Here is the 3 cast (already with top and vents) and (last brass, aldo since it was with pieces I got from the charcoal, it split some of it to copper, weird but really good looking alloy) and finally the 4th with aluminum. And this was a few days ago. Found a lady selling a A30 crucible in my town, trying to speak to her.
     
  13. Jason

    Jason Gold

    I was going to ask you... Why are you screwing with brass on this thing? Is this just practice for iron? You might want to try bronze instead. No drama like that nasty stuff you are pouring there.
     
  14. Pedro Ruela

    Pedro Ruela Copper

    Because, the original frame is brass, which I will have to cast too, I originally tried to secure the small door (which is cast iron) to the frame and cast the whole door has a whole, but couldn't do the mold (that was before figuring out that sand needed to be a bit humid).
    It seems too fragile in aluminum, I can't melt iron, and I have some brass, tons of steel, very little bronze, but now that you mention, brass melting point is about 100°
    higher than bronze, maybe my steel crucible can handle that. What do you think?
     

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  15. Petee716

    Petee716 Gold Banner Member

    I have Colin's book too. As I mentioned there are many success stories here, and that goes for iron casting too. Colin doesn't participate here but his furnace is tried and true. I've used some aspects of his design but not all of it. My burner and refractory are different than his. There are a number of successful iron casters here.
    Once you get your greensand right you will be surprised at how well it performs. If it was good before it'll be good now. Start with about 3% water by weight. Mix it thoroughly with a trowel or shovel. Pick up a handful and squeeze it into a sausage shape with one hand and break it in half. It should break off somewhat cleanly. You can look this proceedure up on YouTube. Greensand sausage test. Because your sand/clay mixture is so dry let it sit overnight (covered) to let the water really slake into the clay. Then try the test again. You will probably have to add more water but do so with a spray bottle and go easy. It is far easier to add water than it is to dry it out!
    I'm not sure what an A30 crucible is in Portugal but I suspect it is way way too big for your present (and probably near-future) needs. An A10 (10kg bronze) is a good starter size. One for copper alloys and one for aluminum. Checkout that supplier you mentioned. Once you decide on your crucible, then you can reasonably decide what you should do about building your furnace. If you plan well you might be able to get everything in one trip. It will cost a bit to get started but once you get going it's not bad. Free fuel is the best!

    Pete
     
  16. Pedro Ruela

    Pedro Ruela Copper

    This is the crucible, it is huge, but 50€ it is a bargain, the other I found for sale is for 4 kg only, and costs 40, unfortunately the lady put the ad almost 1 month ago and hasn't returned to OLX (it's a selling app).
    One thing Colin refers in his book, is that if he was to build bigger than what he has now, he would add a 2nd burner instead of increasing the size the original burner, anyone here with a multi-burner furnace? If yes, where would the 2nd one be located? On the opposite end? Or I can mail Colin and ask, he is always very helpful.
     

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  17. Petee716

    Petee716 Gold Banner Member

    I wouldn't tell you what to do but consider the following with the A30:
    -If you're burning oil you want your furnace bore diameter to be around 100mm larger than that. That's big.
    -You need to make or buy lifting and pouring tools to fit each crucible size you use. There's no getting around that.
    -A30 is a size and weight too large for one man to pour alone without special equipment (which you can make).
    -Although I can't verify the information I've been led to believe that crucibles like to be full as opposed to 1/2 or 1/4.
    Some of these issues can be overcome but the extra labor hardly seems worth it.
    I don't have a double burner but my delevan siphon nozzle with 2.5" pipe will provide more than my 10" furnace can handle.

    Pete
     
  18. Pedro Ruela

    Pedro Ruela Copper

    That tiny bit, unless I use film gets stuck and screws the mold all the time, :mad:
    Any tips?
     

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  19. Pedro Ruela

    Pedro Ruela Copper

    You are right Pete, but I don't plan on buying the huge one and use it for all purposes. I will buy smaller ones too.
    Now the furnace, so for a oil burner, the diameter should be 100 mm bigger than the largest crucible, I intend to use? No matter the size or it should be more when it gets bigger? And what is the highest temperature refractory you can get 2000°?
     
  20. Jason

    Jason Gold

    Mizzou is 2600.
     

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