Welcome to my FlamingFurnace, backyard metal casting blog.

Hi everyone, I mainly focus on metal casting projects using recycled scrap aluminum and other accessories in the pattern creations.
Aluminum is a very versatile material and I would like to promote the awareness of aluminum recycling via different metal casting projects.

Feel free to check my YouTube channel where I provide detailed explanations, tips & tutorials for best backyard aluminum casting methods, homemade foundry equipment & of course the importance of safety when working with molten aluminum.

So remember recycle and Enjoy my blog ;-)

Friday, August 12, 2011

Oil Bonded Sand, Molding Aluminum Sun

Its been 3 months since my last post so I am back now with a few new aluminum castings and more tips and images. In this post I am showing my casting of an aluminum sun. This is a link to my first aluminum sun casting. The pattern I used for this casting was a clay sun that I varnished so it would be easier to remove it from the sand mould and to achieve a good finishing. For this large casting I made a new timber flask as you can see in the images. The flask dimentions are 390mm x 390mm x 80mm. Because it's a large flask this is a good tip to keep in mind: when working with such a big flask it is good practice to create inner "ribs" for the flask or just to make a few grooves with an electric router, any way is good. It is very annoying when you work hard on your sand moulding and just as you are about to place the cope on top of the drag all the sand falls out.

The sand moulding was very easy to make and I was able to lift the sun pattern without damaging the sun impression in the sand. The inner ribs also worked very well and the petrobond didn't fall out of the flask. I also got another bag of petrobond and in the images you can see the differance in the color. After many uses petrobond turns dark brown vs orange color for new petrobond.

My first sand mould was perfect but when I was finishing it I got distracted and forgot a very important thing, I didn't place my clamps on the flask. Here is a very important tip: The clamps or just a weight on top of the flask will prevents the molten metal from lifting the cope part (Hydrostatic pressure) and resulting in a pool of molten metal on the floor also burning the flask if it's constructed from timber. This causes a casting defect called FLASH (see flash image circled in red).
I made a lot of castings till this day and never forgot the clamps, so this can easily happen and can be very dangerous if you don't keep safety in mind. Because I always cast in the open on dry sand no harm was done. The only annoying part was to cut off, file and grind the casting FLASH. *** In the future I will post info explaining in more detail the most common casting defects***

My second casting was very sucessful, I didnt forget the clamps this time... :-)

On the top image 3rd from the left you can see the two sun castings. On the left is the sun from my first casting after cleaning the flash defects and giving it a bit of a polish and the right sun is the second casting which turned out to be a very good quality casting with zero defects. I drilled two holes in the sun and attached it on my garden wall with my eagle castings.

12 comments:

  1. Hello Aharon,
    First, you are doing great work and I appreciate how detailed your documentation is. Good documentation is terribly lacking in our hobby.
    Second, I am curious how well your refractory is holding up. Mine was only made of portland cement so I expected it to crumble after some use but I am looking for good long term replacements. Would you recommend fire cement or have you found a better alternative?
    Keep up the great work! Lost arts need to be found again!

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  2. Great creativity and I really like this and I also appreciate your creativity. Sun Moulding is very great and after attached it on garden wall with eagles it looks very beautiful. Thanks for sharing such a great creativity of yours.
    wood polish

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  3. Hi omnombluist, Thank you for you kind comment. I agree that there isn't too many sites that go into the depth regarding metal casting. I am very satisfied with my refractory. I used my new furnace for over 50 melts and about 2 hours each session. I use propane burner (no air blower) and the aluminum melts in 25-35 min every time. The refractory is a bit fragile and there are crumbling and cracks especially on the lid part. Good solution for fixing those cracks is too use Fire cement (ready mix). It comes in a tube same as the silicone tube and you can fill all the gaps and loose cement areas. After using the foundry the fire cement filler will dry and harden.
    If I would replace the refractory in my furnace I would probably weld another inner cylinder for the foundry and pack one layer of ceramic wool for insulation and another inner cylinder section of fire cement mixed with Portland cement. If you use only Portland cement it will crack very fast probably after the first use of the foundry. Good way to check if you foundry is heat officiant is placing you hand on the outside of the foundry after about two hours of use. If it feels worm that means its well insulated and if its boiling hot that means it not insulated properly and the foundry is loosing heat.
    Thanks again for your comment ;-)
    Regards Aharon

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  4. Hi howardproducts, Thank you for your comment
    ;-)

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  5. For the sand falling out thing, I noticed your flask is not very high. I saw a video where a company was doing molds and their flask was about the same perimeter dimensions as yours but about double the height. (Also much heavier) but maybe there's the reason...

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