Bell Replica Foundry Project

This aluminum bell casting project is relatively easy. As a pattern I used a small brass bell that is hanging on my workshop door for the last few years .

Making the mould is a very easy process but the tricky part is getting all the aluminum to fill the mould cavity. The bell pattern is about 3mm thick and as I thought it didn't fill properly the first pour.

The second pour I carved some of the sand off the cope part of the mould. This time the sand mould was filled properly. I like the contrast between the aluminum silver shine and the brass. Now I plan to make a back mounting plate for both of the bells.

Using my gas burner for the foundry it takes about 35-45 min for the aluminum to melt. I use all the scrap sprue and risers from the other castings, No aluminum goes to waste ;-)

Aluminum bell casting video:

Oil Bonded Sand Cating Large Aluminum Skull

In this aluminum casting I made a replica of a decorative plastic skull that I bought for €10. For the sand moulding I used petrobond and carved around the pattern. The main problem with the skull was its shape. I used filler to smooth "problematic" angles of the skull so that way it would be easier to remove the pattern without breaking the sand impression.

For this casting I also built a new wooden Flask because of the large size of the skull. I decided to reduce the weight of the aluminum skull by creating a hollow core. To form the core I just used an empty can of corn instead of making the traditional sand core.

The casting turned out well the only mistake is did was placing the corn can too high in the sand and that caused holes in the casted skull eye sockets.

I made a short video just showing how I removed the can of corn from the skull casting. It's a very easy proccess all that is needed is some sort of pliers to cut and pull the can out of the aluminum skull casting.

Video of me removing the can:

Green casting sand VS oil bonded sand

I decided after using oil bonded sand (petrobond) to test some homemade green sand. I got some play sand and after doing a bit of Internet research I started making the green sand. My goal was to make it at minimum cost and to achieve semi good casting quality ;-).
I started experimenting with small quantities measuring first 1KG of sifted and dry play sand. I used a mixer to grind the cat litter (clay) to a powder stage and then sifted 100gr (10% of clay), mixing both together and after just adding small amounts of water at a time. The process was very quick and the sand mix was ready after performing the squeeze test.

My first casting was an aluminum eagle. This was the 12th aluminum eagle I have casted and the result was very promising. No difference in the quality of the casting from the oil bonded eagle castings.

I decided to cast a bigger aluminum object this time so I casted my 3rd aluminum sun. The quality of the casting in this case was not the same. The oil bonded sand sun casting was with almost zero defects and the green sand casting was with a lot of defects mostly porosity. Perhaps from not ramming the play sand hard enough or from the lack of vent hole but again it's not the worst sand casting. I hung the sun on a garden wall and the defects aren't even noticeable it just needs a bit of sanding and polishing.

How oil bonded sand VS green sand:
Oil bonded sand produces a better quality casting but is much more expensive then green sand. Green sand is cheap, easy to make and re-usable. Oil bonded sand is stinky, smokey and stains everything it comes in contact with. Green sand is clean with no smell. Oil bonded sand is much more sticky then green sand. Green sand is alot more fragile then oil bonded sand.
If you are looking for amazing finishing on your casting use oil bonded sand. If you want a cheap solution for casting, for example some heavy machinery parts green sand will do just fine.

Here is a 5 min' demo video I made of how to make casting green sand.

Aluminum Spoon and Chicken Sand Casting

In this post I will show two castings that I made in one flask. I used two of my children's toys: a spoon and a toy chicken so I could engrave them as souvenir for them for years from now. I started by making the impression in the sand, I think I mentioned it before but the easiest type of pattern to duplicate for sand mould is a flat pattern. All that is needed is a bit of patience when digging out the sand after flipping over the drag part. It is important to carve around the pattern as far is its parting line to prevent breaking the sand when lifting the pattern out of the sand.

As I did mention before it is good practice to pre-heat any ingots or scrap aluminum before throwing it into the crucible molten aluminum. Two reasons, one: cold metal will "freeze" the molten metal in the crucible and second: to eliminate moisture coming in contact with molten metal if ingots where left in the wet. You can see in my foundry I used mesh on the top of the lid hole that works perfect for me. Very important to work safe with foundry gloves and pliers when lifting and placing hot ingots into the crucible and also face shield protection.
In one of my visits down the beach I found a pressure cooker lid washed ashore so that happily got a new "life" in my crucible and I also melted my sons broken scooter ;-)
The last image is scrap aluminum from my old electric router and sander. What ever scrap is to big to fit into my crucible it ends up chopped up or broken with a heavy hammer but they all end up as nice ingots ready to become a new object.....

In the next images you can see the aluminum spoon and chicken turned out very well and all the left over aluminum turned back into ingots.

The sprue and riser did their job and you can see in the image that the casting was "feeding" from it while it was in the solidifying stage. After cutting off the sprue and riser I gave the casting a bit of cleaning with a metal file. Then some light sanding and polishing on the buffing wheel.
Now its ready for custom engraving.