Aluminum Foundry Sand Casting House no. 25, 38

After my last few successfully castings using greensand I decided to make two new aluminum numbers for my house and for my parents in law. After casting the "diving plaque" I had more experience with this type of pattern. For the first pattern with the no. 38 I used 9mm MDF for the plaque base and my old metal numbers. I used plastic rope to create the plaque boarder.

The main thing with plaques is to create a good draft (angle) around the letters using some sort of filler that will be easy to sand and smooth that way the letters impression in the sand mould will come out in good quality without breaking the sand. Its important to get the sand mould correct the first time because plaques are all about good finishing, any casting defects are hard to fix and will be visible to the observer eye and definatly to a metal caster.

Using my new greensand I made the mould for the no. 38. The casting turned out well I just had a bit of grinding of aluminum flash around the plaque. I got carried away with the parting powder so that ruined a bit the flat surface around the number...... but that will be painted anyway ;-).

The second house number 25 was custom made from a-z, the base I made from MDF and also the letters. I used 8mm MDF to make the numbers so the numbers where chunky and needed a good draft around them. The last thing and VERY IMPORTANT, I used clear varnish for both plaques that prevents the sand from sticking to the pattern.

I almost thought the number 25 would have casting defects because I didn't have enough molten metal too fill the feeder on one side. To my surprise it was perfect. After cutting of the the sprue and riser and a bit of flash grinding I only had to give the numbers a good polish on the buffing wheel.
Last thing I drilled holes to mount it on the wall.
I used black gloss external metal paint for both of the number plaques and I polished the no. 25.
Both of them will be mounted on the wall of our houses for many years to come.

Aluminum diving plaque, foundry sand casting

This is a casting I made a few months ago as a gift for my sister. She is very passionate about scuba diving so I thought she might like this aluminum casting. I decided to make a round pattern for this casting and I used 9mm MDF as a base for the images and letters.
I started by using my electric router shaping an accurate radius from the 9mm MDF.
For this pattern I was trying to create a maritime/diving theme so for the plaque frame I used some plastic rope glued around the pattern.
After the rope was in place I used a filler to create a "draft" (angle), draft in sand casting means to create an angle so the pattern will not break the sand mould when lifting it out of the flask.

After the pattern base was ready I started designing the layout of the letters and images. For the letters I used children sticky foam letters, the letters works very well I used them before when I made my FlamingFurnace plaque casting. The images I got and printed are from the Internet, I glued them to 3mm cardboard and cut out the shape after glue dried. I live near the sea so from time to time my son collects shells on the beach so I used a few of them for this casting. The "challenging" shell was the spiral shape shell because I had to create the draft around it. I had to grind the base nice and flat to achieve that so I used my light-duty grinder and it was perfect for the job. At this stage it was just a case of re-arranging and marking every item to the exact location on the plaque. Gluing all the parts, creating a draft around each item with filler and finally and most important thing was to give the plaque pattern two coats of clear varnish. The varnish will prevent the sand from sticking to the pattern during the sand moulding process.

The sand moulding part was easy and successful without any sand breaking issues or other moulding problems. For this moulding I used Petrobond sand because I wanted to achieve a fine finishing for this specific plaque casting.

I used a large wooden flask with inner support ribs for this casting. As always I add a sprue and riser extension as it works very well and prevents aluminum casting shrinkage issues.
After opening the flask and removing the moulding sand I was really blown away at how great and detailed the plaque turned out.

The next part was to cut off the sprue and riser and clean a bit of "flash" (excess aluminum) around the pattern with a metal file. This is an important tip: aluminum alloy is soft metal and can be scratched and damaged very easily so when working with a vice its always a good idea to place the aluminum casting in a cloth and not directly in the vice, a cloth will prevent ruining your hard work. The only casting part that I polished was the letters, diver images and I semi polished the shells. The image with the spirit level below is just to show how flat the back of the casting plaque is with zero shrinkage thanks to the large sprue and riser.

The last and final part was to drill two wall mounting holes and paint the aluminum plaque dark blue.

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: