Hi there, I’m planning to cast a part in aluminum 
Given how the legs are placed I fear the flow will no go downwards if I only pour through a pour basin and make a raiser on the opposite side. Could someone tell me how to make a vent, pour basing and vent for this part?
Thanks a bunch!
ps: The part is about 2.5 in across and those legs are 0.18 in at the narrowest place.
no casting expert, but I’m curious:
is this a “bowl” shape, as in, would hold liquid in the center in the position shown?
The inside is bowl shaped, yes. And it is meant to hold liquid.
You can do it several and the way I would recommend is to cast it inverted.
I am assuming a sand cast for this.
Make vent gates come up from legs that emerge from the sand. This will allow gas to vent and aluminum to flow through the legs. Vents trimmed after pour
Make the main pour go through the bottom and fan out to several places so the metal can flow fast all over and up the legs with minimize cooling. These will be trimmed off afterwards but will be what is on a flat surface.
You’ll also need vents for the ears or when you make the original pour holes have a couple branch off to it.
The biggest thing you want is to be able to pour fast so it gets everywhere before cooling and that any vapor (steam) can exit so you minimize porosity and voids from trapped spaces.
Any scheme you can do would work so long as it provides venting and avoid entrapped areas. I would do it this way because it puts the “high spot” on the bowl at the top, metal would flow into the low areas and then start flowing up the legs and the rest of the bowl.
My advice is worth what it cost!
Also, maybe a couple of x-shaped “sprues” to connect the four legs at the bottom and mid-way up the legs?
I’m curious, do we have metal casting equipment at the Makerspace?
We have a propane fired crucible. Talk to Fired Arts. You’ll have to provide the propane as we don’t store any on site due to fire code regulations (also why we don’t have oxy-acetylene welding set-up)
In short, yes. Fired Arts has this furnace, and it is used from time to time by Paul ( @Hardsuit ) to teach classes. I am unaware of the other activities surrounding it, but I hear tell there are some.
I am unaware of other furnaces if there are any.
Photomancer that is great advice and will help for future castings too.
I’m casting it on plaster. I have a part made out of MOLDLAY that I’m using as the positive. Once I melt it away from the plaster I’ll pour the aluminum.
I’m doing it this weekend and I’ll send pictures of it once it is done. Thank you all!
Some while back Walter did a Al casting project/experiment.
The following picts should give you an idea of the equipment used.
This has often been something that interests me. If anybody ever ends up teaching a class on it, I’d definitely sign up (hint hint).
Thank you artg_dms!
And I second benhubel statement.
And I’ll third that! 
Keep in mind when creating your master that you need to allow for shrinkage and finishing.
Shrinkage in cast aluminum is 5/32" per foot (or about 1.3%)
In addition, you should allow for additional material to be trimmed off to smooth/polish the surface after casting.
Allowing a 3% to 4% total oversize (in each dimension) is a good rule of thumb.
If using a 3D-printed model, you can simply scale it to 104% in KissSlicer before printing.
HankCowdog
I read that a couple of times and since I don’t have tight tolerances and I was feeling generous I scaled it up 5%.
Since this part is only 2.5", if I read that correctly, you might take a look in Jewelry/ Small metals. I taught a sand casting class last year using DIY greensand and I am working up a class for petrobond sand casting and Delft clay casting.
We are also getting an electric furnace for melting small batch metals. We also have a member that sometimes brings her personal electric furnace for casting classes. As the crucible is generally used for only one type of metal you would probably need to buy your own crucible.
If you can make a wax model of the part we can get up a lost wax casting class or you can make the original in the new 3-D printer to use instead of a wax model for investment casting.
Yeah-yeah-yeah… I hear you. Let me get the pottery and sewing stuff settled, and I’ll finagle something. Think June-ish…
I should avoid commenting with only five hours of sleep. Carry on. @_@
Did you ever cast this part? I’m interested in how the moldlay worked out for you.
well, for the life of me I can’t get the negative to work. I’m making it with plaster of Paris and I think I’m heating it up too fast. It starts collapsing after about 10 minuted of heating.
As far as the moldlay, it takes a while to get the settings right on the printer. I got it to be good enough but by no means clean like with PLA.
After several attempts I’m ready to pay someone to cast it for me. Anyone you know that does castings?
