![]() ![]() ![]() Rather than being square, the edges of the cuboid pattern must be ‘drafted’. instead it would have to look more like so: If, for example, you wanted to make a simple cuboid shaped pattern, you couldn’t make it a true rectangle. The draft angle is the angle you need to allow on the edges of the pattern so that you can actually pull it out of the sand. The two main additional considerations are draft angles and parting lines. Making a pattern for this method requires a bit more thought than lost foam. The pattern is essentially a duplicate of the part that you want to cast. Once you have your green sand, and have tested its consistency, before you can ‘ram up a flask’ (make the sand mold) you will need two other things: 1. I use a pump action mister sold at garden centres for misting plants (comes in handy for plastering jobs, misting concrete, and settling dust too, so is quite a useful workshop item anyway).Ĭheck out the little video to see how I make green sand. A mini sand pit type thing is ideal as the large surface area lets you add water more evenly, reducing mixing or ‘mulling’ time. Other things you will want to make green with sand are: Green casting sand: 90 percent very fine beach sand, 10 percent bentonite clay. An old liquidiser does a good job here, as do scrap coffee grinders, either of which can usually be salvaged from trash if you keep your eyes open. The cat litter does require grinding to make the clay fine enough to be evenly distributed in the sand. I used cat litter, which is a very cheap source of bentonite clay (also referred to as “Fullers Earth”). Making the green sand is quite simple, but time consuming. It is used to form a mold into which is poured the molten aluminium. The ‘green sand’ in green sand casting isn’t really green, it is a mixture of bentonite clay, fine beach sand, and some water. The pattern is either a sacrificial foam shape that gets burned away by the aluminium, or a wooden shape that is used to create a hollow in the ‘green sand’. The current setup has evolved to use a shop-made propane burner plugged into the same original furnace, and a big graphite crucible from e-bay.īoth methods involve making a “pattern”, in the shape of the finished part. That lasted quite a while, but eventually burned through. To begin with I used charcoal as fuel and a stainless steel crucible – an old wine ice bucket we found in the trash. It’s really quite rough and ready made in the ‘Gingery’ lift out crucible style. ![]() My furnace is made from an old steel gas bottle lined with home-made insulating refractory cement. The DIY Propane furnace, lid off, melting some scrap aluminium.īoth methods involve heating up scrap aluminium in a DIY furnace until it melts, which is roughly 660 oC, 1220 oF. ![]()
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