Hello, dear readers and DIY!
In this article, the author of the YouTube channel “Brian Oltrogge” will tell you how to cast a part from aluminum using a sample printed on a 3D printer. It also tells about the features of designing models.
A wall hook is taken as an example.
Tools used by the author.
– 3D printer
– Horn, crucible
– Set of needle files
– Spring clips.
The author has already modeled the future part, which will be used for casting from aluminum or other low-melting metal.
An important point is that one of the parts of the product should taper on all sides, acquiring a conical shape. More details about this will be discussed later.
All casting will be made in a two-tier collapsible mold.
Using a classic 3D printer with fused layer technology, he printed the model.
The first task is to remove small but visible layers and make the surface even.
Further processing can vary greatly depending on the type of 3D printing filament used.
If the type of plastic used is easily exposed processing with a solvent – then you can do without tedious sanding.
In this case, the master roughly smooths the surfaces using a file, file and 120th sandpaper.
After smoothing out the defects of 3D printing, the surface of the finished sample is covered with a layer of second glue. This will pick up the smallest dust residues and give the part extra strength.
Finally, the model is opened with polyurethane varnish.
This is how a full-fledged product turned out, by the appearance of which it is very difficult to say that it was printed.
Further, the author proposes a technology for obtaining a metal copy of the product, without damaging it.
To explain the nuances of design, the master had to make a test bench.
To create He cut out a strip of plywood for the central section.
Using a band saw, the part is U-shaped.
there will be booth walls.
Now the form is assembled, and its elements are fixed with spring clips .
The master specially printed several models with different shapes.
After mixing the sandy composition (about it later), it fills in the form by half.
Parts are installed in the upper part of the form, and the sand mixture is compacted around them. After a while, the composition will harden, and you can conduct an experiment.
So, when modeling, you should create a model so that it can easily be pulled out of the mold.
The first sample is in the shape of a trapezoid. Such an element cannot be removed without damaging the integrity of the injection mold.
The next layout, despite the fact that it has the shape of a parallelepiped, required some effort to extract it from the sand.
And finally, the third sample in the form of an inverted trapezoid is easily removed from the injection mold. As practice shows, even complex shapes are easily released if they are designed taking into account the correct draft.
Before you two views of sections of the same model of the wall hook in the perspective of the injection mold. They expand towards the top, along the extraction axis.
To create the mold, the author uses a mixture of building sand and silicate glue (sodium) in a ratio of 4: 3.
The author chooses this method to avoid calcining the mold in an oven.
The hardened sand is more like a cube of refined sugar.
The master covers the sample with talc, which facilitates easy release of the workpiece from the mold. This trick makes surface treatment easier.
Talc is also applied to the base of the formwork.
So, we begin to lay out the layers. There is no need to accept sand as we are just about to take advantage of its porosity.
The part is installed at the bottom of the formwork, and the composition is backfilled.
A sprue is inserted not far from the part. In this case, it is a simple pipe.
The surface of the mold is leveled. After flipping the shape, it will retain its even, flat outlines. Silicate glue hardens when exposed to carbon dioxide. It is advisable to leave the form outdoors for a couple of hours. The sprue needs to be pulled out.
When the mixture hardens, the mold should be turned over to allow the other side to cure.
Talcum powder is applied on top of the first part – it will prevent the wet sand from sticking together on the dividing lines of the forms.
A cap is put on the opening of the sprue to prevent sand from spilling inside. The remaining cavity will serve as a kind of chamber that improves the uniformity of filling the form with liquid metal.
A second formwork frame is placed on top, and a sandy composition is poured.
The next morning, the author opens the mold and, lightly tapping on the blanks, pulls out the samples. They separated perfectly, leaving behind perfect outlines for pouring.
To pull out the part, you can screw a self-tapping screw into it from the back.
The wizard now cuts a small groove from the sprue hole to the cavity left by the model. Don't make it too big. It is enough for it to pass a more or less decent stream of molten metal through itself. And although the shortest distance between two points, as you know, is a straight, slightly longer curved groove will help to cleanse the molten metal.
Then the furnace is heated up. Only propane will be used for this melting. Although the burner created by the master can also operate on diesel fuel, kerosene and even vegetable and industrial oil.
When the forge is hot enough, you can insert aluminum ingots into it. It is advisable to always have material with some margin. If something happens, you can always remelt it.
After the aluminum has reached the desired temperature, the author removes the crucible from the hearth with tongs and pours the hot liquid into the sprue. In this form, the injection mold is left to cool until morning.
Fortunately, such a composition easily breaks down in water.
This is how a newly removed cast part looks like. “https://usamodelkina.ru/uploads/posts/2021-08/1628895024_lit-240.jpg” rel = “prettyPhoto”> A sprue and a casting groove are cut from it.
First, the surface of the part is filed.
Next is sanding with 240 sandpaper.
Then the product undergoes wet grinding at 320 grit.
Finish polishing with diamond abrasive pastes .
All of these operations can be greatly facilitated by using the dremel .
Next, an aluminum plate is made with holes for fasteners. Paper templates make design much easier.
The aluminum plate is glued to the part with a two-component epoxy adhesive.
It remains to drill holes in the wall and hang the hook in its place.
Good mood, good health, and interesting ideas to everyone!
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Author's video can be viewed here.
Hello, dear readers and DIY!