Creating a simple part with Part WB/pt-br

Introdução
Esse tutorial tem como propósito ser uma primeira introdução à modelagem 3D usando a Bancada Part do FreeCAD. Ao finalizá-lo você vai conseguir produzir modelos 3D simples usando primitivas como cubos, cilindros, etc, com a técnica de modelagem chamada Geometria Sólida Construtiva (ou Constructive Solid Geometry, CSG, em inglês). Uma outra maneira de criar modelos 3D é usando uma forma 2D, por exemplo, fazendo a extrusão dela ou revolução da forma 2D no espaço 3D. Para uma introdução nessa técnica, por favor acesse o tutorial irmão Criando uma peça simples com a bancada Part Design. Esses dois tutoriais tem, intencionalmente, o mesmo modelo gerado, para apresentar ao iniciante uma experiência com a mão na massa nas duas diferentes técnicas e como são implementadas no FreeCAD. A definição das duas técnicas pode ser vista como estritamente dividida do ponto de vista semântico, no entanto, não há nada impedindo diretamente uma mistura delas ao criar modelos. Há algumas ressalvas a serem observadas ao misturar técnicas de modelagem, principalmente relacionadas a aspectos de como o FreeCAD é programado. Há um terceiro tutorial, feito como uma primeira introdução a um exemplo de modelagem mista. Esse tutorial utiliza a Bancada Draft para criar um perfil 2D utilizado para extrudar um sólido na Bancada Part para fazer o mesmo modelo deste tutorial.

Antes de começar, dê uma olhada em como navegar no espaço 3D. Ao passar o mouse sobre o seletor de modo do mouse no canto inferior direito da janela do FreeCAD, dicas do modo atual de operação do mouse aparecem como na imagem abaixo.



Muitos novatos em programas CAD travam ao aprender o software. Se isso acontecer com você, por favor, procure mais informações na wiki ou no fórum – é provável que outras pessoas também tenham travado no mesmo ponto, então já pode existir uma resposta para a sua pergunta. Ou faça um post no fórum com suas perguntas ou descobertas. O fórum possui vários tópicos onde os usuários obtém ajuda para concluir todo tipo de tarefa, esses tópicos muitas vezes são semelhantes a tutoriais e frequentemente incluem ilustrações.



O que esse tutorial cobre

 * O modelo a ser criado
 * Usando da Bancada Part para criar e manipular os modelos primitivos
 * Alterando cor e transparência
 * Um modo diferente de posicionar o buraco
 * Tornando o furo um furo escareado (ou rebaixado)
 * Fazendo uma peça oca
 * Uma maneira diferente de posicionar o chanfro
 * Editando dimensões
 * Organizando a árvore ligeiramente diferente
 * Finalizando



O modelo a ser criado






Usando da Bancada Part para criar e manipular os modelos primitivos
Crie um novo documento e salve-o lodo com um novo nome. É uma boa prática garantir que você salve o documento em intervalos regulares ou antes de operações maiores. Em seguida, mude para a Bancada Part usando o seletor de bancadas (rotulado como 10 na imagem vinculada) ou indo para o menu. O FreeCAD iniciará com as barras de ferramentas na parte superior, a 'Tela combinada' à esquerda e a vista 3D à direita.



Crie o bloco sólido principal
Pressione Cubo para criar um cubo sólido padrão. O cubo aparece na Visualização 3D e também um novo objeto na Visualização em árvore na barra lateral.

Pressione Isométrico para ver o cubo em 3D.



Selecione o cubo na Visualização em árvore, ele fica verde na visualização 3D. Abaixo da visualização em árvore você verá agora que o cubo é criado por padrão com as dimensões Length x Width x Height (Comprimento x Largura x Altura) sendo 10 x 10 x 10mm. Mude essas dimensões para 100 x 30 x 50, como no desenho inicial do modelo.



Ao alterar uma propriedade, como Lenght (Comprimento), através da caixa de seleção, você pode inserir os valores ou usar a roda de rolagem para aumentar ou diminuir os valores. As setas para aumentar ou diminuir os valores também podem ser usadas. Na figura mais à direita acima, a propriedade Height (Altura) está em modo de edição, rolando a roda de rolagem quando o mouse está sobre essa célula, o valor será alterado de um em um para cima ou para baixo.

Clique Enquadrar tudo para ver o cubo inteiro.





Criando o arredondamento
Para criar o canto arredondado, na barra de ferramentas, clique em Filete (ou 'Fillet'), o que abre o painel de tarefas para arredondamentos na Tela combinada na lateral. Mude a caixa de seleção do raio para 20 mm e, em seguida, na vista 3D, selecione a borda na lateral superior à direita e clique em.



O painel de tarefas se fecha e você está de volta à visualização em árvore, que agora tem um objeto Fillet ao invés do Cubo anterior.



Visibilidade de filhos
Clique na seta para direita/sinal "maior que" para expandir os filhos do filete, que neste caso é o cubo que criamos anteriormente, mas está esmaecido. Selecione o cubo e pressione a barra de espaço - isso alterna a visibilidade para que o cubo fique visível novamente e o ícone não esteja mais esmaecido. Para desmarcar o cubo, clique em uma área em branco na visualização em árvore ou na visualização 3D.





Crie o chanfro
Em seguida, crie o chanfro de 30 graus, comece alternando a visibilidade do cubo filho do filete. Existe uma ferramenta de chanfro em Bancada Part, mas ao invés de usá-la faremos o chanfro com outro bloco e um corte booleano.

Crie um novo Cubo com dimensões 60 x 30 x 30. Altere o Ângulo de colocação em Placement para -30 graus.



O ângulo de posicionamento está usando o vetor de posicionamento (Eixo) como eixo de rotação. O padrão é o eixo z, que não corresponde à nossa direção desejada. Alterando o vetor de posicionamento para o eixo y produz a orientação necessária da ferramenta de corte para o chanfro.



O mesmo posicionamento também pode ser obtido com outros valores, o exemplo alternativo mais simples de um posicionamento igual é um ângulo de +30 graus e um eixo y de -1.



Console python
Em seguida, a posição precisa ser ajustada. Observando o desenho da peça acabada, não há dimensão direta a ser usada para a translação pretendida para cima. Como a dimensão para cima é a necessária, temos que calculá-la. Vamos usar a Console python embutida para esses cálculos, é trigonometria básica. Se a console Python do FreeCAD não estiver visível para você, basta clicar com o botão direito do mouse em um espaço vazio na área da barra de ferramentas e marcar a Console Python e ela deve aparecer na área de trabalho. Marque também a Tela de relatório se ainda não estiver visível. A tela do relatório na maioria das vezes fornece informações úteis ou até dicas sobre o que fazer a seguir para diferentes comandos.



Depois de importar o módulo math das bibliotecas padrão no python, podemos usar a fórmula (50 - math.tan(math.radians(30)) * 50) para encontrar a distância na direção z que o bloco deve ser movido. Copie o resultado da fórmula da console Python e cole-o na posição z de Cube001. A ferramenta a ser usada para o corte do chanfro agora está orientada e posicionada corretamente.



Expressões
Não é necessário usar a console Python para fazer o cálculo. Na maioria dos casos, ao lidar com valores paramétricos numéricos, o FreeCAD possui um atalho para uma calculadora embutida. Chama-se Expressões no FreeCAD, você pode entrar no modo de expressão clicando primeiro na caixa de seleção para a posição z, um pequeno ícone circular azulado aparecerá no lado direito.



Clicar nesse ícone abre a janela Editor de fórmulas, onde fórmulas e expressões podem ser inseridas conforme mostrado abaixo. Expressões são um recurso poderoso, pois é possível acessar os parâmetros do modelo. Todos os parâmetros do modelo ficam disponíveis como variáveis a serem usadas na criação de uma expressão. Resumindo, em nossa fórmula, ao invés de inserir o número 50 no editor de fórmulas, poderíamos inserir um parâmetro referido contendo o valor 50 do cubo, com a vantagem de que se mudarmos a altura do cubo ', a posição do chanfro seguirá automaticamente. O valor de 50 no modelo atual é referido como Cube.Length, ou seja, a propriedade Length do recurso Cube. Mais informações sobre isso podem ser encontradas no wiki.



Para fazer o corte, com a tecla pressionada primeiro selecione o Fillet na visualização em Árvore e depois o último cubo criado (chamado Cube001) e finalmente na barra de ferramentas pressione o botão  Recortar (Cut). Sua visualização em Árvore agora deve mostrar novamente um único objeto na raiz chamado Cut.



The toolbars
A sidenote on the toolbars, since they are the typical avenue to invoke commands. Although there is a basic setting for the layout of the toolbars, the actual layout on your computer could turn out to be less than ideal. In such cases it is easy to adjust. Consider the upper section of the below image. There are two rows of toolbars and only a limited number of the Part Workbench toolbar buttons are visible. The simplest way to see more toolbar buttons is to maximize the FreeCAD window, unless it already is maximized of course.

More common is to adjust the layout of the toolbars to suit your needs and your specific computer. The repositioning is done with the handle on the left of each toolbar. You can just click and drag the handle to a new location. In the lower section of the below image the toolbar positions have been adjusted, revealing their full content. Changes to toolbar positions are persistent through sessions.



The measurement tool
The measurement tool in the Part Workbench can be used to check that our calculation and placement of the chamfer is correct. Press the Measure Linear button and a task panel opens up, then select the 2 endpoints of one side of the chamfer.



It checks out with an x dimension of 50 mm, clear the measurement and close the dialogue.

Create the hole
To make the hole, press the Cylinder button, set the radius to 5 mm and height to 50 mm.



Next we need to position the hole according to the dimensions in the drawing. Change the view to Top view, then right-click the Cylinder in the Tree view and select Transform from the pop-up menu.



Change the Translation increment to 5 and use the red and green arrow to position the cylinder in the right position, moving it 15 mm in y and 65 in x by dragging the arrow ends with the mouse. Click to close the Transform dialogue. To make the hole press the key and select the Cut and Cylinder in the Tree view, then press the  Cut button in the toolbar. Your Tree view should once again have a single object in the root called Cut001.

Congratulations, the model is now ready.



With the basic model ready, let us explore different ways to alter this model, some examples are related to the appearance, additional features, or simply a different way to do the same.

Changing the color and transparency
There are several different ways one can change the appearance of objects, for this case, let's use the view tab in the property part of the combo view. First select the object in the Tree view and then edit any property like line color, shape color or transparency via the view tab (found at the bottom of the combo view).



Unfortunately when the object is selected it is a bit hard to see how it will look when tuning the new appearance. To see the final result one has to deselect the object. Here is the new look of the model, where one now can see the through hole also in the iso-view. Another way to edit the appearance is via the menu.



A different way to locate the hole
Do a save-as under a new name. Then delete the cut that added the hole and move the cylinder back to zero position. Your model should look like the below picture, which is the starting point for using a different technique to locate the hole at the center of the upper face. Note that the color is back to the default gray, the change in appearance we did was on the cut object which now is deleted.



This time the Draft Workbench will be used to locate the hole. The hole is as before to be located at the center of the upper face, which is the same as the midpoint of the diagonal of the upper face.

Start by switching the workbench to Draft, it might be that a grid appears in the 3D view, the grid visibility can be toggled with Toggle Grid in the toolbar. When making use of the snap functionality in the Draft Workbench it helps to only have the snap types of interest enabled. This time it is sufficient to leave endpoint, midpoint and circle center enabled, so the settings for snapping should look something like below.



Finding the point to place the center of the cylinder could be done by making a diagonal as helpline and use the center of the cylinder and midpoint of the diagonal to identify the points to move between, however it turns out that we do not even need to make any helplines, we can snap on already existing solid geometry.

Select the Cylinder in the Tree view (it turns green in the 3D view) and press the Move button in the toolbar. A task panel opens for moving objects, make sure that Copy is unchecked.



Then move the mouse to the upper face of the cylinder so that you see a white dot in the center of the circle as per the left picture below, this together with the center symbol next to the mouse pointer means that a left button mouse click will snap to the white point.



When you have the white dot on the upper face, click the left mouse button, and repeat for the upper square face of the main solid, like the right picture above, and confirm the choice with a left mouse button click. The snap function makes use of mass-center for any type of face, and in this case the mass center is the same as the geometrical center that is sought after. You will by now have noticed that the move of the cylinder is animated, so you always see what is about to happen.

Repeating the step of the boolean cut from earlier once again will make the through hole that completes the model. Using the linear measurement tool in the Part Workbench, a check that the hole is correctly placed is done. The measurement can only be done between points, so the measurement is done from main body zero to the seam point of the cylinder, meaning that the correct distance is 70 mm instead of the 65 that is on the drawing to account for the extra radius that is included in the distance.



Making the hole a countersunk hole
Switch back to the Part Workbench and create a cone by pressing the Cone button in the toolbar. Change radius1 to 0 mm and radius2 to 7 mm – this will give a 2 mm countersink on the radius. Making the height of the cone 7 mm results in a 90 degree top angle of the cone, or 45 degree countersink angle. Worth to note is that again one could as well use the Chamfer operation.

When working with FreeCAD you will continuously be faced with several different ways to achieve seemingly the same result. There is hardly any absolute truth in what is the right way to achieve a particular end result – however when looking in a specific context one specific workflow can be more flexible, allow for later features to actually be used etc. How you build 3D models will evolve over time as you along the way learn more and more about the features and capabilities of FreeCAD.



Translate the cone so that it is concentric with the hole and coplanar with the main solid upper surface. Use any method described earlier in this tutorial to accomplish that.

In the picture below the move is made with Transform and an increment setting of 1 mm, since the cone has a characteristic dimension of 7 mm, meaning that the earlier increment setting of 5 mm will not allow for correct positioning. The Wireframe rendering is used to easier see that the cone is in the right position.



To complete the model, let's make use of the Boolean command instead of first selecting objects and apply a specific boolean operation. Press the toolbar button and a task panel opens as per the below picture to the left.



Three items needs to be specified, the operation type, the first shape and the second shape. The cone is supposed to be cut, this is called Difference in this command, instead of Cut. The first shape is our Cut001, it is listed under compounds, since it is build from several solids. The second shape is the Cone. Once the correct settings are made for the command, click the button to execute the operation. This has all been done in the picture to the right, and there one can also see that a compound Cut002 is now listed, this is our final model shape. After having changed the appearance the final model looks like this.



Making a hollow piece
Do a save-as under a new name. FreeCAD has all of the typical operations of a 3D modeller, one of them is Thickness, which is used to hollow out parts.

Rotate the view so that the bottom face of the model is visible.



Select the bottom face of the model, then in the Part Workbench select Thickness and the screen should look like below.



Click, as you can see there is now a radius on the hollowed out part.



Moreover, when taking a measurement of the width of the part, it is now 32 mm, so the thickness has been applied outwards. Let’s edit that, double-click the model in the Tree view and modify the join-type settings to intersection and the thickness setting to -1.



Now the outer width of the part is 30 mm, same as before and the corners are all sharp corners.



A different way to position the chamfer
Do a save-as under a new name. Then delete features so that the model looks like below.



Make a Cube with dimensions 30x30x60, ending up like below.



Change the placement by first rotating -120 degrees around the Y-axis.



Finally, change the position to X=50 and Z=50 and make the cut to produce the same result as earlier.



This once again highlights that there are always several ways to produce the same outcome, which is a recurring theme when it comes to 3D modeling. When it comes to basic geometries or solids, one can use different workbenches in FreeCAD as well as different commands and still have the same outer shape of a solid. You simply need to find your own way to a set of preferred tools and workflow that you are comfortable in using. Modeling in parametric 3D is a process of constant learning, and takes practice to master.

Editing dimensions, face colors and TNP
FreeCAD is a parametric 3D modeler, this allows you to change any placement or dimension and the model will update accordingly. In general this works, but it is possible to break a model when edited – for example when a fillet is based on an edge that no longer exists due to editing. When a model breaks during editing, it is referred to as TNP, Topological Naming Problem.

Go ahead and experiment with changing dimensions and placements to see if you can break the model, do not forget to recalculate the model after changes if required. This can be done with the Refresh button in the toolbar, if the icon is grayed out it is not needed to refresh the object.

Reposition the cylinder
Here is an example of the cylinder moved from the center to one side of the main body by using Transform on the cylinder. As can be seen in the picture, the cone is still in the original position, not affected by the move of the cylinder.



When you move the cylinder and break through the outer surface, in version 0.19 you are loosing part of the color settings on your model. FreeCAD reverts to the user default settings for shape colors and transparency in the 3D view, however the Cut002 shape still shows the colors and transparency that it had before as seen in below picture.

Fixing the colors


Here is one way to get it back. First change transparency one tick up or down and then back, that brings back the transparency. You can do the same trick on shape color. Another way to get the color back is to right-click Cut002 in the Tree view and select Set Colors in the context menu. In the task panel that displays, click, that brings back the color to the one set in the view-properties.



The Set Colors command allows you to select individual faces of a shape and set a unique color on the selected faces.

Multiple solids
Another example where the cube that is making the chamfer has been translated and rotated.



As can be seen when repositioning the chamfer in this way, the end result is 3 disjoint solids. Part Workbench allows this, PartDesign Workbench does not, either you will get an multiple solids error or it will simply not render all solids.

TNP
Going back to the original completed model, let’s explore how the faces are named.

Here the selection view has been made active, just to show clearly what is selected and not, also coloring is adjusted so that the selection is easier to see.



Selecting one side face and the cylinder inner face gives that they are internally called face 2 and 9, where face 2 is the side face. Face numbering can be different for you.

Moving the cylinder so that the cavity ends up on the side face, and doing the selection of faces now gives a different number for the cylindrical face.



Face 2 is the right side of the original face 2, the left side of former face 2 is now face 8. The cylindrical part was face 9, but is now face 7. FreeCAD reassigns the numbering and the order is not necessarily preserved. The total face count in the first model is 10, in the version with the cylindrical face piercing the side face, the total face count is 11. So obviously face numbering has to change when the so called topology changes. This probably feels like a minute detail, but turns out to be quite important in parametric 3D CAD. Imagine that you have used the cylindrical face as reference for another feature, it used to be called face 9, but is now called face 8. The reference to the intended cylindrical surface is lost. Since FreeCAD, at least in currently released versions does not keep track of the intended face, it only keeps track of the numbered face, a model breaks when a reference is made to a face that later is renumbered. This is called TNP, Topological Naming Problem.

You are encouraged to learn how to avoid broken models due to TNP, further reading can be done elsewhere on the wiki, which largely focuses on a sketch driven workflow, the underlying mechanism is the same though. The renumbering described here for faces goes for all geometrical entities, faces, edges and vertexes.

Organizing the tree a bit differently
Do a save-as under a new name. Then delete all the cuts ending up with a model looking like below.



When using the Part Workbench and modelling feature rich solids, the tree structure of a solid can become hard to decipher. So far we have created one primitive / feature and applied a boolean operation. In the Part Workbench one can bundle primitives into one boolean operation. In our case we have the cylinder, cone and cube that are all a cut boolean operation.

Instead of making a cut for each primitive, we can first apply a boolean union, Fuse the primitives intended for the boolean cut, and then make the cut between the Fillet and the Fusion.

Using this approach, the Tree view ends up looking like below, which is just a different way of building the same model. Compare this with the original Tree view, none is better than the other, however when making more complex models, one approach over the other can have benefits in ease of modifying/reorganizing the model if needed.



Wrapping up
Having gone through the tutorial you are now briefly acquainted with the user interface of FreeCAD and you have learned the basics in using the Part Workbench. You should now be able to build simple models after your own liking. The Part Workbench is one of the workbenches that can be used to create solids, the PartDesign Workbench is another. The different workbenches have different capabilities and workflows. Learning FreeCAD in full, especially considering all add-ons and macros takes years, so keep on exploring new and different ways of making models – take different tutorials on the wiki, the learning never stops when working with FreeCAD. It is suggested that you learn sketches and the PartDesign Workbench next if your focus is on creating solids. If your focus is modelling buildings your next learning should be the Draft and Arch workbenches.

At last, FreeCAD is made by volunteers in their spare time. If you want to further advance FreeCAD’s capabilities, consider contributing to FreeCAD, for example by improving the documentation.