Урок по черчению

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Руководство
Тема
Черчение
Уровень
Начинающий
Время для завершения
30 минут
Авторы
Drei и vocx
FreeCAD версия
0.19
Примеры файлов
Draft tutorial updated
Смотрите также
None

Введение

Этот учебник был сначала написан Drei, и был переписан и иллюстрирован vocx.

Данный урок знакомит пользователя с основами рабочего процесса Верстака Draft.

Читатель будет практиковаться в:

  • создании линий, дуг и полигонов
  • использование рабочих поверхностей
  • создание размеров, текста и надписей
  • создание технических чертежей

В уроке используется нотация (x, y, z) для указания координат точки объекта. Размеры по умолчанию в миллиметрах mm.

Final drawing including various Draft objects.

Установка

1. Open FreeCAD, create a new empty document with File → New.

1.1. Switch to the Draft Workbench from the workbench selector, or the menu View → Workbench → Draft.
1.2. Make sure you understand how to use the property editor, particularly the Data and View tabs to change the properties.
1.3. Since the Draft objects are planar shapes, they are better viewed from the top. Use View top to set the 3D view.
1.4. Although it is not used in this tutorial, the Draft grid is helpful to position geometrical elements. Use SelectPlane to set both the working plane and the grid, and then show and hide the grid with Toggle grid.

Панель инструментов привязки

2. The Draft Snap toolbar is normally activated when you switch to the Draft Workbench.

2.1. To make sure it is always there, go to the Draft Preferences, Edit → Preferences → Draft → Grid and snapping tab.
2.2. Verify that the Show Draft Snap toolbar is active.

Вы так же можете изменить в этом окне видимость и параметры сетки Draft.

Working planes

Most Draft objects are planar shapes so they are naturally based on a working plane. A working plane can be one of the main XY, XZ, and YZ global coordinate planes, or it can be a plane that is parallel to them with a positive or negative offset, or it can be a plane defined by the face of a solid object.

3. Press SelectPlane, or go to the menu Utilities → Select plane, to open the working plane task panel.

3.1. Press Top (XY).

Before pressing the button, you can also change the value of the offset in millimeters, as well as the grid spacing, the main lines and snapping radius.

Линии и дуги

4. Мы создадим дуги и линии.

4.1. Нажмите Arc.
4.2. Установите Center в(0, 0, 0), и нажмите Enter.
4.3. Установите Radius в 30 mm, и нажмите Enter.
4.4. Установите Start angle в 60.0°, и нажмите Enter.
4.5. Установите Aperture angle to 60.0°, и нажмите Enter.
4.6. Повторите эту процедуру для следующей дуги с радиусом 25 mm, остальные параметры те же

5. Теперь создадим замкнутый профиль, связав дуги с линиями.

5.1. Нажмите Line.
5.2. В Snap toolbar убедитесь, что File:Draft ToggleSnap.svg режим привязки активен, с одним только Endpoint вдобавок. Когда Вы придвините указатель к конечной точке дуги, появится иконка Endpoint. Кликните для выбора этой точки.
5.3. Переместите указатель к ближайшей конечной точке другой дуги, чтобы связать две дуги вместе.
5.4. Повторите процесс для другой стороны дуги, чтобы закрыть профиль.

Closed profile created by two arcs and two lines.

Fusing or compounding

Теперь в древе проекта есть несколько объектов, которые образуют закрытый профиль. Однако этот профиль все еще состоит из отключенных объектов; каждый из них может быть отредактирован и перемещен независимо от других. Возможно продолжить работу с отдельными элементами как они есть, но в данном случае мы объединим их в один объект.

6а. Обратите внимание, что объединение объектов в один объект приведет к созданию объекта, который больше не является параметрическим, поэтому их свойства не могут быть изменены в дальнейшем.

6a.1. Выберите все четыре объекта в древе проекта, или, удерживая Ctrl, выберите их в трёхмерном виде.
6a.2. Выбрав эти объекты, нажмите Upgrade.
6a.3. Это обновит четыре объекта в один Wire.

6b. If you wish to maintain the parametric nature of the objects you can create a compound instead.

6b.1. Switch to the Part Workbench.
6b.2. With these objects selected, click on Part Compound.

Rectangles, circles, and polygons

7. We will draw a rectangular frame.

7.1. Press Rectangle.
7.2. Enter the values of the first point (-100, -60, 0), and press Enter.
7.3. Make sure the Relative option is unchecked, as we will use absolute units. You may press R in the keyboard to quickly toggle this option on and off.
7.4. Enter the values for the second point (140, 90, 0), and press Enter.

A rectangle is created. Go in the property editor to change its properties. If you don't want the rectangle to create a face, set ДанныеMake Face to false. If you want to make a face, but see only the wires of that object, keep ДанныеMake Face to true but set the ВидDisplay Mode to Wireframe.

8. Нарисуем круг.

8.1. Нажмите Circle.
8.2. Введите значения центра (0, 0, 0) и нажмите Enter.
8.3. Установите радиус 15 mm и нажмите Enter.

9. Нарисуем правильный многоугольник.

9.1. Нажмите Polygon.
9.2. Введите значения центра (0, 0, 0) и нажмите Enter.
9.3. Установите количество сторон 6 и нажмите Enter.
9.4. Установите радиус 50 мм и нажмите Enter.

Again, you may change the ДанныеMake Face and ВидDisplay Mode properties in the property editor if you want.

The rectangle, the circle, the polygon, and most other objects created with the Draft Workbench share many data and view properties because they are derived from the same base class, Part Part2DObject.

Rectangle, circle and polygon added.

Arrays

Arrays are used to replicate an object several times in an orthogonal direction (X, Y, Z), around a revolution axis, or along a path.

10. We will create a polar array.

10.1. Select the Wire object that was previously created with the Upgrade tool, or the Compound created with the Part Compound tool.
10.2. Press PolarArray.
10.3. Adjust the polar angle to 360°.
10.4. Set the number of elements to 4.
10.5. Enter the values for the center of rotation (0, 0, 0), and press Enter.

Old workflow

10.2. Press Array.
10.3. Go to the tree view, select the Array object, and then go to the property editor, and change the ДанныеArray Type from ortho to polar.
10.4. Change ДанныеNumber Polar to 4, and ДанныеAngle to 360°.

The array object shows copies of the object around the origin.

Polar array of the small profile centered around the origin.

Dimensions

Linear dimensions work best when using the appropriate Draft Snap methods to select points and edges to measure. However, they can also be created by specifying absolute coordinates.

11. Create dimensions for the different objects.

11.1. Press Dimension.
11.2. Pick the first point. In this tutorial the first point will always be the origin (0, 0, 0).
11.3. In the Snap toolbar make sure File:Draft ToggleSnap.svg Toggle snap is active, and only Midpoint as well. As you move the pointer to the top edge of the polygon, the Midpoint icon should appear; click to select this point.
11.4. Move the cursor to the right to specify the location of the dimension, then click to set the final position, around (100, 20, 0). The dimension will automatically show the length value measured between the two points.
11.5. Select the dimension object in the tree view, and in the property editor, change ВидFont Size to 6 mm, set ВидExt Lines to 45 mm, and ВидShow Unit to false.

12. Повторите процесс для двух дуг замкнутого профиля. Первая точка измерения по-прежнему будет в исходной, а вторая точка будет использовать среднюю точку дуги.

13. Repeat the process for the circle located in the center. The first point of the measurement will still be the origin. To select the second point make sure File:Draft ToggleSnap.svg Toggle snap is active, and only Angle as well. As you move the pointer to the top of the circle, the Angle icon should appear; click to select this point. Then move the cursor to the right, and click to fix the dimension.

Remember to adjust the ВидFont Size, and other properties to see the dimension correctly.

Dimensions that measure the vertical distance from the origin to the top of the circle, arcs, and polygon.

Texts and ShapeStrings

14. Text objects are simple planar figures that are created in the 3D view but don't have an actual "shape" underneath. This means that they cannot be used in complex operations with shapes like extrusions or boolean operations.

14.1. Press Text.
14.2. Select the reference point in the 3D view. In the Snap toolbar make sure File:Draft ToggleSnap.svg Toggle snap is active, and only Midpoint as well. Move the pointer to the top edge of the highest arc, so that the Midpoint icon appears; click to select this point.
14.3. Enter the desired Text, and press Enter once to start a new line; add more lines of text as needed.
14.4. When you are ready to finish with edition, press Enter twice.
14.5. Select the text object in the tree view, and in the property editor, change ВидFont Size to 6 mm, and ВидJustification to Center.

15. ShapeString objects are shapes made of primitive wires that follow the lines indicated by a certain font. This means that these objects have a real "shape" underneath, and thus can be used in complex operations like extrusions and boolean operations.

15.1. Press ShapeString.
15.2. Move the pointer to the desired location in the 3D view above the regular polygon, and click once. This will fix the base point for the ShapeString. The coordinates may be entered manually as well, for example, (-20, 65, 0).
15.3. Enter the desired String, and choose the desired Height.
15.4. If there is no default font file, you must click on the ellipsis ... to open a dialog window to choose the font location in the system.
15.5. When a valid font file has been specified, you may proceed to click OK or press Enter.

Text and ShapeString objects added.

To extrude letters and engrave them on to solids, see the Draft ShapeString tutorial.

Creating technical drawings

As it is now, the objects that we have created can be saved, exported to other formats like SVG or DXF, or printed.

If you wish, you may create a technical drawing to display these objects together with additional information like a frame.

Before doing anything, hide the Draft grid by pressing Toggle grid.

16. Switch to the TechDraw Workbench.

16.1. Create a standard page by pressing TechDraw PageDefault.
16.2. In the tree view select all objects created, except for the Page, and then press TechDraw ActiveView. Press OK with the default options; it may take a few seconds to create the view in the page.
16.3. Selecting the Page object in the tree view will automatically display the Page in the main window. With the Page selected, go to the property editor, and change ДанныеScale to 0.75.
16.4. Expand the Page object in the tree view to select the ActiveView object. With this view selected, go to the property editor, and change ДанныеScale Type to Page.
16.5. Recompute the model by using Refresh or pressing F5.
16.6. Hide the frames of the objects by pressing TechDraw ToggleFrame.

Learn more about the TechDraw Workbench by reading the Basic TechDraw Tutorial.

TechDraw page with a projection of the shapes created with the Draft Workbench.

TechDraw works best with objects that have a Part TopoShape. Since some objects from Draft, like Draft Texts and Draft Dimensions, don't have such "shapes", some operations of TechDraw don't work with these elements.

Tools like TechDraw ActiveView, TechDraw DraftView, and TechDraw ArchView work by receiving an internal SVG image that is generated by internal Draft functions; therefore, TechDraw doesn't have much control about how these views are displayed. More integration of Draft and TechDraw is a work in progress.

Конечные замечания

The Draft Workbench in many ways is similar to the Sketcher Workbench, as both are intended to produce 2D shapes. The main difference is in the way each workbench handles coordinate systems, and how the objects are positioned. In Draft, objects are freely positioned in the global coordinates system, usually snapping their points to a grid, or to other objects. In Sketcher, a "sketch object" defines a local coordinate system which serves as the reference for all geometrical elements within that sketch. Moreover, the sketch relies on "constraints" to define the final position of its points.

  • The Sketcher Workbench is intended for 2D drawings that require precise relationships between its points. It does not rely on a grid, but on rules of positioning (constraints) to determine where the points and edges will be placed. The Sketcher Workbench is mostly used together with the PartDesign Workbench for the creation of solid bodies.

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