Free contour

To place an inner contour on the front panel via a DXF import, select the ‘Insert free contour’ function on the menu bar. In the subsequent ‘Free contour properties’ dialogue box, you can specify all the required properties.

The free contour can be executed as a cut-out or as a cavity.

If you have made subsequent changes to the DXF file, they can be applied immediately using the ‘Update‘ button.

Detailed step-by-step instructions for the DXF import of outer and inner contours are provided here as a manual in PDF format.

A free contour is a freely designable closed line, along which the milling cutter travels either as an outer or an inner contour:

•	For milling objects that are positioned on the main plate, the continuous line shows an inner contour on the main plate, for which a single area ("cutout") is cut out or vacated.

•	If the outline of the mainplate is designed as a free contour, the line represents the outer contour of the main plate.

In principle you can save as many closed lines as you like in one file. These can be inserted as free contour objects, which using the option Selection > split free contour (see further down on this page) can be broken up into a corresponding number of objects, each represented by a single closed line.

DXF-files can be imported both in the Insert > Free contour dialog box as well as in the File > Front panel properties dialog box and then remain available for the duration of the session both for the design of the main plate outline as well as for the insertion of milling elements with free contours respectively.

Use the multiselection option in the import dialog box (hold downCtrl key and click the desired DXF files one after another) to open multiple files.

When you close the front panel file however, only the DXF files of the objects actually placed are stored, which will be displayed from the start when you next edit the front panel.

Each of these DXF files can contain any number of closed lines (outlines), which neither cross each other nor themselves, as well as precisely one cross of short lines (e.g. 5 mm in length) as an application-specific reference point (details below under "Specification of the free contour vector graphic for the milling element").

The handling of these features depends on whether the file is used as a Main plate outline or as a milling element:

Feature	Main plate outline	Milling element
Multitude of closed lines	Only the first closed line listed is taken into account.	All of the closed lines listed are taken into account or milled.
	-	A milling element which contains several free contours, may be subsequently split (see the appropriate section below).
	The selected line is treated as the outer contour.	All other lines are treated as inner contours.
Two short intersecting lines	Their presence is ignored, as the reference point of the main plate (also the origin or origin of coordinates) is automatically derived from the resulting geometry of the main plate.	Their intersection can be determined as a reference point for the milling element in its properties dialog box.

At present, free contour vector graphics for both the outline of the main plate as well as for a milling element can only be imported in DXF file format.

On the DXF file format The Drawing Interchange Format (DXF) is a CAD file format for the AutoCAD program developed by Autodesk for the exchange of digital design data. A DXF file describes a CAD model (e.g. a drawing) as a collection of vectors, described in writing according to the ASCII standard. The documentation of the file format is freely accessible. As a vector graphics format, the import of DXF is possible in many graphics programs in a similar way to the plotter language HPGL.

The following requirements must be satisfied for a vector graphic, so that it can be used to represent a milling element or create the basic shape of a main plate:

•	The vector graphic may contain an infinite number of closed lines. Note: In favor of a main plate outline, the first closed line listed is selected.

•	Every closed line can be made up of vectorially representable elements which show two endpoints, for example of straight lines and arcs.

•	Every endpoint of an element must be exactly connected with the endpoint of another element (Note: minimum tolerances are allowed for the connection, as endpoints that are snapped together by some programs are not stored as completely accurately overlapping).

•	The file may only contain closed lines which do not intersect each other.

•	Each closed line may only enclose a single area, meaning that it may not intersect itself. (Accordingly a closed eight is not permitted, for example.)

•	The file may contain exactly one pair of short, intersecting lines (of 5 mm for example). This point of intersection may, where necessary, be selected as a reference point of the resulting free contour milling element.

Vector graphics which do not meet these requirements will not be imported and therefore cannot be used. If an import attempt fails, a graphically supported error list is generated.

Error message	Explanation
Contour not closed	A line has been discovered which, also taking a tolerance for detecting snapped endpoints into account, can be interpreted as not closed.
Double line	Elements which completely or partially cover each other have been discovered in a closed line. Note: This is to prevent the price being unnecessarily increased through the associated additional tool movements.
Multiple origins	More than one origin has been found.
Overlapping	Either a closed line has been discovered that intersects itself, or two closed lines have been discovered which overlap each other.
(Blank display)	The DXF file either contains no closed lines or this is not a DXF file.

The user can also generate the reference point for his free contour as the junction of two additional short, mutually intersecting line segments (of, for example, 5 mm in length).

The presence of such a feature is checked during import and, if necessary, is offered as an option for the reference point of the object in the properties dialog box. For further options, see the entry "Reference point" under the following heading "Free contour properties".

After placing the object you can set the following variables for the required free contour in the properties dialog box:

Variable	Description
DXF file	Select the desired DXF file from the suggestion list or import it from its location. At the bottom of the preview the size of the object to be placed will be shown subject to its "scaling" (see below).
Reference point	You can optionally select as a point of reference either a) between 5 points of the rectangular outline of the object, b) the origin of the DXF file, or c) the optional reference point generated by the user by adding a cross (see above).
Angle of rotation	Rotation angle of the free contour around its reference point.
Scaling	Adaptation of the original absolute values given in the DXF file for the dimensions in %.
Tool	With the tool you can in particular optimize the cutting out of small inner radii and narrow openings as well as, for example, triangles with narrow aperture angles.
Mirror	Option of mirroring the free contour on its vertical axis through the reference point.
Cavity …	Option of placing the free contour as a cavity with adjustable depth (in this case, there is only one machinable edge, see next line), where required also on the reverse side
Do not produce object	If you do not want to produce a free contour, but to place it on the front panel for information purposes only - for example as a marker - then check this box.
Edge machining >>>	The option of producing one or both edges of the free contour with either a bevel or with a rounding (details).

Milling elements which contain several closed lines are automatically split immediately after they are imported and then grouped in order to keep them together. If necessary, however, the group can be split up, after which the individual elements can be edited as required, added to new groups or combined to form macro objects.

If individual elements cannot be produced using the initially selected tools, for example, because the contour is too small, an automatic tool adjustment is made. The user is notified of this should this be the case.

Every line can be individually assigned to a tool.

Tip: Every free contour element that is split can be selected directly by pressing Ctrl + left mouse button without breaking up the group.

Due to the finite diameter of a milling tool, intended and achievable free contours – especially with small internal radii or narrow aperture angles - do not match in all circumstances. Differences can be discerned in the preview window in that the original contour is shown as a red dashed line in addition to the free contour that can actually be produced. This allows you to readily see that certain contours, for example, are completely ignored if they are too small or the tool is too large.

Alternatively, differences can be discerned, e.g., typing Ctrl + d to toggle between full and outline mode .

The choice of a smaller diameter for the tool will always lead to a better approximation at the positions in question. Please note that additional costs are incurred for a tool change as well as for longer milling times (when using a smaller tool diameter).

For certain necessary features - for example, a corner with an inner radius of zero - you can continue to work with an additional drilled hole or for right angles also by placing a rectangle. These additional milling elements are then each placed before the free contour is milled.

In individual cases, when Front Panel Designer is updated, a free contour that was loaded with an older version of program is produced differently owing to error corrections made in Front Panel Designer.

The user will be notified in such cases when the file is loaded.

The presentation of the free contour is saved to the FPD file and is typically not recalculated. In the case described above, you can enforce this by selecting View → Clear DXF Preview in the menu.