Spirals (Sketch)

Sketch > Draw > Freehand > Spirals

Procedure:

To create individual spirals, proceed as follows.

Specify the start points of the centre axis. If you want to align the spiral to the current processing plane, right-click instead of determining a point. In this case, continue with point 4.
Specify the end point of the end point of the centre axis. Alternatively, you can also press the ESC key, and specify the direction of the centre axis. To do this, select the appropriate functions of the vector menu. The functions of the menu correspond to that of the Move, points/edges/surface menus. Then continue with point 4.
Define the start point of the spiral.
The Generate spiral window is displayed.

On the various tabs of the dialogue window you can specify the parameters for spiral generation. Click the Preview button to see how the current settings will influence the appearance of the spiral.

Confirm your settings with OK.

The Generate spiral dialogue window

Dimensions
In this tab, you define the dimensions of the spiral. These are:

the Height
the Angle
the Start diameter and
the End diameter

Please note that these values influence each other mutually.

Click the or button to activate the Distance or Angle menu and apply the corresponding value from the drawing.

Beneath Position you can click the or button to change the centre axis or the start point of the spiral.

Form
In this tab, you specify the form of the spiral. To do this, you can enter the number of Windings (integral or real), the End angle as well as the Start and the End for the Lead. Please note that these values influence each other mutually. In addition, you can invert both the direction and the rotation direction of the spiral.

Options
Spirals can be represented as
a Spline,
a Polyline or
a Compound curve.

Moreover, you can influencethe representation accuracy of the spiral: In the Specify accuracy field, select Number of points per full cycle or Tolerance. You can only specify a tolerance for compound curves!

Ends
Here, you define whether you want the ends to be flat and, if so, at what transition angle - separately for the Start and End of the spiral.

The total height of the spiral is 1/2 * number of revolutions * (Lead at the Start + Lead at the End).

Example 1:

Dimensions		Form		Type		Ends
Height	100	Turns:	4	Spline		Start	flat
Diameter, Start	30	End angle:	0	Tolerance	0.01	End	flat
Diameter, End	50	Lead, Start:	25
Angle	autom.	Lead, End:	25

Spiral in side view, top view and axonometric view

Example 2:

Dimensions		Form		Type		Ends
Height	100	Turns:	4	Spline		Start	flat
Angle	45	End angle:	0	Tolerance	0.01	End	flat
Diameter, Start	30.	Lead, Start:	25			Angle	45 °
Diameter, End	auto.	Lead, End:	25
		Rotation direction, inv.

Spiral in side view, top view and axonometric view