CAM offset (milling path)
Purpose
The CAM offset shifts a whole contour of lines, arcs, circles, ellipses, elliptical arcs, polylines, splines or rectangles by a distance — the way a cutter path runs around a workpiece: outer corners optionally get radii (the cutter radius), inner corners are intersected. Unlike the simple Offset the tool follows the contour from element to element automatically and creates a connected path — of lines and arcs, a circle for a full round, and on request with splines at the smooth places (Result).
The distance comes from the window CAM-Offset, live from the mouse or from a measurement of two points in the drawing.
Access
- Ribbon: group Modify, triangle on the button Offset — CAM offset (2).
- Classic toolbar: drop-down triangle of the family Offset (4).
- Command search : CAM-Offset.
In the English interface the command carries the German name CAM-Offset (Fräsbahn) in the command search, and the window title reads CAM-Offset; the instruction bar shows only the identifier camoffset in both languages (program version v3.0.31).
Procedure
- Start the tool — the window CAM-Offset opens, the status line reports CAM offset: click an element · mouse = side and distance · ESC = cancel.
- Click a contour element (1). The program follows the contour over the shared endpoints in both directions until it is closed or ends; the chosen elements are highlighted, the status line counts: CAM offset: 6 elements selected (closed) · create in the dialog or right-click · ESC = cancel.
- Move the mouse (2): the pointer's side determines whether the path runs outside or inside, the distance to the element the offset — the preview follows live, the field Distance in the window shows the value.
- Create: button Create in the window or right-click. The status line confirms CAM offset: 8 element(s) created, distance 12.00.
Esc cancels at any time (CAM offset cancelled), closes the window and switches to Select — even while the preview is hanging at the mouse.
Setting the distance
Three ways, each overriding the previous one:
- Mouse — as long as the preview runs live, the distance follows the pointer.
- Field Distance — type a value; the typed value takes precedence over the mouse and pauses the live preview. A click into empty space (next to the contour) pauses the live preview and puts the current distance highlighted into the field (CAM offset: preview paused — overwrite the value or create · double-click the field = live again). A double-click into the field hands the lead back to the mouse.
- Measure 📏 — CAM offset measure: click the first point, then click the second point: the distance of the two points is adopted (CAM offset: distance 12.50 measured).
Junctions and manual selection
If several elements meet at an endpoint, the tracking stops: CAM offset: junction — click the continuation (2 options). You click the element with which the contour should continue. Clicking an already chosen element again removes it from the chain.
With the checkbox Select geometry manually the program follows nothing automatically: every clicked element joins the chain, a second click removes it again — the way for contours with gaps or overlaps. Contour elements are lines, arcs, circles, ellipses and elliptical arcs, polylines, splines and rectangles; texts, dimensions, hatches and block instances do not belong (CAM offset: no contour element at the click point (line/arc/circle/ellipse/polyline/spline/rectangle)).
Circles, ellipses and splines — the result
A closed element is a contour in itself: a circle or a closed ellipse becomes a path with a single click, chaining it with other elements is not possible (CAM offset: closed elements cannot be chained). Open curves — elliptical arcs and splines — join the chain over their endpoints just like lines and arcs.
The parallel curve of an ellipse or a spline is neither an ellipse nor a circular arc itself. The program therefore computes it exactly and stores it in one of two forms:
| Check box Smooth curves as spline | Result |
|---|---|
| off (factory) | The whole path consists of lines and arcs; the shifted curves become fine polylines. The offset is accurate to fractions of a hundredth of a millimetre. |
| on | Every connected smooth run becomes one spline — the path stays smooth at the curves and consists of few objects. At corners and where the inner offset clips the curve, lines are still created. |
The offset of a full circle is always a circle again — regardless of the check box.
The program remembers the choice for the next call. It is in the window CAM-Offset and can still be switched after the contour has been chosen; the preview follows immediately.
For the simple Offset of a single element the same choice is available through a toggle button in the floating value field — there with the additional option of replacing the parallel curve of an ellipse by an approximated ellipse.
Options and relations
- Radii at outer corners (default on): outer corners are travelled with arcs of the radius of the distance — the path of a cutter. Without the checkbox the shifted lines meet sharply.
- If the offset is too large for the contour — e.g. inwards in a narrow pocket — no path is created (CAM offset: no valid path — the offset is too large for this contour).
- The path is created on the active layer as individual objects — lines, arcs, a circle for a full round, with the check box also splines; it is one step for Undo.
- The tracking uses the shared endpoints of the elements; you get gapless contours with the object snap when drawing or afterwards with Weld.
- The last used distance and the check box Smooth curves as spline are in the window again at the next call.
Related commands
- Window CAM-Offset — all fields
- Offset — parallel to a single element
- Weld