Free contour

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A basic free contour is a closed outline you draw yourself, made of straight sides and arcs, on one of the four long faces. Everything inside the outline is milled out, down to a depth or right through the part. It follows the BTLx FreeContour processing.

Depth 10 mm

Depth 20 mm

Depth 40 mm

Free contour. Drawn by the editor's own geometry code; right: the carved part in 3D.

When to use it

Use it for a shape no other processing makes: a slot with round ends, a dovetail socket, an L-shaped housing, a rounded recess for a fitting. When the shape is a plain rectangle, a mortise or a notch says the same thing in a form more machines accept.

Fields

Veld	Eenheid	Bereik of opties	Standaard	Wat het verandert
Position X	mm	from 0	1460	Where the outline starts along the part.
Position Y	mm		40	Where the outline starts across the face, measured the way the machine file measures it.
Face		Top, Bottom, Front, Back	Top	The side of the part the processing is on.
Rotation	°	-180 to 180	0	Turns the whole outline in the face.
Through			off	Cut right through to the opposite face.
Depth	mm	from 0	20	How deep the outline is milled.

Default: what Add fills in on a 3000 mm part of 120 x 120 mm.

The outline itself is a list of corners, measured from X and Y. Each corner has a Rise: how far the side to the next corner bows away from a straight line, in millimetres. 0 is straight. A positive rise bows outwards, a negative one inwards, and the rise can be at most half the side, which makes a semicircle.

Open paths and machining planes

For BTL, the contour controls also offer open paths, a separate clearing choice, saw/milling/pen/planing types, tool position, wall inclinations and corresponding upper/lower outlines. A custom reference plane translates and turns the path in the selected side. Keep associated outlines’ point counts and segment types equal. P05 limits machining depth; the lower outline defines the wall direction.

These extended forms keep their exact lines and arcs in BTL. Their tool width and curved display are nominal in the preview. BTLx, BVN and BVX report these extended forms as machining losses. Additional machining explains reference planes and receiver checks.

Add a free contour

Select the part in the Parts list.
Under Extra processings, click Add.
Type contour in the search field and pick Free contour. It starts as a slot with round ends on the top face.
Open its card. Under Shape, pick a ready-made outline: rectangle, rounded rectangle, slot, circle, dovetail or L-shape. The shape keeps the size the outline already has.
Change the corners in the list, or add and remove corners with the buttons beside each one.
Set Face, Position X, Position Y, Depth or Through.
Check that the part shows a green check. If not, open the Issues tab.

Draw it or import it

For a shape of your own, draw it on the face with the pen, curvature, rectangle and circle tools, or import an SVG file. Both are on their own page: Draw a contour.

Sharp corners

A milling cutter is round, so it cannot cut a sharp corner on the inside of a recess. The app assumes a 20 mm cutter and warns about every corner the cutter cannot reach, and about every curve tighter than the cutter’s radius. The machine still cuts the contour, but leaves the cutter’s radius in those corners and follows those curves wider. If your shop uses another size, set it once per project under Mill diameter, in the Model section of the fitting workspace’s World panel.

The warning offers two fixes, both in one click:

Round them gives each corner the cutter’s radius (10 mm for a 20 mm cutter), also where a side is an arc or a curve. The recess then has exactly the shape the machine cuts.
Dog bones mills a little past each corner, so a square part still seats fully. Use it for a housing that has to take a square tenon.

Corners on the edge of the face, where the cutter runs off the timber, are never flagged. A curve that is too tight has no one-click fix: reshape it in the drawing.

Machine export

Format	Status	Details
BTLx	Partly supported	FreeContour: a closed outline of lines and arcs with straight walls, cut to a depth or right through. A round hole or a box square to the beam goes out as Drilling, Mortise or Lap.
BVN (Hundegger)	Partly supported	When the contour is exactly a round hole up to 100 mm (0400), a box inside the face (0502), a box open to its edge (0300) or a rectangle turned in the face (0305). A rectangle through the part and a band at an angle across the whole face go out as a through housing and the angled band, with a note in the file. Otherwise it goes out built from housings (0300, 0305) and holes (0400) that together cut exactly the outline, such as an L, a T, a cross, dog bones or a keyhole; a turned housing only where the relief BVN mills in its corners stays in the outline. A contour cut right through the part that is none of these goes out as the machine's free milling path (operations 3000 to 3005), which CAMBIUM turned into its own contour, with a note in the file. A contour that stops at a depth and is none of these is listed as a machining loss, with the reason.
BVX2 (Hundegger)	Partly supported	When the contour is exactly a round hole up to 100 mm, a box inside the face, a box open to its edge or a rectangle turned in the face (a turned Pocket), it goes out as that operation. Otherwise it goes out built from Pockets, laps and Drillings that together cut exactly the outline, such as an L, a T, a cross, dog bones or a keyhole, turned too. Any other outline, a rectangle through the part and a band at an angle across the whole face included, goes out as CAMBIUM's own OutlinedBody. That is not yet confirmed on a machine; the export notes this without blocking. In the shop test pack the through rectangle and the angled band go out as a through Pocket and an angled lap instead. CAMBIUM's OutlinedBody is read back as a free contour on import.
BTL 10.6	Supported	250 open or closed contours, arcs, inclined walls, associated rims and rigid reference planes. Tool-selected envelopes have caveats.

BTL status describes what the specification can represent. CAMBIUM imported our earlier BTL test files; confirmation applies to the tested forms and build. See BTL coverage for representation and receiver caveats.

When the contour is exactly a round hole (up to 100 mm across) or a box square to the beam, it is written as a drilling, a mortise or a notch in every format that supports that processing. Nothing is rounded to get there; a box a hair out of square stays a contour.

BVN and BVX also take a rectangle turned in the face, written as the turned housing CAMBIUM has read, and a rectangle cut right through the part and a band across the whole face at an angle (the shape of an angled half-lap), which CAMBIUM read as meant in the shop’s September test. The file notes that these are not yet confirmed on a machine.

Any other shape goes to BTLx as a free contour, and to BTL as its free contour record (250): a start record and one record for each side, straight or arced. CAMBIUM reads our BTL files, but has not shown this record yet, so the file notes that. BVX and BVN get it built from housings, notches and holes the machine already cuts, when together they cut exactly your outline, never half of it. That works for an L, T, U, cross, stepped or notched outline, square or turned in the face, for dog-boned corners and for a round lobe on a side. In Fitting, a designed joint that goes out this way is kept in BVX and BVN mode. In BVN, the shapes that can’t be built this way are listed as a machining loss, with the reason:

sides at more than two angles, like a triangle, a V or a dovetail;
a round end or a rounded corner, where the cutter (Mill diameter under World → Model) would leave a thin strip of wood between a housing and a hole;
a turned shape whose pieces meet inside it, where the relief BVN mills in each corner of a turned housing would cut into wood the outline keeps.

BVX writes every other shape as CAMBIUM’s own outline element, OutlinedBody: the whole outline, lines and arcs, to a depth or right through. CAMBIUM has not yet confirmed how it reads one, so the file carries a note to check the part during machine setup. It does not block the export.

A contour cut right through the part goes to BVN as the machine’s free milling path (operations 3000 to 3005): the whole outline, lines and arcs, whatever its shape. CAMBIUM turned such a path from our test file into its own contour, so the file carries a note to check it during machine setup, without blocking the export. The path runs round the inside of the outline, with the cutter inside the shape you cut out. A contour that stops at a depth has no such path in BVN: for those, send BVX or BTL.

Which file for a free contour

Your contour	BVN	BVX	BTL
A hole, a box or a turned box	yes	yes	yes
Built from housings and holes (an L, a T, a keyhole)	yes	yes	yes, as a contour
Any other shape, right through	yes, with a note	yes, with a note	yes, with a note
Any other shape, to a depth	lost	yes, with a note	yes, with a note

A free outline in a BVX file from CAMBIUM comes in as a free contour you can see and edit, with a note that CAMBIUM has not confirmed that reading yet. Left unchanged, it goes back to BVX just as it came.