Dimensioning

A dimension Dimension shows a measure of the drawing: a length, a distance, a diameter, a radius, an angle or an arc length. You do not type the number — the program measures the geometry and writes the value at the dimension line. When the geometry changes, the dimension follows. Dimensions are objects of their own beside geometry, hatches and text: they have a Z level, their own system layer Dimensions, a set of display attributes (font, arrows, unit, decimal places) and a reference to the dimensioned points or elements.

This page describes the connections. The step-by-step instructions are under How-to, the commands under Dimension, Arc length dimension, Angle from 3 points, Chain dimension, Baseline dimension, Datum feature, Feature control frame, Dimensions to back and Dimension settings, the dialogs under Dimension Settings, Edit dimension and Feature control frame, the messages under Dimensioning messages.

Dimension types#

LiberoDraft distinguishes two families of dimensions. Element dimensions are attached to an element: to a line (linear dimension), a circle (diameter), an arc (radius or arc length), a rectangle (width and height) or a polyline segment. They are created when you click the element itself with the dimension tool. Point-to-point dimensions connect two snapped points; they are created when you click two points with point snap (endpoint, midpoint, centre, intersection, tangent). In addition there are the dimensions between two elements: the angle between two lines, the distance between two parallel lines and the perpendicular distance from a line to a point.

Which type a point-to-point dimension becomes is decided by the position of the pointer at the third click relative to the rectangle spanned by the two points: inside the rectangle you get the aligned dimension (the direct distance), left or right of it the vertical, above or below it the horizontal dimension. If both points are at the same height only the horizontal dimension is possible; at the same width only the vertical one. The status bar reads Position the dimension line (H/V automatic)…, and the preview shows the result before you click.

Anatomy of a dimension#

The dimension line (1) runs parallel to the measured distance; its offset from the geometry is free and can be changed later by dragging. The extension lines (2) lead from the reference points to the dimension line and protrude beyond it by the Extension line overshoot (5) (factory 1 mm). The dimension text (3) sits centred above the dimension line but can be moved along it. The arrowheads (4) point at the extension lines; if the distance is too short for arrows and text, the arrows flip outside, or you set Arrows: Outside in the attribute panel.

All sizes are real millimetres of the drawing: text height (factory 3.5 mm), arrow length (3.5 mm), arrow width (1.2 mm), overshoot (1 mm). On screen they grow and shrink with the zoom; on paper at scale 1:1 they are exactly this size. So that arrows do not vanish at small zoom, a minimum size of 9 pixels applies on screen; it never inflates the arrows beyond a quarter of the dimension line.

Driven, driving, detached#

Every dimension has one of three modes. You choose it in the Edit dimension dialog with the three buttons ⟳ driven, 🔒 driving and ✂ detached.

• Driven (factory setting): The dimension measures the geometry. The value is locked; when the geometry changes, the number changes. A driven dimension is a reference dimension. With Driven dimensions in parentheses in the Dimension Settings it appears as (40) — but only for dimension types that could be driving.
• Driving: The entered value forces the geometry to this size. For a line the length is set — the end that is connected via welds to a fixed element is held; if no end is clearly rigid, the midpoint stays. For an angular dimension the first chosen line keeps its direction, the second is rotated about the intersection. Driving dimensions also act in the constraint solver: if the geometry is moved or distorted, the program re-enforces the driving values. A fixed element Fixed can never be driven; the driving button is then disabled.
• Detached: The dimension text is free text — or empty, then only the dimension line remains. The geometry stays unchanged, tolerances are dropped. When switching, the current displayed value is preset as text.

Linear, radius, diameter, rectangle, polyline segment and angular dimensions over two lines can be driving. Point-to-point dimensions, parallel distances, arc length dimensions, angles from three points and all dimensions that measure model geometry through a viewport are always driven.

Tracking and binding#

An element dimension knows its element; if the line is lengthened or the circle enlarged, the text is right at once. A point-to-point dimension remembers, for each point, the element and the point index where it was snapped — the nearest point of all elements counts, not the first within tolerance, so the binding does not jump between close neighbouring points. When the point moves, the dimension moves with it. A point without snap stays free.

In the Select tool a selected point-to-point dimension shows small squares at both reference points: filled for a free point, hollow for a bound one. Drag a square to reposition the point with the current snap (Reposition dimension point (with snap) — release to place); the old binding is released and a new one is sought at the target. On a radius dimension the square sits at the arrow tip on the arc; use it to move the arrow along the arc.

If a dimensioned element is deleted, its element dimension disappears with it. When moving, copying, rotating and mirroring, the dimensions whose references lie completely within the selection travel along; explicitly selected dimensions always travel. Cut and paste via the clipboard behave the same (dimensions and hatches travel with their elements).

Moving and selecting dimensions#

In the Select tool you grab a dimension at its dimension line or at its text:

• Dragging the dimension line changes the offset from the geometry (for point-to-point dimensions the position of the dimension line). A label at the pointer shows the value. When grabbed, the line stays exactly where it is; it does not jump to the pointer.
• Dragging the dimension text moves it along the dimension line. With Snap dimensions (smart guides) the text snaps to the middle and dimension lines align with existing dimensions (alignment line). Holding Ctrl suppresses snapping temporarily. Since program version v3.0.47 the same alignment works already while placing (alignment snap) — there, however, without a suppression key.
• A click selects the dimension; Shift-click adds further dimensions to the selection. Del deletes the selected dimensions.
• Double-click opens Edit dimension; Ctrl+double-click opens the attribute panel. Both are also in the right-click menu.
• PgUp and PgDn raise or lower the Z level of the selected dimensions.

Dimensions in a locked group cannot be selected; dimensions belonging to a group are hidden with it. If an element is on a hidden layer, the dimension attached to it disappears as well.

Chain and baseline dimensions#

Chain dimension Chain dimension and baseline dimension Baseline dimension are series modes of the dimension tool. The first dimension is created like a normal point-to-point dimension with a position click; its style (horizontal, vertical or oblique) and the position of the dimension line apply to the whole series. Every further dimension needs only one click per point; the status bar counts (Dimension 2 placed — click next point, ESC finishes). Esc or a tool change ends the series (Dimension series finished).

• In a chain dimension every further dimension starts at the endpoint of the previous one. All members of a chain form one unit: move one and the whole chain follows; move a shared point and the neighbour moves along. After each click the program orders the points along the chain axis and rebuilds the members as a gapless partition — even a click back (say 0, 15, 21, 38, then 36) produces no overlapping segments. Two points at the same axis position count as one. The chain stays oriented at the first clicked point.
• With Chain: running total from zero point (factory on) the running total from the first point appears at every extension line, rotated by 90°; 0 stands at the zero point. The totals can be dragged with the mouse; a sideways offset produces a kink in the extension line.
• Right-click on a chain member offers Insert chain dimension…: a click inside a member splits it at the snapped point, a click outside the chain extends it to the new point. Right-click Dissolve dim. chain or Explode turns the members into ordinary individual dimensions.
• If the first dimension is oblique (aligned), it fixes the orientation angle; the chain is kept as a rotated dimension, and points beside the axis are projected onto it.

• In a baseline dimension every further dimension starts at the base point (the first point); the dimension lines are staggered outwards. The stagger is 2.5 times the text height (factory 8.75 mm).

Under Recent commands in the right-click menu the function actually used appears (Chain dimensioning, Baseline dimensioning) instead of the general entry Dimension.

Settings and dimension styles#

The Dimension Settings dialog defines the defaults for new dimensions: font, text height, colour, line width, arrow style and size, overshoot, decimal places, unit, arrow type, chain running totals. The basic rule:

A dimension style is a named set of all these values. Three factory styles (★) are part of the delivery: Maschinenbau (mm) (mechanical engineering, arrows), Holzbau (mm) (timber construction, 45° slashes), Baubemassung (m/cm) (building dimensioning with slashes, larger overshoot and the m/cm unit). You save your own styles with Save as…; they live in the browser of this computer and are available in all drawings. Factory styles can neither be overwritten nor deleted — change the values and save under your own name. If a loaded drawing carries a style that does not exist on this computer, it appears as a provisional entry ⟨from the drawing⟩ … and disappears again as soon as another style is active.

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★ Save as default stores all values of the dialog together with the chosen style permanently: they apply at the next program start and travel via Save/load settings to another computer as well.

Units#

Drawing is always done in millimetres; the unit only affects the display. mm shows the number without suffix, cm and m convert and append the unit. m/cm (Bau) follows building dimensioning: from 1 m in metres with two decimal places (= cm), below that in centimetres; half a centimetre appears as a superscript digit — 845 mm become 84⁵, 2365 mm become 2.36⁵. Full metres appear without the cm digits when Hide trailing zeros is on (2.00 → 2). The unit is stored per dimension; in the attribute panel it can be changed for individual dimensions.

Decimal places and zeros#

Linear dimensions and angular dimensions have separate settings for decimal places and Hide trailing zeros (40.00 → 40, 40.50 → 40.5). In the Edit dimension dialog, Decimals overrides the default for a single dimension; Default restores it.

Dimension text and tolerances#

The Edit dimension dialog adds a prefix (such as ⌀, R, M or 2x), a suffix (such as H7) and a tolerance to the dimension text; the text can be underlined per DIN (not to scale). Five tolerance kinds are available:

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For class + deviations and limit dimensions the ⚙ determine button derives the deviations from the tolerance class and the nominal size; the values come from the freely extensible file toleranzen.json in the program folder (capital letters = hole, lower-case letters = shaft). If the value of a driving dimension changes afterwards, the program updates determined deviations at the next redraw; hand-typed deviations stay. Angular dimensions have no classes (ISO 286 applies to lengths).

Radius and diameter dimensions can be converted into each other in the same dialog with R ⟷ ⌀; Arrow: inside/outside sets the arrowhead, and for a radius outside hides the line to the centre. For linear dimensions ↤ Side 1 and Side 2 ↦ hide arrowhead and extension line per side — for dimensions ending at a centre line or a break.

Live dimensions while drawing#

With Create dimensions while drawing (factory on, in the Settings dialog ) every drawn element gets a dimension at once: a line its linear dimension, a rectangle width and height, a circle the diameter, an arc the radius, a polyline one dimension per segment. The offset of these dimensions from the geometry is the Dimension offset while drawing of the Dimension Settings (factory 10 mm). The preview of the dimension already appears while drawing; for selected, not yet dimensioned elements the program additionally shows a pale auxiliary dimension. If the option is off, no dimensions are created while drawing and the auxiliary dimensions are dropped; the dimension tool itself always shows its preview.

Dimensions in viewports#

In the paper space you can dimension model geometry through a viewport: the snap reaches the model points through the viewport, and a point-to-point dimension whose two points came through the same viewport shows the world value — the measured paper distance is multiplied by the viewport scale. Circles, arcs and lines in the viewport can also be dimensioned as elements. Such through dimensions follow the model geometry; if the viewport scale changes, the value stays right. They are always driven because the geometry lies in model space and must not be driven from the sheet. If the viewport is deleted, the dimension loses its reference.

Dimensions in blocks and groups#

When a block is created, the explicitly selected dimensions and all dimensions whose references lie completely within the selection move into the block definition; when the block is exploded they come back (Restored from blocks: n dimensions). Elements inside a block can be dimensioned from outside without exploding the block. Dimensions in a group are hidden and locked with it. Context of the blocks: Blocks. The item balloon Balloon belongs to the dimension family: it hangs on a block instance and shows its item number from the parts list; it takes text and arrow size from the dimension settings.

Z level, layer, visibility#

Every dimension lies on a Z level; new dimensions take the current drawing Z level. Dimensions to back Send to back puts all dimensions, feature control frames and datum features on the lowest occupied Z level so that they hide nothing. The system layer Dimensions in the layer panel hides and shows all dimensions, feature control frames, datum features and balloons together; dimensions on hidden Z levels or with only invisible reference elements are not drawn. In addition, every new dimension carries a drawing layer — the layer from the field Layer name of the box Dimension layer in the Settings dialog if it exists in the drawing (factory Mass), otherwise the active layer; eye and lock of the layer act on the dimension, and the layer can be changed in the Properties panel. A group may also consist of dimensions only.

Print, SVG and DXF#

When printing Print, the row ◇ Dimensions: under Line widths (mm) sets the print width of dimension lines and extension lines (factory 0.2 mm; per ISO/DIN both are equally thick). Arrow length and text height come from the Dimension Settings and are exactly the set size on paper at scale 1:1.

In DXF dimensions travel exploded: dimension lines, extension lines, arrows and text form one block per dimension so that the dimension can be grabbed in one piece in the target CAD. A real DIMENSION object would not be an image of the drawing because the target CAD would redraw it in its own style. The description of the dimension travels inside the block; LiberoDraft rebuilds a real dimension from it when reading back. Conversely LiberoDraft imports DXF dimensions of the types linear, aligned, diameter, radius and three-point angle as dimensions, provided the associated geometry is found.

Feature control frames and datum features#

Geometrical tolerances per DIN EN ISO 1101 belong to dimensioning: the datum feature Datum feature attaches a box with the letter A, B, C … to an element, the feature control frame Feature control frame carries characteristic, tolerance zone, value, modifier and up to three datums in up to three rows. Both are bound to the element and move with it; their text height follows the text height of the dimensioning.

Known limits#

• Polylines, splines, ellipses and points cannot be dimensioned as elements; the remedy is point snap or Explode.
• Point-to-point dimensions, parallel distances, arc length dimensions, angles from three points and through dimensions cannot be driving.
• The angular dimension needs two non-parallel lines; angles between arcs or against polyline segments are not possible.
• Your own dimension styles live in the browser of the computer; the drawing carries only the name of the active style, the values are stored in every dimension.
• The ⚙ determine button finds only classes that are entered in toleranzen.json; if an entry is missing, a message appears.