Sketch Constraints
This tutorial provides a visual guide to the behavior of various constraints. Although the constraint icons and keyboard shortcuts are for Onshape, the selection logic and their behaviors are generally applicable to all CAD software (with a handful of exceptions).
Coincident (i)
The coincident constraint is used to make points touch other entities. The available modes are:
Two points - the points become touching.
Applying coincident to points
A point and a line, circle or arc - the point becomes inline with the path of the line, circle, or arc.
Applying coincident to a point and a line or circle
Note
This mode treats arcs as circles and lines as infinite, so points are not required to lie within the physical limits of the edge.
Two lines - the lines become inline with each other.
Applying coincident to lines
Vertical (v)
The vertical constraint is used to make either lines or pairs of points vertical relative to the sketch plane. The available modes are:
Line - the line becomes vertical.
Applying vertical to a line
Two points - the points become vertically inline with each other.
Applying vertical to two points
Horizontal (h)
The horizontal constraint is used to make either lines or pairs of points horizontal relative to the sketch plane. The available modes are:
Line - the line becomes horizontal.
Applying horizontal to a line
Two points - the points become horizontally inline with each other.
Applying horizontal to two points
Parallel (b)
The parallel constraint is used to make lines parallel to each other, meaning they point in the same direction. The available mode is:
Two lines - the lines become parallel.
Applying parallel to two lines
Note
Parallel makes lines share the same direction, but it does not force them to be inline with each other.
To make two lines inline, use coincident with two lines.
Perpendicular (Shift + l)
The perpendicular constraint is used to make lines perpendicular to each other, meaning they are at right angles relative to each other. The available mode is:
Two lines - the lines become perpendicular to each other.
Applying perpendicular to two lines
Equal (e)
The equal constraint is used to constrain the lengths of lines or the radius of arcs/circles to be the same. The available modes are:
Two lines - the length of each line becomes the same.
Applying equal to lines
Two circles or arcs - the radius of each circle or arc becomes the same.
Applying equal to circles and arcs
Tip
Equal can be applied to multiple entities at once by preselecting them before clicking .
Midpoint (Shift + m)
The midpoint constraint is used constrain points to lie along the center of a line or between two other points. The available modes are:
A point and a line - the point is placed in the middle of the line.
Applying midpoint to points and lines
Three points - the middle point is centered between the other two points.
Applying midpoint to points
Tip
The order of selection does not matter, only the relative position of the points prior to midpoint being added.
Tangent (t)
The tangent constraint is used to make lines tangent to a circle or arc. A line is tangent when its edge touches the circle at a single point. The available modes are:
A line and a circle or arc - the line becomes tangent to the circle or arc.
Applying tangent to lines and a circle
Two circles or arcs - The circles or arcs become tangent to one another.
Applying tangent to circles and arcs
Concentric (Shift + o)
The concentric constraint makes circular entities share the same center point. The available modes are:
Two circles or arcs - the centers of the circles or arcs become coincident.
Applying concentric to circles and arcs
A point and a circle or arc - the point becomes coincident to the center of the circle or arc.
Applying concentric to a points