# How to use Constraints in Creo Parametric Sktetch

Constraints in creo parametric is a set of useful tools when it comes out to make some conditional or restrictive sketching. Although Creo parametric offers constraints during sketching but manual constraint become useful when we have to make some complex geometry for example making turbine blade within creo parametric. There are total nine (9) types of constraints which are listed, with there expected symbols, below:

1) Vertical (symbol “V” )
2) Horizontal (symbol “H” )
3) Perpendicular (symbol can be seen in following figure)
4) Tangent (symbol “T” )
5) Mid-point (Symbol “M” )
6) Parallel (symbol can be seen in following figure)
7) Coincident (symbol can be seen in following figure)
8) Equal (symbol “=” )
9) Symmetric (symbol “–>   <– “)

We will go through each of them one by one.
1) Vertical
First create a random line. Select vertical constraint and then click on the inclined line. This will make it vertical. In figure below line indicating with number “2” will go under this this constraint.
2) Horizontal
Start with construction of line. Select horizontal constraint and then click on the inclined line. This will make it horizontal. In figure below line indicating with number “1” will go under this constraint.

3) Perpendicular
Make two random lines which are not perpendicular to each other as shown in figure below. Now select the perpendicular constrain. After this select the 1st line with labeled “1” and then second line with labeled “2” by clicking on them. This will make them perpendicular.

4) Parallel
Make two lines at any angle but not at right angle to each, i used the same lines those I have shown in previous section, then select the parallel constrain and select the lines one by one.

5) Equal
it simply used to make two entities equal in selected dimensions. Simply draw two random lines or you can use the line which we just made parallel. After this select the equal constraint option and select the lines one by one. Note in right side figure the letter L1 is appearing in after applying constraint.

6) Tangent
To apply tangent constraint you need a curved shape first. For simplicity draw a circle and a line which is not intersecting to the circle. Then select the tangent constraint and select the line and then select the circle. You can impose this constant in reverse order mean first select the circle and then select the line.

7) Mid-Point
First draw a line and draw a point anywhere on the line as shown in fig below (left-side). Now select the midpoint constraint and select the point and then select the corresponding line. This will shift the point from current location to the middle of the line and can be seen in figure below (right side).
Coincident
We will take help from the procedure of mid-point constraint to apply this constraint. After applying midpoint constraint all we need to select the coincident constraint and select the point which we want to make coincide. We will make point coincide with the horizontal line/axis. So after selecting point select the horizontal line this will move the line up to make point coincide with horizontal.
8) Symmetry
This is quit useful constraint and can make 3d CAD modeling easier for you. To apply this constraint we need to draw a center line about which we will make our sketch symmetrical. First make some sketch, for our ease make a rectangle then create a center line. After this select the symmetry option and click the center line and then select the two points on rectangle, which are highlighted, to make them symmetry about the center line.

(update)

Locking The Dimension

if you want to constraint your sketch’s dimensions so it will not change while you drag the sketch. A simple solution to this problem is to “lock ” the dimension. to do this first you have to select the dimension which you want to lock and than “right click” at it. you will see option for lock.

you can Watch the video of the tutorial here.

1. Excellent explanation. Easy to follow for people new to CAD as well as people already familiar with the basic concepts. Thanks for posting

2. After creating sketch how to constraints the sketch using dimensions. for an example creating a rectangle in one plane, in that our rectangle is placed at 1st quadrant.so rectangle left and bottom sides are automatically get geometrically constrained.other sides I gave 100mm and 50mm, after that I drag the sketch it was moving and the dimensions also getting change.how to solve this problem.