Add Coincident

Toolbar-ConstraintCoincident

Toolbar:

Constraints toolbar

Menu:

Add menu > Geometry sub-menu> > Constraints sub-menu > Add Coincident

To add:

Click Add Coincident Constraint, then click:

•two Lines (or: a Line and the X-axis or Y–axis)

- or -

•a Point and a Line (or a Circle), (or a Point and the X-axis or Y–axis)

- or -

•two Points

- or -

•or a Point and a Motion-Point

To delete:
1.Click a sketch-element that is 'coincident' with a different sketch-element...

The sketch-element and the constraint show in the Selection-Window.

- or -

1.In the Geometry Tree, explore the 'Constraint Loops' to find the Coincident constraint
2.Click the Coincident constraint.

The Coincident constraint is now in the Selection-Window.

2.Right-click the Coincident constraint in the Selection-Window
3.Click 'Delete' in the contextual-menu

Result:

If the two sketch-elements have a total of more than two degrees-of-freedom:

•the two Lines (or a Line and the X or Y–axis) become collinear

- or -

•the Point becomes coincident with the 'ray' of the Line,
•the Point becomes coincident with the circumference of the Circle

- or -

•the two Points become coincident.

Note: If the two sketch-elements have a total of 1 degree-of-freedom, then the two sketch-elements cannot become 'coincident'.

In MechDesigner, you cannot remove more than two degrees-of-freedom from a Point. For example, you cannot do these two steps:

STEP 1: Add a Coincident Constraint between a Point and a Line (or axis) - this removes 1 degree-of-freedom from the Point.
STEP 2: Add a Coincident Constraint between the same Point and another Point - this attempts to remove a further 2 degrees-of-freedom - it CANNOT!

Why:

•A Coincident Constraint between a Point and a Line removes 1 DOF from the Point.
•A Coincident Constraint between a Point and a Point removes 2 DOF from the Point.

Thus, delete the constraint between the Point and the Line (STEP 1), before you add the constraint between the two Points (STEP 2).

About Point Symbols

•'+' : centre-Points - at the centre of Arcs and Circles
•'O' : start-Point or end-Point - at the end of a Line and Arc
• CirclePlus : centre-Point that is coincident with a start-Point or end-Point.

You may need to select the '+' or the 'O' with a command, and it is important to see the difference between the two Points and be able to select one Point or the other Point.

When a centre-Point is Merged with a start-Point or end-Point of a Line or Arc, the symbol is a '+'. You cannot select one or the other, because there is only one Point.

•Motion-Point : Motion-Point - added to a sketch-element with Add Motion-Path FB.
•Motion-Point Point: Motion-Point coincident with a start-Point or end-Point.

See Also:

Merge-Points, Horizontal, Vertical

All About Sketch-Loops

Notes:

Use Add Coincident between two Points for construction geometry.

Use Merge-Points for sketch-loops and sketch-paths.

Points that are 'coincident' give you the option to delete the Coincident Constraint later.

Coincident constraints in the Graphic-Area, Selection-Window and Geometry-Tree.

Before

After

Select:

In Selection-Window &

Geometry-Tree as...

Geometry-coin-lines - b4

Geometry-coin-lines - af
•Two Lines:
•Line and X or Y–axis

The Lines become collinear

CoincidentLtoLn

geometry-coin-ptol b41

geometry-coin-ptol af1
•Point and Line (or X & Y–axis)
a.The Point lies on 'ray' of the Line.

CoincidentPtoLn

MD-CoincidentLinetoPL-b4

MD-CoincidentLinetoPL
b.A Point in a sketch-element and Line

MD-coincidentLinetoAxisb4

MD-coincidentLinetoAxisaf
c.The X or Y–axis or Ray of the X or Y–axis.

Geometry-coin-ptoc b4

Geometry-coin-ptoc af
•Point and Circle:

The Point is constrained to lie on the circumference of a Circle

CoincidentPtoCn

geometry-coin-ptop b41

geometry-coin-ptop af1
•Point and Point:

The Points become coincident

CoincidentPtoPn

 

Tutorial and Reference Help Files for MechDesigner and MotionDesigner 13.2 + © Machine, Mechanism, Motion and Cam Design Software by PSMotion Ltd