How to Make Round Edges in Previous Drawing in Autocad
Circles
To show the Circle tools click the Circle tool drop-down from the Ribbon Home tab > Draw panel.
Command line: To start the Circle tool from the command line, type "C" and press [Enter].
Center, Radius
Specify the location of the centre point then the radius; the radius can either be entered as a numerical value by typing the radius or by clicking a point on the screen. The distance from the centre point to the second point will be used as the radius.
Center, Diameter
The Center, Diameter tool works in the same way as the Center, Radius tool except you are prompted for a diameter instead of a radius.
2-Point
Specify the two points of the circle's diameter.
3-Point
A 3 point circle is a circle that is defined by 3 points. The circle will pass through each of the 3 points.
Tan, Tan, Radius
The Tan, Tan, Radius circle is one which touches two shapes with a specific radius value.
Select the two objects you wish your circle to be tangential to, then specify a radius value.
Tan, Tan, Tan
A Tan, Tan, Tan circle is one which touches 3 shapes.
Select the three objects you wish your circle to be tangential to.
Arcs
From the Ribbon Home tab > Draw panel, click the Arc tool drop-down to show the available arc options. The order displayed on the tool is the order in which you will need to place your points.
Command line: To start the Arc tool from the command line, type "A" and press [Enter].
3-Point
The first point you click is the start of the arc. The second point is the point the arc passes through. The third point the end of the arc.
Start, Center, End
The first point is the start of the arc. The second point is the centre of the arc. The third point is where the arc will end.
Start, Center, Angle
Click the start, then the centre point, then enter an angle value.
Note: The angle is always measured anti-clockwise from the East direction.
Start, Center, Length
Click the start, then the centre point, then type a length for the arc. The length you specify is the "chord length" - that is the distance from point 1 to another point on the circle's circumference. This means the length cannot be greater than the diameter (i.e. 2x the distance between points 1 and 2).
Continue
The Continue tool creates an arc tangential to the last object you drew. To create the arc, click the Endpoint for the new arc.
Note: The remaining arc tools are the same as each of the previously described arcs but the points are placed in a different order.
Placing Polylines
A Polyline is similar to a line except segments are joined to create one object. This makes modifying the Polyline or changing its properties easier, as each segment of the line does not need to be selected individually.
From the Ribbon Home tab > Draw panel, click the Polyline tool.
Command line: To start the Polyline tool from the command line, type "P" and press [Enter].
Click points in the drawing area to specify the points of the Polyline segments.
When selecting one segment of a Polylines, the complete object will be selected.
Polyline Segments
The segment type of a Polyline can be changed from a Line to an Arc. By default the Arc is placed tangential to the last Polyline segment drawn. The Command Line presents the options that allow you to change the Arc type.
From the Ribbon Home tab > Draw panel, click the Polyline tool.
Click your first point to start your Polyline. You will be prompted:
Specify next point or [Arc/Halfwidth/Length/Undo/Width]:
Enter [A] and press [Enter] to change the segment type to Arc.
By default, the next point you click will define the end point of the arc. The arc will be drawn tangential to the last segment.
To change the Arc method, from the command line, enter the capital letter of the Arc point you want to identify.
Specify endpoint of arc or [Angle/CEnter/CLose/Direction/Halfwidth/Line/Radius/Second pt/Undo/Width]:
Angle Allows the angle the arc passes through to be entered.
CEnter Allows the centre point for the arc to be placed.
CLose Joins the end points of the Polyline to the start.
Direction Allows the tangent direction to be entered. The arc will then align tangentially to the end of the previous point and the point you click.
Halfwidth A Polyline can have a thickness; the halfwidth allows specifying half the thickness.
Line Changes the Polyline segment type back to a line.
Radius Allows the radius for the arc to be entered.
Second pt Allows the second point of a 3-point arc to be placed.
Undo Undoes the last segment of Polyline drawn.
Width Similar to the halfwidth option but enters the full width of the Polyline.
Rectangles
The Rectangle tool in AutoCAD creates a closed Polyline in the shape of a square or rectangle.
To create a Rectangle, from the Ribbon Home tab > Draw panel, click the Rectangle button.
Command line: To start the Rectangle tool from the command line, type "REC" and press [Enter].
Specify the first corner point, then the opposite corner point.
Polygons
The Polygon tool creates a Polyline with a determined number of sides of equal length.
To place a Polygon, from the Ribbon Home tab > Draw panel, expand the Rectangle drop-down and click the Polygon tool.
Command line: To start the Polygon tool from the command line, type "POL" and press [Enter].
You are prompted to enter a number of sides. Enter a number between 3 and 1024.
Specify the centre of the polygon. You are then prompted Enter an option [Inscribed in circle/Circumscribed about circle] <I>
Inscribed in circle Creates a polygon where the specified radius is the distance from the centre to one of the vertices of the polygon.
Circumscribed about circle Creates a polygon where the specified radius is the distance from the centre to the midpoint of one the edges of the polygon.
You will finally be prompted Specify radius of circle enter a radius value to create the polygon.
Ellipses
There are two tools for creating ellipses in AutoCAD. There is also a tool to create an elliptical arc.
To place an Ellipse, from the Ribbon Home tab > Draw panel, click the Ellipse tool drop-down to show the available ellipse tools.
Command line: To start the Ellipse tool from the command line, type "EL" and press [Enter].
Center
Specify the centre point, then the endpoint of the first axis followed by the endpoint of the second axis.
Axis, End
Specify the start and endpoints of the first axis, then the endpoint of the second axis.
Source: https://evolve-consultancy.com/product/creating-basic-shapes-in-autocad/