SNAP & GRID

Today let’s study the bottommost horizontal bar at center that is meant for Drafting Setting.

Before getting into these TABS let us understand that AutoCAD works on the philosophy of Co-ordinate Systems. Being a vector-based application every entity in AutoCAD is a Vector – an object with Dimension and Direction. To achieve this it is imperative to LOCATE the points forming that object or geometry. There are different means of locating the points in a space or drawing, most common and popular being the coordination.

In AutoCAD every point or location is referred in terms of X, Y and Z coordinates. As we already know Origin is a point in the space with 0, 0, 0 values for X, Y and Z respectively. X is the displacement of a particular point in horizontal direction from the origin, Y is the displacement of that point in vertical direction from the origin and Z is the displacement of it in the direction perpendicular to the XY plane. Z is also referred as the Elevation or Level for this reason. Any point that is elevated from XY plane in the upward direction has a positive nonzero Z value and if it is dropped down from XY plane it is supposed to have some negative nonzero Z value.

Alright, now as we have understood the concept of XY Plane, Origin and Coordinates, let’s move on to learn the first TWO tabs of Drafting Setting namely SNAP and GRID.

There are some basic assumptions for using SNAP and GRID.

1. SNAP and GRID should always be used in unison as only one of them would be ineffective.
2. GRID is a matrix of DOTS forming a square or rectangle depending upon the limits set.
3. Limits – the user specified area in the space – and GRID are relative. This means that if you set limits to a high value, say 12000, 9000 and try to set the GRID with value 1, it could not be displayed as it would become too dense and AutoCAD will warn you about the same.
4. SNAP and GRID work only in X and Y direction. By this what I mean is it is impossible to set the SNAP and GRID in a triangular, circular or any other fashion, for that matter, other than linear.
5. Although AutoCAD by default forms a square GRID with identical X and Y values, it is possible to set different X and Y values for GRID as well as SNAP, provided they blong to the same table. You can not set GRID 5, 5 and SNAP 3, 3.

Okay, now let’s try to practice it by applying Limits, turning ON the GRID and SNAP.
Follow the steps below to complete the exercise in the picture.

1. From the Format menu select the 'Drawing Limits' and turn them ON by entering values 0, 0 for the Lower Left Corner and 6000, 5400 for the Upper Right Corner.
2. From the View menu select 'Zoom – All' to ‘Apply’ the limits.
3. Right Click on the SNAP or GRID button and select Settings
4. In the Drafting Settings dialogue box put the values as shown - In the Grid, enter 150 in X spacing and 150 in Y spacing fields. In Snap, enter 300 in X spacing and 150 in Y spacing fields.
5. Check the boxes against Snap On (F9) and Grid On (F7) to turn ON Snap and Grid.
6. Type ‘L’ at the command prompt to initiate the Line command.
7. Specify 300,300 as the start point.
8. To draw the first step, move the mouse upward and click at the first point where it locks. Move the mouse rightward and click at the first point where it locks.
9. Repeat step 8 for 17 times to draw 17 more steps.
10. Move the mouse downwards and click to form the closure.
11. Move the mouse diagonally downwards till it is in line with the start point and below top of the first step and click to form the waist of the stair.
12. Type ‘C’ and enter to close and finish your staircase.

Congratulations! You have just completed the First Assignment with AutoCAD!
Tomorrow we will explore the Saving Options and analyze our First Assignment.

Stay Tuned…!