The purpose of grids is to allow efficient placement, movement and connection between symbols and wires.
Kicad 7 grid features can be found in the upper section of the Icon list on the Left of the workspace, in View > Grid Properties and in Preferences > Symbol & Schematic Editors > Display Properties & Colors.
Kicad 8 grid features can be found in the upper section of the Icon list on the left of the workspace and in Preferences > Symbol & Schematic Editors > Display Properties & Grid & Colors.
Most grid functions are designed for personal preference. These are self explanatory or may be understood with a little experimentation.
One exception is the distance between grid lines, in both the horizontal and vertical planes. This is generally called “The Grid” and serves as an extremely important function in these Editors and should only be altered with great care.
The Kicad Library Convention places all pins for all symbols in the Kicad Libraries on a 50mil (1.27mm) Grid. Consequently, for correct results in the Schematic Editor, placement and movement of symbols and their connecting wires must be carried out with this grid setting. This grid setting must also be used for pin placement in the Symbol editor to allow created and altered symbols to conform with other elements used in the Schematic Editor.
Remember: The default Grid setting is 50 mil (1.27 mm).
Reference to this grid setting in both Editors can always be found to the right center, under the work sheet.
It is a worthwhile procedure to check this setting when opening and; periodically, when using both these Editors.
There are two main reasons a user may find themselves “off grid” in these Editors.
- The user has forgotten to return to the 50mil grid after using a different grid setting for: eg. Text placement in the Schematic Editor or graphics placement in the Symbol Editor.
- The user has accidentally hit a hotkey that has changed the grid. The “N” hotkey will change the grid setting (refer to Hotkeys in Preferences) The “N” key is very easy to strike if miss-keying the “M” (move) hotkey.
When the user finds that some, or all elements, have strayed “off grid”, the quickest and easiest procedure to correct the drawing is to:
- Reset the grid to 50 mil (1.27 mm).
- Create a Selection Box around the entire content of the schematic drawing
- Right Mouse Click somewhere inside that Selection Box.
- From the newly opened Selection List, Left Mouse Click “Align Elements to Grid”.
A very convenient method to avoid changing “The Grid” when fine adjustments are needed, not necessarily requiring a grid, is to use the “Ctrl” key.
When the Ctrl key is held down, the movement of the mouse is no longer restricted to the Grid. This can be of great benefit when moving items such as text.
Footnote:
The author, to overcome the "N’ key problem has simply changed two hotkeys from their default.
- Switch to Previous Grid remains “Shift + N”.
- Switch to Next Grid is now “Alt + N” from “N”.
- Grid Properties is now “N”.