Lesson35- Introduction To Layers



Using layers in AutoCAD is like using overlay drafting or transparencies on an overhead projector.

  • drawing views are a composite of all visible layers.

Why use layers?

Place objects on different layers to control how objects appear on your screen and how they appear in plots.

  • you can assign different color, linetype, lineweight or plot styles to each layer (BYLAYER).

It is easier to manage and edit your drawings later on when objects are placed on separate layers.

You can generate multiple plans from one drawing file by controlling which layers are visible (in plots) on each layout.

Display only the layers you need for the task at hand to make your screen less cluttered and improve your system performance.

Changing the current layer

New objects created by draw commands (e.g. Line) are placed on the current layer.

  • the current layer name is displayed in the layer drop-down list on the Object Properties toolbar.
  • you can select a different layer name from this drop-down list to change the current layer.

You can also use the first Object Properties toolbar button to Make Object’s Layer Current.

  • pick this button then select an object on the layer that you would like to make current.

Changing status of layer settings

You can change status of four layer settings in the Layer drop-down list on the Object Properties toolbar.

  • left-click on the appropriate icon beside the desired layer name in the Layer drop-down list to toggle the status of each setting.

On Off

Use the On & Off setting to control the display of objects on a layer.

  • if a layer is Off you will not see the objects on this layer and they 
will not appear in plots.
  • turn a layer On if you want to see the objects on this layer and if you want these objects to appear in plots.
  • the On/Off status does NOT have an effect on drawing extents.

Frozen Thawed

Use the Frozen & Thawed setting to improve system performance 
by allowing AutoCAD to ignore drawing data on frozen layers.

  • AutoCAD ignores objects on Frozen layers so there are more 
system resources available for objects on Thawed layers.
  • objects on Frozen layers will not appear on your screen and they 
will not appear in plots.
  • the drawing extents is the area occupied by objects on Thawed layers so this setting can affect drawing extents.

Locked Unlocked

Use the Locked & Unlocked setting to protect objects on layers that you do not want to accidentally modify in edit commands.

  • select objects on a Locked layer & AutoCAD tells you how many objects you selected on locked layers but ignores those objects.
  • you can modify objects only if they are on Unlocked layers.

Plot No Plot

Use the Plot & No Plot setting to control whether or not objects will 
appear in plots.

  • objects must be on layers that are On & Thawed before they can appear in a plot.
  • however, even if objects are on layers that are On & Thawed they will not plot if you select No Plot for those layers.
  • for example, set No Plot for your Viewport layers and the border of VIEWPORT objects (on Layouts) will not appear in plots.

Moving objects to a different layer

You can change the layer property of objects by selecting desired objects when no command is running

  • then select the desired layer in the Layer drop-down list of the Object Property toolbar.
  • press <Esc> twice to clear the selected objects & grips after you have moved them to the new layer.

PRACTICE WORKING WITH LAYERS

Step 1:  Launch AutoCAD (if it is not already running). Close all 
open drawings (if there are drawings open).

Step 2: Open the T107_1.dwg drawing in your personal folder.

Step 3: Pick Tools + Run Script. Select your personal folder to Look in and select T107.scr as the script File name. Then pick the Open button to run this script. This sets drafting tools to match the behavior described in the exercises.

Step 4: Left-click on the drop-down arrow in the Layer drop-down list on the Object Properties toolbar. Left-click on the light bulb icon beside Dimensions to toggle this layer Off. Then left-click on the drop-down arrow again to roll up this list.

Step 5:  Pick View + Zoom + Extents.

 

Step 6: Left-click on the drop-down arrow in the Layer drop-down list again. Left-click on the Sun icon beside Dimensions to toggle this layer to the Frozen state & left-click on the drop- down arrow to roll up the list.

Step 7: Pick View + Zoom + Extents again.

You Froze the Dimensions layer so now your drawing extents are smaller.
This time when you Zoomed to the extents you see objects on the other layers at a higher display magnification.

Step 8: Drop-down the Layer list and select Hidden Lines to make this the current layer. The list rolls up automatically.

Step 9: Left-click on the OSNAP status bar button (if it is Off) to turn this drafting tool On.

Step 10: Pick Draw + Circle + Center,Radius. Hold your crosshairs over one of the existing CIRCLEs in the top view to invoke a Center osnap and left-click to use this as the center of the new CIRCLE. The enter 0.32 as the radius.

You changed the current layer from 0 (zero) to Hidden Lines.

  • now any new objects you draw will be placed on the Hidden 
Lines layer automatically.
  • the new CIRCLE uses a blue color and a HIDDEN linetype.

Layer 0 has special properties that you will learn about later on when you work with blocks.

  • you should not use layer 0 as the default layer to place objects.
  • it is better CAD practice to place objects on other layers.

Step 11: Left-click on the first Object Property toolbar button (on left end) and when prompted to select an object click on the LINE near P1.

The Layer drop-down list should show Outline as the current layer.

Step 12: Pick Draw + Circle + Center,Diameter. Hold your crosshairs over one of the existing CIRCLEs in the top view to invoke a Center osnap and left-click to use this as the center of the new CIRCLE. Enter 0.73 as the diameter.

The new CIRLCE uses a white color (black on white background) and uses a continuous linetype because it is on the Outline layer.

Step 13: Drop-down the Layer list and left-click on the lock icon for Outline to Lock this layer. Then roll up the list.

Step 14: Pick Edit + Clear and type ALL at the keyboard when AutoCAD prompts to select objects. Then press <enter> to complete Erase. The command line history is shown.

Command: _erase
Select objects: ALL
61 found
52 were on a locked layer.
were not in current space.
Select objects: ↵
Hatch boundary associativity removed.
Hatch boundary associativity removed.
Command:

You locked the Outline layer so when you tried to Erase objects on this layer (with ALL other objects) these objects were not selected.

  • AutoCAD told you it found 61 objects but 52 objects were on a locked layer so the net number of erased objects was 9.
  • 4 other objects were in another space (on the Clamping Screw layout) so they were not erased either.

Step 15: Left-click on the Clamping Screw Layout to make this the current layout. Double-click outside the sheet near P1 to switch from the MODEL to the PAPER

The VIEWPORT object on this layout was created on the Viewport layer and at the moment this Viewport layer is turned Off.

  • when you are in the MODEL the current VIEWPORT border is highlighted so you can see the edges of this VIEWPORT.
  • this border is not highlighted when you are on the PAPER.

The VIEWPORT border will not be visible if the Viewport layer is Off 
and you are on the PAPER (i.e. not in the MODEL).

  • you normally do not want borders of VIEWPORT objects to appear in plots but it can be practical to see them otherwise.
  • you should leave the Viewport layer On & set the No Plot status for this layer so the borders of VIEWPORT objects will not plot.

Step 16: Right-click on the Clamping Screw layout tab to invoke a shortcut and select Page Setup. Select the Plot Device tab and then select HP LaserJet.pc3 (or equivalent) as the Name for the Plotter configuration. Then select the Layout Settings tab to continue (do NOT pick OK yet).


You must have a plot device selected to see a plot Preview.

  • this drawing was initially saved with None selected as the Name for the Plotter configuration.
  • your instructor may tell to use a different device if your systems are configured for another printer.

Step 17: Verify that Drawing orientation is Portrait then pick OK to complete the changes to your Page Setup.

You will be learning about the other settings for Page Setup later on so do not worry if you do not understand these settings right now.

Step 18: Drop-down the Layer list & notice that the plot status for the Viewport layer is already set to No Plot. Then left-click on the light bulb icon for the Viewport layer to toggle this layer On & then roll up the list.

Step 19: Pick File + Plot Preview & then press <enter>

Step 20: Oops back the Erased objects. Preview the plot with Dimensions Thawed & On. Save your changes.

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