Dynamic blocks have been a part of AutoCAD since release 2006 and have some really nice usages for all disciplines. Unfortunately, it seems that the architectural community that uses AutoCAD has not incorporated dynamic blocks to a very large degree for whatever reasons. An item category that architects specify all the time that are conducive to being a dynamic block are grab bars of varying lengths. I remember having different blocks for each of the different grab bar lengths that I would need on projects. All of those different sizes can be incorporated into one dynamic block.
I’ll go through a step by step process to describe how to create a dynamic block for the grab bar.
Step 1 – Create the basic shape of the grab bar:
This process is just to draw the linework representing the shape of the grab bar. This may already be a block in your library that can be reused. For my illustration, I have drawn the following shape with the origin at the center of the left end.
Step 2 – Create the Block:
Initiate the Block command by either typing the command or selecting Create Block from the Block Definition panel under the Insert tab. In the Block Definition dialog box, type the name “Grab Bar Straight” in the Name box and set the other options as shown in the image below. Pick the Select objects button and select all of the linework that you drew representing the grab bar. Pick the OK button to exit the dialog box and create the basic block.
Step 3 – Create the Length Parameter:
Select the Block Editor command from the Block Definition panel under the Insert tab. In the Edit Block Definition dialog box, select the newly created block named Grab Bar Straight and pick the OK button. The block will open in the Block Editor which only displays that block and nothing else in the drawing.
Go to the Parameter Sets tab of the Block Authoring Palette. (If this palette is not open, go to the Block Edtitor menu tab and select the Authoring Palettes command on the Manage panel.) Select the Linear Stretch tool on the palette.
At the “Specify start point…” prompt, select the center of the left wall mount area of the grab bar. At the “Specify endpoint:” prompt, select the center of the right wall mount area of the grab bar. At the “Specify label location:” prompt, select a point below the grab bar to place the “dimension”. Note that we selected the left end first so that the right end will be what get lengthened when we adjust the size of the grab bar when the grab bar is placed into a drawing.
Step 4 – Specify what gets stretched:
Right-click on the Stretch Action icon (to the lower right of the dimension as shown in image above) and select Action Selection Set -> New Selection Set. At the “Specify first corner of stretch frame:” prompt, pick a point to the upper right of the right end of the grab bar. At the “Specify opposite corner:” prompt, pick a point to the lower left of the right end of the grab bar. (This is done to specify what area will get stretched when the grab bar gets lengthened.) At the “Select objects:” prompt, select all of the linework at the right end of the grab bar, including the 2 long lines that represent the length of the bars. (This is done to tell AutoCAD to perform the stretch command on the selected linework when the grab bar gets lengthened.) Press Enter to finish selecting linework that will get stretched.
Step 5 – Establish Allowable Lengths of Grab Bar:
Highlight the Distance1 “dimension” parameter, right-click and select Properties. In the Properties palette, go to the bottom of the palette in the Value Set section and change the Dist Type option to “List“.
In the Value Set section, pick the button (with 3 dots) to the right of the Dist Value List option. In the Add Distance Value dialog box, enter the allowable lengths for the grab bar (with a comma separator) then pick the Add button. Pick the OK button to exit the dialog box.
Step 6 – Rename Parameter Name (Optional):
In the Property Labels section of the Properties dialog box, change the Distance name option to something other than “Distance1“. Changing this name to “Grab Bar Length” or other name will make it easier to understand precisely what the distance parameter is for. When the dynamic block is highlighted in a drawing, this parameter name will be displayed under the Custom category of the Properties palette. This does not change the functionality of the dynamic block.
Step 7 – Save the Changes:
Pick the Close Block Editor button at the top right of the screen. Select the “Save the changes to Grab Bar Straight” option in the closing dialog box that will appear.
When this grab bar dynamic block is placed in the drawing, the user can select the right end of the block and move the arrow to one of the preset lengths. The allowable lengths appear as temporary lines as shown in the illustration below.
I hope that this encourages you to look for more applications for dynamic blocks.