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Isnin, 18 Januari 2016

AutoCAD dimension text

The annotation part of a project is one if not the most important part of a CAD project, since printing a Dimensionless drawing will basically make your project unusable.
It is almost always the case to have the dimension style disproportional to the scale of the project you are working on, making it necessary to know how to tweak the Dimension-text scale and often the other parameters like the offset distance of the text from the dimension lines, the scale of the arrowheads and others.

AUTOCAD DIMENSION TEXT

To change the parameters of you Dimensions, You can use the command line: DIMSTYLE.
dimension-autocad
If you type DIMSTYLE and Press ENTER you will have the immediate access to the Dimension Style Manager shown below
dimension-autocad
You can decide to create a completely new Style, or just to Modify the default one. We will focus on few modifications you can make and how each influences the drawing.
Talking about having invisible text on your dimension, On the Text Tab,you can change the height, the text style, the text color and more.
If your text is too big or too small compared to the dimensions of yourdrawings, you might want to tweak its height for it to fit appropriately in your project.
dimension-autocad
Most time, you will also want to change the Offset from dim line, which is how far the dimension will be from the dim line.
dimension-autocad
On the first image above, you can notice how inappropriate the text is, increasing the value of the offset from the dim line allow to push the text upward as shown on the second image.

SYMBOLS AND ARROWS

The Symbols and Arrows tab looks as on the image below
dimension-autocad
You can play with the style of the arrowheads, and their size.
dimension-autocad
This tab gives the control over the size of the arrowheads as well.
dimension-autocad

LINE

This tab could also be a lot helpful.
dimension-autocad
Here you can change the extension lines offset from the origin.
dimension-autocad

PRECISION

This tab allows to set the precision of the value of your dimensions, you can decide to have only one decimal digit,  more or no decimal digit at all. You can also round off your dimensions.
For those who would also like to change the decimal separator, you can do this too.
dimension-autocad
Of course there are way more options than what we have described in this post. feel free to explore them, change them and see how they affect the dimensions on your project.
Some industry have a standard of how much dimensions should weight relatively to the overall scale of the project, you might want to check them out to be sure about how good to set yours.
HOW TO DRAW A SPRING
Here we will be using the SWEEP command, just as the EXTRUDE command we have made use of when we built out first figure in AutoCAD, it helps obtain cylinders from circles and can do more.
The SWEEP command works with few differences similarly to the EXTRUDE command. It helps obtain 3D object from 2D object, just by indicating the path through which the 2D object is going to SWEEP to create the 3D object.
An easy example to demonstrate the possibilities of the SWEEP command is to build a 3D spring in AutoCAD using the SWEEP command and the HELIX command.
Going from the objects in Image 1 to Image 2.


sweep-AutoCAD
sweep-AutoCAD
Let’s use this opportunity to learn how to create an Helix in AutoCAD.
Create an helix in AutoCAD
  1. Type HELIX and press ENTER
  2. Specify the center point of the base
  3. Specify the value of the base radius
  4. Specify the value of the top radius
  5. Specify the height of the helix.
It is to be mentioned that there are many options you can make use of while using the HELIX command. Using this command  you can build an helix based on the number of turns of the helix and/or the height-difference between two subsequent turns.
Here are few things you can build using the HELIX command
sweep-AutoCAD
(a) Spiral
(b) Base radius smaller than top radius (spring)
(c) Base radius bigger than top radius (spring)
(d) uniform spring

 SWEEP IN AUTOCAD

Let’s come back to the main topic of this post, which is the use of the SWEEP command in AutoCAD.
We have had a fun exercise using the 3DROTATE lately, we are right going to use the product of it to build the following 3D object in AutoCAD.
Using images on the left and the SWEEP command, we can build the image on the right.
sweep-AutoCAD

FINAL OBJECT

sweep-AutoCAD
How do you actually use the SWEEP command in AutoCAD.
  1. Type SWEEP and press ENTER
  2. Select object to sweep and press ENTER
  3. Select SWEEP path
As simple as that.
To build the image above

STEP 1

We have 12 segments that will serve as SWEEP path (Use this post to learn how to get this object built)
3drotate-AutoCAD

STEP 2

What we need now, is to draw a circle, duplicate it so to have 12 of them in total.

STEP 3

Sweep 12 times, using each time a circle as the object to sweep and asegment as a sweep path.

3D SPRING

Coming back to our HELICES and let’s SWEEP them with objects having different shapes.
sweep-AutoCAD
(a) Object to SWEEP: circle
(b) Object to SWEEP: Ellipse
(c) Object to SWEEP: Rectangle
(d) Object to SWEEP: Triangle
The resulting image
sweep-AutoCAD
Additional images
sweep-AutoCAD