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CAD Intermediate – What is UCS for Anyway?

What is a UCS for? UCS Stands for User Coordinate System. Basically it means you can define your coordinate system for the requirements of your drawing. I can’t tell you how many times people have come to me and asked “how do I get my drawing to rotate correctly?” Yes that is a pretty loaded question. Truth is there are a variety of answers. A UCS can be used to provide better means of editing certain components in your model. It can be used for getting your border to rotate like you want it, a UCS can be used to show different views. A UCS can be used to translate from one coordinate system to another coordinate system. There are a number of applications to utilize a UCS. Do you have to completely understand what’s going on, No, but you will work better if you do.

What is a coordinate system? I believe most of us learned in School the Cartesian coordinate system in math. X and Y axis system and some even expanded into Z for 3D points. AutoCAD uses the same thing. I’m pretty sure you knew that, but trying to establish some history and base reference. The coordinate system is relative to where you associate 0,0,0. The World Coordinate System does not mean coordinates based on the world (planet earth). You could map all the points on earth into an AutoCAD drawing. What would you make 0,0,0? Where would you start? Personally Since earth is pretty much a sphere, I would set 0,0,0 to the center of the earth. Since most of us are not modeling the earth, lets stuck with relative coordinates to a site project. Your WCS will typically have 0,0,0 at a location on the site that is deemed the primary landmark. Thank you mappers and surveyors. You can also create any number of UCS’s you may need in a drawing that are relative to the WCS. Hopefully that all makes sense.

Figure 1 – Typical North Arrow arrangement

Most of the industry as I’ve been exposed to uses Up (Y-Axis positive direction) for North. (See figure 1.) This establishes the X-Axis as West(-) and East(+). Drawings come in a variety of shapes and sizes. Typically our drawing border is rectangular, and sometimes our content being presented is longer on the North/South Axis than the East/West Axis. For efficiency sake we rotate North to point to the left, but in reality all we do is rotate the border or the viewport in the case of Paperspace. The border/viewport is what adjusts to the content we do not actually physically rotate or change the North/South Axis. (See figure 2.) It is important to keep your model in your projects WCS (World Coordinate System) consistent. You can create as many UCS’s as needed for however many uses you may need.

Figure 2 – North to the Left

Most people have problems working on their drawings in this rotated mode. Note: I am using model space to show the concepts. In order to plot this drawing and annotate in the traditional method we can create a UCS to Rotate how we see our drawing. (See figure 3) Notice the UCSICON in the lower left corner. This is the origin of the UCS and it shows Y-Axis up and down, yet North is clearly left and right. We can annotate and work with our drawing in this state for personal preferences, and even plot form here. If we switch to World Coordinate System though, we can see the UCSICON is now showing Y-Axis going left to right as the north arrow shows.

Figure 3 – UCS for working
Figure 4 – WCS for real coordinates

If you wish to improve your knowledge, then I recommend getting to know some of the commands below.

UCS – use this command to set or create a UCS.

                Tip: Quickly reset to WCS by entering UCS[Enter][Enter]

DDUCS  – This is a Dialog based UCS command. It allows you to see any UCS’s defined in the current drawing as well as some other functionality.

PLAN     – This command sets the view of the current UCS (could be WCS) to X axis left to right and Y axist Up and down.

UCSFOLLOWS    – This is an AutoCAD Variable that controls if the PLAN view automatically adjust based on UCS settings. If you change the UCS, it will then automatically create the same effect as the PLAN command.

NAVVCUBE         – This controls the display of the Navigation Cube. Really useful for navigating in a 3D environment.

Navvcube – easily navigate the view of your model.

-VIEW   – (notice the dash in front) This can quickly get you to views if you don’t have the NAVVCUBE up or prefer the keyboard

TIP: -VIEW[Enter]_sw[Enter] This will switch you to SW isometric view

Other views include: _top ; _front ; _right ; _left ; _back ; _bottom

DVIEW – You can use this command for some different approaches to finding a desired UCS.

3DORBIT – Allows some free from manipulation of the view of your model.

Keep in mind that once you get the view the way you want, you can create a UCS based on that view by using UCS[Enter]V[Enter]

When working in 3D you will find you utilized a number of UCS’s to help facilitate your modeling. Just keep in mind that any actual coordinate references should be made in WCS. If you insert a block it will come in based on the current UCS. If you want it to come in based on WCS, make sure you reset to WCS before inserting it. When referencing other files, you will want to use the WCS in most circumstances. Same applies when using COPY w/BasePoint from one drawing to another. Make sure that both drawings are in WCS, unless of course you want to place relative to a UCS.

Good luck and let me know if this helps you understand the AutoCAD UCS.

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CAD Basics 101 – TEXT

 

I won’t bore you with rants about some of the, let’s say, subpar drafting efforts I have seen over the years. CAD has become more and more advanced and feature rich over the years, and I feel drafting quality has declined. Let’s try and help turn that around. Starting with Text. Text is used to communicate to the person reading the drawing. It is important that we communicate effectively and consistently. Text is basic so here are some basics checks for text.

  • Is text spelled correctly?
  • Is the text clear in meaning?
  • Is the text uncluttered and not overlapped by other line work in the drawing?
  • Is text positioned correctly?
  • Justified and aligned correctly?
  • Is text the right height for the subject matter (Body, Heading or Title)?
  • Text Width?
  • Layer?

Is your text spelled correctly? It is easy enough to verify your spelling. Yes we all make typos and get rushed, but get in the habit of verifying your spelling. Is the text clear? Does the text present the message you are delivering. Abbreviations are used quite frequently in drawings, but you should avoid them if possible, remember the goal is to deliver a clear message.

Is the text uncluttered and not overlapped by other line work in the drawing? Your text should not overlap or be overlapped by other elements in your drawing. Your text should be located in a spot that allows for text to be uncluttered. If your location does not allow for clean placement, you may need to break some of the background out or consider using a wipeout or text mask. I you choose wipeout or text mask methods, make sure you have good standards in place and have communicated the proper process for using them. Remember the printed result is what is used. If your system requires special settings for printing some of the issues that arise from wipeouts and text masks, then it is highly likely someone will print it incorrectly.

Is text positioned correctly? Your text should be relative in position to what you are identifying. A leader that stretches across 3” of printed material could easily lose its association. We will cover Leaders in another post. Is it justified and aligned properly. If you are like many CAD users, you simply copy other text in the drawing, change it and move on. This practice works great, but make sure the text you are copying is right to begin with. One of my personal favorites (read sarcasm) is when I copy a few lines of text, I then update that text, and then suddenly instead of it shifting as it should. The text actually changed position from where it should have been justified. For instance. It looked like it was centered, then when I changed the text to be longer or shorter, I discover it is Left justified. This is easily fixed, but, shows poor quality work on someone’s part. Make sure your alignment is correct. If you are placing an equipment tag inside an equipment outline and it fits centered and looks clean, great. If it is on the left or right of the equipment, Should it be left or right justified, these are things to look at. It may sometimes work, but it may also get confused with another piece of equipment. Check the presentation and make sure it is clear.

Is the text the right height, weight, width for the subject matter? Standards are what dictate these things. You should have some. If you are unaware of them, then ask. Text heights, weight, and width are often controlled by the text style. Text styles are a great way to maintain a consistent look in your drawings. Get to understand them. Note that text height and width are controlled at the text entity level and not the style level. The style simply sets the default for those. Text weight can be controlled in a few ways, Layer, color and by font selection. Again consult your standards on these. If the text is on the correct layer, you probably have the weight right. If the Font is set by the style correctly, you probably have the weight right. Color based plotting can control the weight as well, so keep in mind the best practice is to always draw bylayer for your color setting and not use the color setting at the entity level. Yes there are occasions when you should deviate. We will save bylayer topic for another post as well.

Some of you will relate to this topic, and think yes I wish more people understood this. If this is the case, forward this post on to them. Share the knowledge. I have found that typically most CAD users want learn and improve their skills. I’m sure all of us have opened a drawing and thought, “WHAT WERE THEY THINKING?” Some CAD Users are learning, CAD Systems like AutoCAD, have become so feature rich and full of functionality, often times new users are overwhelmed and not sure what the correct approach or setting should be. I am hoping to post more on CAD Basics on a regular basis. If you find these useful please share, comment or like. Thank you for reading.

Have an amazing day!