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Are you taking advantage of Fields?

What is a Field?

Fields are placeholders in a text string that are sourced from a data element or property value. Many of us have gotten accustomed to seeing a Drawing number automatically set in the Title Block, based on the file name. As shown below.

Sample Title Block using a Filename Field element to auto populate the Drawing number.

This is extremely useful for making sure you have the right drawing number in your title block. There are a number of advantages this offers. It prevents people from making a copy of the file and updating it instead of the actual drawing. Well it doesn’t actually prevent them from doing that, but then when they plot their file it stands out that it is a copy.

So if the file gets a new name, the drawing number automatically updates. Cuts down on confusion. It is pretty frustrating when you have two prints, that are different drawings but share the same drawing number. That will happen if someone copied the file and then failed to update the Title block Drawing number Attribute. What happens when you issue two different drawings with the same Drawing number? Ouch. That is a mess and I hope your Document control group catches that before sending it out to your client.

I think most of us can agree, that is a pretty cool feature. Fields have been around for a number of years now, 2005 I believe. That’s 15 years ago!

What else are they good for?

Fields can be expanded to use Sheet Set information and help keep more of your title block information more consistent. Project Name, Site Name, Project Site Location. All of those could be tied to an element in a sheet set or other property. I won’t dive to deeply into Sheet Sets or the other external properties you can take advantage in this Post, but recommend you look into what else you can do to take advantage of this feature. I will however talk about how you can take advantage of them in your drawing.

You can link data from one entity to another.

Sample Block Diagram using Field Data pulled from hidden text elements.

Above you can see the highlighted field area that are controlled by something else. These attributed blocks are automatically updated when a simple text string is updated. This will take your template to a whole new level, if done right.

So how do you set that up?

Fields are just another part of AutoCAD. The interface is not the most conducive for setting this up, but you can use AutoCAD straight out of the box and set this up. I have created some useful AutoLISP routines to make it more efficient, but I’ll show you how to do this with just AutoCAD.

First you will need the Source and the Destination AutoCAD entities present in your drawing.

S1 = The Instrument Type
S2 = The Tag Number Prefix
S3 = the Tag Number (minus prefix)

First lets get the S1 field Data to go into the ATTRIBUTE spot. Run the Field Command.

Select Object on the left side of the dialog.
Select the Select Object Button and then select the PT (Instrument Type) Attribute.
Next Select Value in the Middle (Property Column – Wow notice all those properties!) Then select Uppercase in the Right Column (Format – See the Preview). Highlight all the Text in the Field Expression Box, Right Click and Copy. Then Pick Cancel. (If you select OK AutoCAD will start placing an Mtext entity with the Field Expression as the text value. (you can hit cancel if you accidently hit OK)

Double Click on the ATTRIBUTE (Attribute Tag inside the Cable Tag Block) to edit the Value. and paste the value inside of it.

Notice the Value shows a Shaded PT in the Value Spot. That’s part 1 complete.

Next we need to repeat the process to get the other two parts of the CABLE Tag.

This one is slightly different as this entity is TEXT, so the Dataa we want is in the CONTENTS Property. Select Uppercase and Then highlight the Field Expression and right Click Copy.

Double click the Cable Tag Attribute (Currently showing PT).

Click in the Value Area and then make sure you are at the end of the text string type in a separator “-” and then paste the Field Value. Should now look like it appears above.

Let’s now get the third part of the Tag. Run the Fields Command and do the same steps but now pick the S3 (Source 3) Text Entity.

Now we have the Last part of the Cable Tag. Right Click and Copy. Make sure that Preview shows what you expect it to be “S3”

Double Click the Cable Tag Attribute and add the suffix (aka part 3).

Be sure to click to the end of the Value or you may erase the other two parts you worked so hard to get to. Add a separator “-” and then paste the next Field Expression (Ctl+C)

While we have the Last part Tag Number, we can go ahead and update the Instrument bubble to link to that value as well. Double Click on the ATT of the Instrument Bubble. and paste the value into the attribute.

Paste the same thing in this Attribute of the Instrument Bubble.

Ok That’s neat and all but that was a lot of work for two text values.

Yes it actually is. It would be way easier just to edit the values and be done. Would it? As we all know, change is inevitable. Copying is what we do a lot of, and consistency is king! Let’s copy 4 more instruments down. Update the Instrument Types to as shown below.

Make sure you copy the Instrument Tag, Cable and Tag as a group. Copying as a group creates new links associated with the new copies. Notice the Cable Tags have not changed. If you copied them right they will however actually be linked to the right Instrument Tag. If you copy something that has a link to another entity and that entity is being copied as well. AutoCAD will set the field data to be associated to the new entities. Pretty awesome feature. If you copy something that has a link to an entity that is not in the selection, then it leaves the field data association as is.

Why aren’t my cable tags updated?

There are a few things to understand about Fields. One the update based on the settings in the FIELDEVAL AutoCAD Variable.

Screen capture of the AutoCAD 2019 Help System for the FIELDEVAL System Variable. This is a Bitcode value so it means you can add the values together and make it work with multiple things considered. I Typically set mine to 31.

Once you have the FIELDEVAL set to Evaluate to at least include “Updated on regeneration,” Then you can simply do a REGEN or REGENALL to get the fields to evaluate the expressions.

Notice the Cable Tags are all updated properly.

Still more benefits. Change! The Project Just came back and updated the Site’s Prefix and the tag number for the instruments is now known. Site prefix is “PA-01” and the Tag Number the instruments share is 2003. Update the S2 Text string to “PA-01” ad the S3 Text String to “2003”. Regen and look at the results.

That was easy!

Now imagine if you used this in a wiring diagram and all your wire tags were linked to the instrument’s tag.

I hope this opens your eyes to some of the benefits FIELDS provide. If you do find you would like to start using fields, let me know and I can send you over a few useful routines for managing the field links much better than they FIELDS command.

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Title Blocks – The start of a good drawing

Title Block Sample

Title Blocks are a critical portion of any drawing. They represent the area of presentation, the purpose of the drawing, and data about the drawings properties. The Title Block is a critical part of your drawing and it will set the pace for how your quality and presentation are perceived by the person reviewing your Drawing. That person reviewing your Drawing could be the person constructing your design, reviewing your design, approving your design. It could easily be the person paying for the design, your client. The Title Block is a very important part of your drawing. GET IT RIGHT!

Make it a BLOCK

Title Block should in the least be a BLOCK. It is right there in the name Title BLOCK. Creating a Title Block should be something well thought out and standardized. All the components of your Title Block should be within the Block definition of that Title Block.

Use good Block creation practices

Insertion Point: The recommended insertion point should be the lower left corner of the sheet size that the Title Block will print to. So if your drawing size is an ARCH D (24×36) Drawing. The insertion point should be 0,0 and the upper limit should be 36,24. You could draw a sheet outline an place it on a no plot layer if desired, but using Paperspace properly will actually show the paper size of the intended sheet.

Margins: Keep in mind you will want a margin on your drawing as well. So the Sheet edges is not the place for Line work or information you want to show up on a Drawing Print. The Left margin is often used for binding a set together and is usually larger thna the other margins. A typical margin set is 1.25″ from the Left, 0.5″ from the right, 0.5″ from the Bottom and 0.5″ from the top. Margins are something that vary quite a bit across title blocks. Find a good margin that works for what your content is. Maximizing your margins as close to the sheet size as possible is not recommended as you will find content loss when a printer or plotter can not print as close to the paper edge as desired.

Rotation: The Title Block Rotation should be appropriate to your industry. My industry the title block is in Landscape, hence the 36,24 for the upper right corner, referenced above. When inserted at 0 rotation the Title Block should come in as desired.

Layers: Your Title Block will be in every Drawing of the project. Keep your layers to a minimum, keep colors, line weights, and linetypes to BYLAYER Settings. This allows for flexibility down the road. Think about plotting, different Color Tables, different Disciplines, Display of certain Title Block Elements…

Use Attributes: Text that is not meant to change in the Title Block can be plain Text, it will remain Static within a block, but attributes are the best things to use for the Dynamic Text content in your Title Block. You can set these up as fields to link these to drawing properties (a common one is to link the filename to the Drawing Number. (This all depends on your document numbering and file naming standards, you have those, right?) Attributes can easily be extracted, linked to properties in Sheet Set Manager or tied to a database system. With consistent data, you could easily generate a Drawing index or Drawing Status Report from that data, directly from your Title Block data! Attribute tags (names) should all be unique.

Text Styles: Non-Standard Fonts are not always available to every user, Try and make use of standard fonts and text styles. Highly recommend setting up and Text Styles specific for your border, so plotting and display are not affected by user updates to body text styles used. If you make use of standard text style for your title block with a different font, you could lose the formatting you had intended. See images below.

Disclaimer Text as intended to look.
Disclaimer Text after a simple style update from Romans to TXT

Revision Information: Revision History is an important part of a Title Block. Revision History can be part of the Main Title Block or it can be a separate block inserted into a designate are of the Title Block. My personal preference is to keep the Revision History Attribute data associated within the Main Title Block. Just make sure you set your Prompt Order is right.

Attribute Prompt Order: Attributes are great to use, but if your attribute prompt order is all out of whack it may cause frustration and lead to someone just placing text in your border. Not a good idea. When creating your block be sure to select the attributes in the order you want to be prompted for them. If you mess up the order, you can use BATTMAN to adjust the order, just make sure you set this up properly before using the Title Block on several hundred drawings. Keep in mind if you do, you at least can automate updating all those drawings, because you have a standard Title Block.

Drawing Information: Each industry will have its own required data elements. I recommend the following as a minimum.

Drawing Number
Revision (current issue of the drawing)
Project Name
Project Location
Project Number
Drawing Title Line 1
Drawing Title Line 2
Drawing Title Line 3
Drawing Title Line 4
Scale (Scale Factor of the Drawing)
Drawn Date (Date Drawing was started)
Drawn By (Initials or name of person that created drawing)

There are many more you could add (approvals, stamped by, engineer…)

Plot Stamp: A plot or file stamp will show some basic information that is useful that may or may not be evident in the title block data. A plot stamp will typically show the date the file was plotted, who it was plotted by, who the file was saved by and when, and sometimes the filename including the path. The plot stamp can easily be static text with fields within the Title Block. It does not have to be an attribute.

Plot or File Stamp

Title Block Name: The Name you give your Title Block is important. Use a defining name that uniquely identifies your Title Block. A generic name like “BORDER” could easily be the same as another block, and create a conflict in the drawing. If someone inserts another BORDER block into their drawing and accepts the Re-Define, then your Title Block suddenly looks like whatever the user is inserting. I recommend combining a few things to name your Title Block Name like CompanyName, sheet size, year created.
Example: ABCDrafting-ArchD-2020

Logos: Company Logos often make a Title Block look all that more professional. Problem is most Logos are Raster based images. I highly recommend NEVER EVER placing Images in your drawing files. Take the Time to create the Logo in AutoCAD and Create a separate block for the Logo. You can insert the Logo block directly into your Title Block or you can place it in the drawing in an area of the Title Block. Either way works. I personally place it within the Title Block Definition, so it is part of the Title Block. The benefit of having the log as it’s own block means if you ever get a new logo, you simply redefine the block and you are done. Easily automated as well.

Plotting: Your border is intended to plot to a specific size, and it should be plotted to that size. Not “FIT” Your scale should be 1=1, if you are plotting from Paperspace. This insures a scale factor reference is accurate. If you want to plot a drawing to a B-Size printer that is fine “FIT” works for that, but the sheet size for that page layout should properly be set to the drawings actual sheet size. If your drawing Sheet size is ARCH D (24×36) That is the size you should print to, even if you are plotting to a PDF file. Use the correct size, otherwise scaling is inaccurate and could lead to bid or construction errors. A scale bar on the drawing is often helpful in those cases.

Block Size: Your Title Block will be used in all your projects drawings, This could be 10 drawings it could be thousands. When you write the block to a file, you can see how big the file is in Bytes. A typical Drawing size (excluding complicated models) should be around 100-300K including your Title Block. The goal is to make your Title Block as least impactful on the drawing size as possible. A Basic Title Block (without a logo) can be around 30-50K. Adding a logo, depends on the complexity can easily bump that up above 100K. try and avoid that. Work on your logo to adequately show the logo, but also not be over detailed that it affects the drawing size significantly. Purge the Title Block File of anything unused. You can store some standard layers in the Title Block if Desired, just don’t go crazy.

A properly setup Title block can make your life as a Drafter much less complicated and present you and your company in a much more professional way. Quality and consistency start with that Title Block.

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Drafting Poll – Drawing Index Sheet

One thing I have discovered that is typically troubling for projects is data consistency. One place in particular is Drawing Title Block Data. Drawing Title Block data is used in the Titleblock, Drawing index, Drawing status reports, EDMS systems, transmittals and more. Problem is often times the data is incongruent because the data sources are often multi input sources instead of single source. Multi source invites data inconsistency. Take the following survey and compare how your processes to your peers. Start some discussions in the comments about your specific method works and what you would like to see improved in it.

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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 Advanced AutoLISP Teaser

So far I have discussed a few things about improving our industry through sharing of knowledge. AutoLISP has been around since I started with AutoCAD in 89’. AutoLISP continues to be a strong API for AutoCAD. This Post will just be a little bit of a teaser to see how interested you actually are in AutoLISP. I will show you a few quick things you can do at the command line inside AutoCAD that will hopefully pique your interest enough to come back for more.

First a couple of things to note. AutoLISP uses Parenthesis to enclose code segments. Some special things to pay attention to are for every opening parenthesis there needs to be a closing one. Similarly for every opening double quote, signifying a string, there needs to be a closing one.

Try this out (in typical programming tradition)

(defun C:HELLOLISP() (princ “\nHello World!”))

The above AutoLISP code will create a command called HELLOLISP that is now available within the AutoCAD Dwg Session you loaded it in. So give it a try. Type HELLOLISP at the command prompt.

Congratulations you just typed in and executed your first AutoLISP defined command!

That’s great and all, but what good does that do me? Well, it basically shows you how easy AutiLISP is to use inside AutoCAD directly from the command prompt. Let’s do some more, but directly with AutoCAD commands.

Open a drawing, any drawing that has something in it, hopefully a good collection of entity types, circles, lines, blocks, polylines, wipeouts, text… Make sure it is a copy of the drawing and not one you care to keep.

Once inside your drawing lets erase all the text in your drawing. There are a few ways to do it, but this is after all an AutoLISP lesson. So let’s use AutoLISP.

Start the Erase command, then when you are at the Select objects prompt, type in the following. (pay attention there is a single quote char and is special to the AutoLISP interpreter.

Select objects: (ssget “X” ‘((0 . “TEXT“)))
18 found
Select objects: [Enter]

All text (excluding MTEXT, Attributes, and any text inside blocks) should now be deleted.

Try it with other entity types. (“LINE” ; “CIRCLE”; “INSERT” (Block inserts); “LWPOLYLINE”)

In this intro we will not dig into what each things means, but we will show you some easy stuff to try.

Let’s move on.

AutoLISP can be used as an In line calculator. Take for instance those Scale Factors we talked about in the Scale Factors Post. With AutoLISP you can enter them directly at the command line instead of using a calculator. Say you want to scale something down to 1/48th of its original size. Start the SCALE command and select your object to scale, pick your base point and then when prompted for the scale factor input the following:

(/ 1.0 48.0)

Make sure you use the decimals. We will discuss why in later lessons.

You can use this even without a command. Try it:

(+ 37 2.5)

(- 20 19)

(/ 1.0 2)

(* 12 12)

You can use AutoLISP to access system variables. Imagine you are inserting symbol into a drawing and you don’t actually know the scale factor. Is it 64 or is 96. Assuming it is a scaled drawing and we are in Modelspace. Start the insert command, pick one of your symbols to insert and then when prompted for a scale factor try the following input.

(getvar “DIMSCALE“)

This will retrieve the current dimstyle’s scale factor setting. If you only use dimensions in Paper space this will basically be one. Again this is just to show some quick things to try.

What if you are working and you have two versions of the same file opened from different file paths. You can look it up using AutoLISP at the command line.

(getvar “DWGPREFIX“)

The result is your drawing file’s path.

AutoLISP is AutoCAD’s version of LISP. LISP Stands for List Processing, so it means we can’t have a in intro to AutoLISP without processing a list or two.

Find a circle in your drawing and let’s work with it. Type the following at the command line, then pick the circle.

(setq myCircle (entget (car (entsel “\nSelect Circle: “))))

The result is a list of all the DXF data for that Circle. Now let’s look at the parts. Type the following at the command prompt:

(foreach dxfitem myCircle (princ “\n”) (princ dxfitem))

You should see something like this:

(-1 . <Entity name: 7ffffb05f70>)
(0 . CIRCLE)
(330 . <Entity name: 7ffffb039f0>) 
(5 . 1EF) 
(100 . AcDbEntity) 
(67 . 0)
 (410 . Model) 
(8 . MyLayer) 
(100 . AcDbCircle) 
(10 20.5482 9.05521 0.0) 
(40 . 0.854867) 
(210 0.0 0.0 1.0) 
(210 0.0 0.0 1.0)

What is all that? (You may need to hit F2 to see)  It is the data that makes up the circle. The AutoCAD drawing is a VECTOR format and not a RASTER format. In other words it’s data and not dots. Let’s wrap up with a quick discussion of what some of these things are.

(0 . CIRCLE)

0 is the DXF code for entity type. This entity happens to be a CIRCLE, Hopefully you picked a circle.

(67 . 0)

67 is the DXF code for space, ZERO means Model Space, ONE means Paperspace.

(8 . MyLayer)

8 is the DXF code for Layer. This entity is on the MyLayer Layer.

(10 20.5482 9.05521 0.0)

10 is the code for coordinate, a circle on has one coordinate at the center.

(40 . 0.854867)

40 is the code for Radius. This one has a radius of 0.854867

Now you see how easy it is to use AutoLISP. Now looking at the above, note that using AutoLISP you can change all those values. You could change it’s Radius, it’s Layer, it’s center point…. And so much more.

I hope you have enjoyed this AutoLISP Teaser. If you would like to see more, let me know in the comments section.

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CAD Basics 101 – Scales Part 4 (Paperspace)

This is the Last part of Scale factors. Today we will discuss Paperspace and how scale factors work with Paperspace. Paperspace is a feature that was added to AutoCAD R11, That’s R11 in 1990 and not 2011. R11 also introduced ADS (AutoCAD Development System) a C programming interface that extended the AutoCAD API significantly and eventually migrated to what is now ARX (AutoCAD Runtime Extensions) a C++ programming interface. Sorry, I started down another tangent there. Back on track. So Paperspace introduced a whole lot of different ways to present your data, but for the most part, people left it alone and continued utilizing only Modelspace.

Paperspace was slow to start and if I remember right a Regen occurred at every zoom. This was painful on slower 286 and 386 systems. Fast forward to today and Paperspace has evolved significantly over the years. It has been abused and exploited in ways probably not intended by AutoDesk. For the purpose of this post I will stick to talking about a single Paperspace tab. Paperspace allows you to use your titleblock in a space that actually represents the printed media you intend for your drawing to be printed on. This means 1/4″ text is actually 1/4″ in Paperspace. This also means that symbols placed in Paperspace are inserted at a scale of 1. Some symbols are appropriate for Paperspace and some are better left in Modelspace. So for the most part there is no scale factor applied to your objects in Paperspace, this does not include scaling to compensate for unit conversions handled by AutoCAD in the background.

So, where does the inverse scale factor, presented in Part 3, come in? The Inverse scale factor is used when setting up your viewports inside Paperspace. A Viewport is essentially a window that allows for zoom levels. You could also think of it as a camera lens if you like. Your viewport is typically a small polygonal area, typically a rectangle that can be used to show Modelspace content on your paperspace drawing area. This is accomplished by creating a viewport using the MVIEW command. Once created your viewport will typically zoom the extents of the Modelspace and show that in your viewport. Your viewport can be set to a desired scale. Click on the viewport and look at the properties of that viewport. Near the bottom of the properties you will see standard scale and below that custom scale. If you do not see your scale factor in the standard scale drop down you can simply type in the inverse value of your scale in the custom scale input box. The list of scales presented in the standard scale is based on what scales are loaded into your current drawing. Drawings often have the extra scales purged to reduce file size. If you don’t see your scale in the list and want it you can use the SCALELISTEDIT command to add or delete scales. Once the scale factor is set. AutoCAD will zoom to the level based on the center of the viewport.

With your viewport set to the correct scale factor, you should now see your drawing as it will look when plotted. So how do you control what’s in the viewport. What if you have matchlines that you need to match, what if you have a particular area you want to show inside your viewport. There are a number of ways to configure your viewport to show where and what you want. If your matchline area is already in Modelspace and your viewport is proportional in size and proper scale to the matchlines, then you simply double click inside the viewport to make it active and use the ZOOM command with the Window option and pick the lower left and upper right corners to define your view, use your OSNAPS. Then switch back to Paperspace and set the viewport properties to locked to avoid shifting your view. “what if my viewport doesn’t match my macthlines?” You either make the matchlines match the viewport or the viewport match the matchlines. How? Let’s assume you want the viewport to match the matchlines.

Let’s talk about how to get the matchlines and the viewport to match proportionally and by scale, then talk about an easy way to make them match. Measure your matchlines rectangle, let’s stick with some easy ones say X direction is 100’ and Y direction is 50’. Our scale for this drawing is 1/4″ = 1’-0” meaning we have a 48 scale factor and a 1/48th inverse sale factor. This tells us that to find out how big our viewport dimensions need to be X distance is (100’ times 1/48th ) and our Y distance is (50’ times 1/48th). In this case that is X=25” and Y = 12.5”. Remember that we have to convert feet to inches before multiplying. Otherwise your measurement will result in a feet and decimal foot measurement. 12.5” would be 1.042’ hardly something we want to use as our measurement because there is a rounding issue involved. Inches are much better to work with than decimal feet. Yes Mappers will disagree, grin. Now just use the grips of the viewport to match the size we need. You can draw a box around your viewport and match it, or use lines to offset it, or use coordinates to get it there, but you will need to get the viewport to match the measurements.

Yes there are easier ways. You don’t even have to know the measurements of your matchlines. One simple way is to use Ctl-Shift+C to copy your matchlines with a base point, preferably lower left corner, and hopefully it is a closed polyline. Switch over to Paperspace, Ctl+v to paste it at the lower left corner of your viewport. Use the Scale command to scale the “Last” object and select the lower left corner. Then either use scale by reference (48 : 1) or provide the inverse scale factor of 0.02083333. Personally I would use the Scale by reference as it will be more accurate. 0.02083333 is a run on decimal and we obviously can’t run it out forever. Yes there are a number of alternate methods. I suggest you get familiar with different ways and discover which one works best for you. The outcome is the same regardless, or should I say the desired outcome. Hints at another method is CHSPACE command, but your viewport should be large enough to contain the object you are changing space from. Keep in mind it will move the object selected to Paperspace, so if you want to keep the Modelspace object, use a copy of it to move to Paperspace.

Hopefully this has been educational for you or has the potential to be useful to someone you know. This concludes the scale factor 4 part post. Take a look back if you missed any of them. Please comment and share.

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CAD Basics 101 – Scale factor Part 3

Now that we know how to get a scale factor for our drawing, how do we know which scale to use? Luckily there are standard scales to be used. Engineering, Architectural, Metric are some of the more common ones in use and are actually physical tools for measuring distances on actual drawings. If you have been in design or drafting for any length of time you have seen one. These are standards that we need to maintain and use. Yes we could make up our own to better suit our drawing or fit closer to the title block size, BUT we will avoid doing that, as it will cause problems and issues later.

One of my favorite sayings is “Just because you can do something, does not mean you should.” This is also why I am writing these blogs, to help educate some of the best practices in our industry and hopefully help my readers better understand and share the purpose of them.

Let’s talk Architectural Scales: You have heard 1/4″ = 1’-0” in my previous posts. That is an Architectural scale. Pretty easily to identify as it has inches and to a foot ratio. Here they are:

Standard Scales Scale Factor Inverse Scale Factor (used in paper space)
3” = 1’-0” 4 1/4th or 0.25
1-1/2” = 1’-0” 8 1/8th or 0.125
1” = 1’-0” 12 1/12th or 0.0833333
3/4″ = 1’-0” 16 1/16th or 0.0625
1/2” = 1’-0” 24 1/24th or 0.0416667
3/8” = 1’-0” 32 1/32nd or 0.03125
1/4″ = 1’-0” 48 1/48th or 0.0208333
3/16” = 1’-0” 64 1/64th or 0.015625
1/8” = 1’-0” 96 1/96th or 0.1041667
3/32” = 1’-0” 128 1/128th or 0.0078125
1/16” = 1’-0” 192 1/192nd or0.00520833

 

We will get to Paperspace next post, but I wanted to list those values used in paper space here.

Engineering scales are recognized by 1” equaling a multiple of 10’. Standard Engineering scales are:

Standard Scales Scale Factor Inverse Scale Factor (used in paper space)
1” = 10’ 120 1/120th or 0.0083333
1” = 20’ 240 1/240th or 0.0041667
1” = 30’ 360 1/360th or 0.0027778
1” = 40’ 480 1/480th or 0.0020833
1” = 50’ 600 1/600th or 0.0016667
1” = 60’ 720 1/720th or 0.0013889
1” = 100’ 1200 1/1200th or 0.0008333
1” = 200’ 2400 1/2400th or 0.0004167

 

Metric Scales are pretty nice as the metric system is based on factors of 10. Metric Scales offer something the other scales don’t. You can mix and match the units as they fit your need. Typically they are used as in mm to meters, but can be adjusted to be any metric distance measurements to any metric distance unit. Common Metric Scales are (using millimeters to millimeters to avoid any confusion:

Standard Scales Scale Factor Inverse Scale Factor (used in paper space)
1mm = 20mm 20 1/20th or 0.05
1mm = 25mm 25 1/25th or 0.04
1mm = 50mm 50 1/50th or 0.02
1mm = 75mm 75 1/75th or 0.0133333
1mm = 100mm 100 1/100th or 0.01
1mm = 125mm 125 1/125th or 0.008
1mm = 200mm 200 1/200th or 0.005
1mm = 250mm 250 1/250th or 0.004
1mm = 300mm 300 1/300th or 0.0033333
1mm = 400mm 400 1/400th or 0.0025
1mm = 500mm 500 1/500th or 0.002

 

Keep in mind if you start mixing the metric units, you will need to increase or decrease the values in the table accordingly. For instance if you said 1mm = 1m that would not b1 1=1 that would be 1 = 100. So if you applied the same 1mm = 100m scale you would need to increase the value in meters to be 10000. Because there are 100mm in every meter. So keep that part in mind the above table is mm to mm.

Note: There are different units you can apply to your drawing as well in AutoCAD. The system Variable INSUNITS controls what unit setting your drawing is using. You can access it or change it easily via the UNITS command. This allows AutoCAD to automatically apply unit conversions when inserting or referencing different drawings into your drawing.

Now we see a number of different STANDARD Scales we can use in our drawings. Stick with these and it will improve the quality of and make your drawings easier to use and manage.

A few reasons:

  • Industry standards already in place
  • More likely to have tools, physical and automated systems are more likely to work with standards
  • Drawing quality and consistency

Next up is Paperspace and how all this comes together.

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CAD Basics 101 – Scale factor Part 2

So, we have a Model needs a border with a scale factor of 48. Where else do we use this scale factor? Symbols, Text heights, Dimensions, Leaders, Linetype scaling, line work settings, Grid and snap settings and don’t forget plotting your drawing, and more I’m sure. I won’t go over every possibility, but will cover some to make sure we understand the concept. In another post I will help those of you that are wanting to learn more about automating with AutoLISP or other AutoCAD API’s, develop your own setup commands to help set drawings up consistently and take some of the headache out.

A Symbol is typically something that is used in drafting to represent something that otherwise might not stand out in a drawing. Things like a North Arrow, Section Marks, Material Bubbles, Receptacles, Lights, Welding callouts, and so much more. If your standard North arrow is 1.5” long on your drawing, then you want it to appear that way on every drawing. I will write another post on which way is up later, lot of debate on something that should be simple. Back on track… The North Arrow will be scaled consistently in your drawing to match the scale factor of the title block you are using or the scale factor of the drawing as established earlier. Keep in mind we are still not discussing Paperspace. We are focusing on understanding model space for the time being. It is also a good practice to maintain a position relatively close to the same spot on the drawings. You figure out the distance and the multiply that by the various scale factors of your drawings and they all come out the same, regardless of scale. It is important to start with a 1=1 drawing and figure out where it goes.

Text can get a little more depth, but it is the same principal as we discussed in the previous post. Take the desired plot size for the media you are printing to. Multiply that by the scale factor and that is the height of your text. I highly recommend setting up styles for each text height. At one point we had Leroy styles to match as close as possible to the Leroy pen sets that were used in manual drafting. This concept was very beneficial, because, when pen plotters took forever to plot a drawing, the occasional word being misspelled could be picked up by a manual drafter instead of sending the drawing to the plotter again and waiting 30-60minutes, and wasting ink and paper. Today’s printers take seconds to print, so that is not much of an issue any more. Another method of just using text styles like T125 for 1/8” text T25 for 1/4″ text has been around for a while. The 125 and 25 being the decimal equivalents of the fractions.B125 would represent Bold text and could either be a different font, or just simply shown on a different layer that plots with a heavier pen setting to make it stand out.

Let’s move on to Linetype scaling. If you load a linetype into your drawing, you will notice it shows up pretty good in a base drawing, but what happens when you draw that line in a drawing that has a scale factor of 48. That line was designed to be displayed in a drawing of 1=1, so at a scale of 48 it is pretty much too small to see. In AutoCAD there is a system Variable called LTSCALE. I have seen LTSCALE set at 1.0, 0.5, 0.375, and even 0.25. What does that mean? Well LTSCALE is a factor applied to the dashes dots and parts that make up the linetype. LTSCALE applies to all lines in the drawing. Line definitions are stored in the drawing file once loaded, so keep that in mind when you are trying to track down why two drawings are different looking. They may actually have different linetypes loaded for the same name. Using 1.0 for our test case we discussed last post would mean out LTSCALE should be 48.0. If we had a standard setting of 0.5 LTSCALE, then our LTSCALE would be 0.5 * 48.0 = 24.0.

NOTE: CELTSCALE is not the same as LTSCALE and something that should be set and stay set at 1.0. Nothing worse than tracking lines with individual settings of an LTSCALE. Yes entities can have individual LTSCALE settings, not a good idea to use this feature as a normal process.

Grid and Snap are important drawing tools to help you draw more consistently and accurately. If you are drawing in a 1=1 drawing like a wiring diagram, P&ID, Or even a legend sheet, you will find your snap settings are pretty simple, something like 1/4″ grid and 1/16” snap. This allows you to have snap points between the grid points that are always 1/16” apart. This keeps you consistent, and often keeps your fellow CAD designer Drafters happy. We will cover proper use of these in another post. Will snap and grid setting work in a drawing that has a scale factor? Of course it will. But keep in mind sometimes, dimensional data may force you to draw off grid and off snap. Parts are manufactured all over the world and dimensional data isn’t always cooperative from vendors. Make use of these tools. To use them in your scale factor drawings simply multiply the scale factor by the typical/standard setting and you have your new value.

That is all for this post. Next post we will cover Industry Standard Scales and why you should not make up your own. Good luck and thank you for reading. Sign in and leave some comments, or ask questions.

 

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CAD Basics 101 – Scale factor Part 1

Scale factors – Wait… That’s basic?? Yes, yes they are. Scales or scale factors are used to provide a method for presenting a large area or small area on the desired media size that is readable by the end user. What does that mean? Well, a scale factor allows us to present our design to the people that will be fabricating or building it and present it on a piece of paper that they can actually hold. Scale factors can be found using good ole math. There are factors used in Scale Factors to size the things presented on your drawings accordingly. What does it mean to draw 1=1 (one to one)? Why draw one to one? I thought you said we draw so that it fits on a smaller sheet. Scale Factors tend to confuse more drafters that it should. They are actually quite simple to understand and apply, but if you don’t understand their purpose it can become confusing on knowing when and how to apply them.

Scales allow us to draw a building that is 60’ wide and 40’ deep and show it on a piece of paper that is 22” x 34” long (aka ANSI D-Size). CAD allows us some advantages over traditional drafting on the board. CAD allows us to draw full size (1=1) then scale our title block (border) around the full size (model) and then print it to fit (using proper scale) within the boundaries of a piece of paper. Board drafting required us to draw at scale. This meant that if you wanted to represent the 60’x40’ building on a 22”x34” ANSI D Size drawing, using 1/4” scale (1/4” = 1’-0”), you as a drafter would draw a line 15” long to represent a 60’ side of the building. That line is 15” regardless and it is on a piece of paper, or vellum, or Mylar or whatever media was being used. The point is, it was scaled, down, for the paper and not full size (1=1). With CAD we can draw in our real world model and create a building that is in fact 60’ x 40’, then scale our border up to allow the building to fit inside our border. This means our border is actually huge 136’ x 88’ in size. No at full size this will not fit on a 22”x34” sheet of paper. We can plot this drawing using a scale factor to make it fit on the 22”x34” piece of paper. Please note when applying scale factor for drawings we always use a scale that maintains aspect ratio. Not to confuse you, but that means whatever scale we apply to one plane of the drawing we apply to the other plane. On paper we have 2 planes, X and Y. Let’s do the math. 1/4″ = 1’-0”. First let’s fix the units so they match. There are 12” in a foot. So now our equation is now 1/4″ = 12”. For an equation to work we are apparently missing something.

Apparently it’s Algebra:

Next let’s verify our equation:

We now have a scale factor of 48. So what do we do with it? Our scale factor is used to calculate the size of something relative to the paper size to appear appropriately with the actual size of the drawing. Our title Block is 22”x34”, so if we multiply 22” x 48 = 1056” -> 1056” = 88’: 34” x 48 = 1632” -> 1632” = 136’ that is the size of our border in our full size model. Please note we are NOT discussing Paperspace….yet. Everything we are discussing is Model space at this time. This same principal applies to text and Symbols. If we want text to be 1/8”(0.125) tall in our drawing (model) then we would need to apply the scale factor to the text. 0.125” * 48.0 = 6.0” This means your 1/8” text would need to be 6” in height to print at on a 22×34 ANSI D Size sheet of paper. So what would the height of the text be if we plotted this same drawing to 11×17 (ANSI B Size)? Notice the sheet size is a 1/1 ratio scaled by half of an ANSI D size sheet of paper. That means the 1/8” text would now be 1/16” in height on the printed 11×17 print.

We will continue this in my next post…. Coming soon.

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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!