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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 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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