Apr. 99:
Article by Jos H. Hindriks reviews how AutoCAD LT can be used to create quilts. Included are brief introduction of commands, instructions for developing a grid, drafting the curved block apple core, creating templates, adding seam allowance and developing Stencils. Excellent Graphic examples.

 


Issue 5: April 1999 continued
Editor: Sharla R. Hicks
Newsletter index for all issuesTable of contents for this issue

Quiltmaking and
AutoCAD LT Drafting Software

By Jos H. Hindriks, Dutchman Designs

Contents

Introduction: Why CAD?
Getting Started
Project 1 - Drafting a quilt top (Applecores Potholder, 8" x 8")
Project 2 - Drafting templates for piecing (Same Applecores Potholder)
Project 3 - Drafting a quilting stencil (Rail Fence Wallhanging, 30" x 30")




Introduction: Why CAD?

CAD stands for Computer-Aided Design. It is a generic name for software used by people like engineers and architects to draft projects like machines and buildings. CAD programs are the virtual "drawing boards" of today: geometrically oriented and very precise.

To develop quilts and images of quilts, I make frequent use of AutoCAD LT*, which is the "Lite" version of the regular AutoCAD*, a market-leading software package from Autodesk*. It offers most of the features of its larger brother but costs only a fraction of the price. Although that is still more than you pay for the average quilt design program, I think the investment is well worth it. AutoCAD LT can be purchased in software stores and through software catalogues.

AutoCAD LT is not specifically targeted to quilters and lacks the typical goodies like libraries of blocks and fabrics, yardage calculation and a quilter-friendly interface. But once you get the hang of it, you will find it to be a powerful and versatile tool to develop quilts, from the first stage to the last, from traditional to innovative. To list just a few design elements and quiltmaking tools it brings within your grasp:

- An n-pointed Lone Star (Six, eight or seventeen points, you name it).
- An off-center Mariner's Compass with 128 points.
- A fully symmetrical Kaleidoscope motif with intricate patchwork.
- A Celtic Knot.
- A Double Wedding Ring, any style.
- Any Foundation Paper Piecing design you come up with, on any scale.
- Intricately curved piecing templates, with quarter-inch seam allowances added.
- Fancy quiltwork stencils which are not available commercially.

A strong side of AutoCAD LT is customization. It allows the user to manually access, alter and exchange the basic elements that constitute a design. To me, this approach by far outweighs the shortcomings it may possess in comparison with quilt development software.

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Getting started

The program version on which this article is based is AutoCAD LT Release 2 for MS Windows* 3.1x. There are newer, more advanced versions on the market, but that should not cause any confusion here, for I describe only some of the essential commands, which are, as far as I know, the same in every version.

The minimum system requirements to run AutoCAD 2 for MS Windows 3.1x are:

  • MS DOS* 3.31 or later (5.0 or later is recommended).
  • Windows 3.1, running 386 Enhanced Mode.
  • 386, 486 or Pentium-based system with a math coprocessor.
  • Mouse or pointing device.
  • 8 Megabytes of RAM (recommended).
  • 16 MB of free hard-disk space.

When you boot up AutoCAD LT, you will see a window with the following contents:

  • Drop-Down menus at the top of the screen.
  • A work sheet area where the objects are drawn.
  • A Toolbar with command buttons, at the top of the worksheet area.
  • A movable Toolbox with more command buttons.
  • A keyboard command line at the bottom of the work sheet area.

Commands. The commands to change settings and generate or manipulate drawn objects can be entered by clicking with the mouse on the command buttons, by typing them in the command line or via drop-down menus. In this article, all AutoCAD LT command names are shown in capitals, e.g. DDRMODES, COPY, OFFSET. In this section, I introduce a few commands to set up your work sheet for quilt design. They give you an impression of the powers you hold when working with AutoCAD LT.
To exit a repetitive command, like multiple copying, press the right mouse button or the ENTER key.
To repeat the last command do the same: press the right mouse button or the ENTER key.

DDLMODES
This command activates the Layer Control dialog box and allows you to generate layers on which to place the elements of a drawing. By turning individual layers on or off, freezing/thawing them or locking/unlocking them, you can activate and de-activate the objects placed on them in various ways.

DDRMODES
AutoCAD LT supports snap-to grids, both orthogonal (squares and rectangles) and isometric (sixty-degree or equilateral triangles). The latter is perfectly suited to create 3-D illusions. Grids work like graph paper:

 

 Grid of squares and isometric grid

Figure 1
Grid of squares and isometric grid

The command DDRMODES activates the Drawing Aids dialog box to create a grid. To obtain a simple grid of squares, enter the following values:

- Check the "On" box under "Snap"
- In the box "X Spacing", enter "1".
- In the box "Y Spacing", enter "1".
- Check the "On" box under "Grid".
- In the box "X Spacing", enter "1".
- In the box "Y Spacing", enter "1".

Disregard the other boxes. Click on OK. Now you have a snap-on grid of squares that measure 1 x 1 Unit. These Units are relative, based on Floating-Point calculation. Their absolute lengths can be determined in the Print/Plot menu window. I will return to this further below in this section.

The work sheet area shows the grid as tiny black dots. They are the gridpoints, where the imaginary horizontal and vertical gridlines intersect. For reasons of clarity, I show these gridlines here in light grey instead of displaying the gridpoints. For an example, see Figure 1.

LIMITS
The work sheet has a rectangular shape. You can change its relative dimensions by entering new Limits values for the Lower left corner and the Upper right corner of the work sheet. The LIMITS function wants you to type these new values at the command line, in the form of two sets of co-ordinates, which correspond with the relative Units (see DDRMODES). For instance, if you define "Lower left corner" as "0,0" and "Upper right corner" as "35,25", you will have an area of 35 Units wide and 25 Units high on your screen, a nice setup for drafting small quilts. At any moment during a session, you can change these dimensions with the LIMITS command.

ZOOM
This command allows you to enlarge a part of a drawing on your screen to get a better hold of small objects. If you want to zoom out to the previous screen again, enter ZOOM and then "p" in the command line. If you want to view the whole screen as you last defined it with the LIMITS command, enter "all" instead of "p". The command ZOOM does not affect the actual size of the objects.

UNDO
A drawing session is nothing but a string of commands. During each session, AutoCAD LT maintains a temporary history list of this string. This is convenient at moments when you discover that your project is going the wrong way and you want to bring the drawing back to a state from where you think you can continue in order to reach your goal. You do this by repetitively entering the command UNDO, which every time removes and neutralizes the most recent command in the history list.
When you exit the program, the history list is gone. The drawing is saved in AutoCAD *.DWG format. When you open the drawing again, a fresh, blank history list is opened along with it that keeps track of the commands you use during this new session.

PLOT
This is the print command. It activates the Plot Configuration dialog box to prepare the drawing for printing and to set up your printer or plotter. The most important options at this moment are:

- "Print/Plot Setup & Default Selection...", to tell AutoCAD about the printer you use.
- "Inches" and "MM", two radio buttons to choose English or Metric as the unit of measurement.
- "Plotted Inches (or MM) = Drawing Units", to set the absolute length of the relative Unit.
- "Preview", to preview your drawing and its positioning on the paper.

The absolute length of the relative AutoCAD Unit is crucial when you make piecing or appliqué templates or quilting stencils. I usually combine a grid with squares of 1 x 1 Units (see DDRMODES) with corresponding absolute values of 1 inch to 1 Unit.

DXFOUT, PSOUT, WMFOUT
Use these file export commands to make drawings legible to programs that do not recognize the standard AutoCAD *.DWG format.
DXFOUT exports a drawing into a *.DXF (Drawing Exchange Format) file, which can be imported in graphic design environments such as CorelDRAW!*, and further processed.
PSOUT exports a drawing into a PostScript file, which is a common format in the desktop publishing world.
WMFOUT exports a drawing into a *.WMF (Windows Metafile Format) file, which can be incorporated in MS Windows environments such as MS WORD*. I publish some of my commercial patterns in this way.

 


In the following sections of this article, I will describe three small AutoCAD projects for quilters, in which I introduce some basic drawing commands. To make it a bit more exciting, I will focus on curved lines. The Projects are the following:

Project 1 - Drafting a quilt top (Applecores Potholder, 8" x 8")
Project 2 - Drafting templates for piecing (Same Applecores Potholder)
Project 3 - Drafting a quilting stencil (Rail Fence Wallhanging, 30" x 30")

They are meant to give you an idea of what you can already do with just a few commands at hand. The User's Guide that comes with the program will help you further; it is one of the clearest software manuals I have come across. I strongly suggest AutoCAD users to consult it in conjunction with this article, because it provides valuable command shortcuts and helps prevent pitfalls beginners are easily dragged into.

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Project 1 - Drafting a quilt top
Workpiece: Applecores Potholder, 8" x 8"

The goal of the first Project is to create a graphic, black-and-white draft of the following square Potholder design:

Applecores Potholder

Figure 2
Applecores Potholder

Applecores, also known as Double Axes or Friendship Curves, are patches with four curved sides. The Potholder shown in Figure 2 has twenty-five of them: nine whole ones in the middle, twelve half ones at the edges and four quarter ones in the corners. The narrow reddish frame around the design represents the binding.

Anatomy of Applecores. The light-green colored Applecores are vertically oriented, while the darker green ones between them lie horizontally. Yet they are of the same shape, with two opposite sides "caving in" (concave) and the other two "bulging out" (convex). The concave sides of the light green Applecore patches are the convex sides of the dark green Applecores, and vice versa. In other words, the Applecores pattern is a pure tessellation, or tiling, of seamlessly interlocking copies of one and the same shape. Every side is one-fourth of a circle. When you extend the sides to make the circles complete, you see the following interlacing pattern of circles emerge:

Anatomy of Applecores

Figure 3
Anatomy of Applecores

The outlines of the Applecores are shown in black, the remaining parts of the circles in lavender. The circles intersect at regular intervals that are marked by gridpoints of the grid of squares. Notice that in every Applecore, the two opposite sides that are "bulging out" belong to one and the same circle. Another interesting detail: the lavender-colored circle arcs are, too, a continuous pattern of Applecores.

Drafting an Applecore. First I set up a grid of snap-on squares like I described in the previous section under DDRMODES. To create the "atom" of an Applecore, the curved side, I need to have a circle of the right size. In our current project, the circle touches the four points of a square made of two by two gridsquares.
I Enter the command CIRCLE. AutoCAD asks me to pick a point as its center (the gridpoint marked "C" in Figure 4, left). Having made sure that I am working in SNAP ON mode, I click on a randomly chosen gridpoint in the work sheet area to define it. Now AutoCAD requires me to click on a second point to mark the length of the Circle's radius (the purple line "r" in Figure 4, left). I click on the opposite corner of one of the four gridsquares that touch the center. In Figure 4 (left), I picked the lower left gridsquare.

Drawing the whole Circles

Figure 4
Drawing the whole Circles

To re-create the interlacing pattern of Circles, I use the command COPY and click on the circle as the object to be copied. I need five Circles to draw my Applecore. Therefore, I choose the option "Multiple" ("m"), so that I can make more than one copy of the Circle. I position the five new Circles as shown in Figure 4 (right). Then I press the right mouse button or the ENTER key to exit the COPY command.

I now have the "raw material" to distill the four sides of my Applecore from. The next step is to remove the excess lines.
This is done with the command TRIM. AutoCAD asks me what object to use as the cutting edge and I click on the Circle in the middle of the group. Then AutoCAD lets me pick out the objects to be trimmed and I simply click on those parts of the four other Circles that are outside the central Circle, in succession. (marked by "x" in Figure 4, right).

Trimmed Circles, the four Circle Arcs and an Applecore

Figure 5
Trimmed Circles, the four Circle Arcs and an Applecore

With the trimming done (Figure 5, left), I remove the central Circle (Figure 5, middle): it only had to serve as the cutting edge. Now I have four Circle arcs, each one pointing in a different direction.
To get my Applecore, I use the command MOVE to bring the lower arc up by two Units (gridsquares) and the upper one down, also by two Units (Figure 5, right). Because I have kept my Snap mode on all along, the arcs land exactly there where I want them to be.

Drafting the Potholder. The Applecores Potholder consists of the same Circle arcs as described above, as well as straight lines that mark the edges of the design.

First, I use the command COPY to make multiple copies of the four Circle arcs and create a field of Applecores (Figure 6). The command SNAP ON, which enables the Snap mode, ensures exact positioning of the copies.

Drawing a field of Applecores

Figure 6
Drawing a field of Applecores

Then use the command LINE to draw a square of eight by eight Units (Figure 7, left). After completing the square, I exit the LINE drawing mode by pressing the right mouse button or the ENTER key.

The straight lines cut the Circle arcs at the edges of the design in half. To remove the outer halves I apply the TRIM command, with the straight lines functioning as the cutting edges (Figure 7, right).

Trimming away the excess lines

Figure 7
Trimming away the excess lines

Now that I have completed the "Body of the Potholder", so to say, I proceed with drafting the binding. I want it to be a quarter of an inch wide and since I have decided that my AutoCAD Unit is going to be one inch long, I need to draw the outer edges of the binding one fourth of a Unit away from the Body.
With my current Snap mode of one Unit enabled, I cannot access the spaces between the one-Unit gridpoints, so I need to adjust my Snap settings. With the command DDRMODES, I call up the Drawing Aids dialog box:

- I keep the "On" box under "Snap" checked.
- In the box "X Spacing", I replace "1" with "0.25".
- In the box "Y Spacing", I replace "1" with "0,25".

I keep the "Grid" settings unchanged and click on OK. My work screen shows the same Grid division of one by one Unit, but I can move my mouse pointer across it at intervals of one fourth (0.25) of a Unit. With the command LINE, I draw the outer edges of the binding, with nicely mitered corners:

Applecores Potholder, finished draft

Figure 8
Applecores Potholder, finished draft

My drawing measures 8½ inch by 8½ inch. To print it exactly to size, I enter the PLOT command. In the Plot Configuration dialog box I enter the value "1" both for "Plotted Inches" and "Drawing Units", to print my Potholder draft exactly to scale. But before I click on OK, I suddenly realize that my Letter-sized paper is not large enough to accommodate the entire drawing. So I change the "Plotted Inches" value to 0.5, thereby reducing the dimensions of the drawing by one half. My printer gives me a picture that measures exactly 4¼ by 4¼ inch.

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Project 2 - Drafting templates for piecing
Workpiece: same Applecores Potholder

Suppose I like doing things the hard way and want to make separate templates for all the four different kinds of patch shapes in my Applecores Potholder. They are the whole Applecore (Figure 9, patch "A"), the half Applecore cut lengthwise (Figure 9, patch "B"), the half Applecore cut crosswise, through the waist (Figure 9, patch "C") and the quarter Applecore, cut both lengthwise and crosswise (Figure 9, patch "D"). In Figure 9 they are shown as templates, with seam allowances added:

Piecing templates for the Applecores Potholder

Figure 9
Piecing templates for the
Applecores Potholder

The light grey lines are the future seamlines. This means that the spaces enclosed within these lines are the actual patches as they will appear in the finished quilt top and that the areas outside them are the seam allowances. In AutoCAD I can create seam allowances that are exactly a quarter of an inch wide everywhere, regardless the outlines of the patch: square, rectangular, triangular, polygonal or even with curves like in an Applecore.

Lines and Polylines. The secret of adding seam allowances lies in the proper formulation of the seamlines in the template. They need to be welded into a single, self-contained object, as opposed to a collection of loose lines and circle arcs like the ones that make up the Potholder draft from Project 1. Simple lines generated with the LINE command won't do the job; the situation calls for a more powerful tool named Polylines.
Unlike a regular Line, a Polyline can comprise more than one element. It can consist of several straight lines and circle arcs and still be a single object. Such constituent elements are called vertexes and they are linked together through nodes like the shackles in a chain. When this "chain" forms a continuous circuit like a bicycle chain, the Polyline is defined as "closed". Thus, if the four circle arcs of an Applecore are connected by nodes all around, the Applecore is a single, closed object.

In Figure 10, I show how I draw the four Applecore patch shapes, in three steps.

Drafting the patch shapes

Figure 10
Drafting the patch shapes

Step 1 (Figure 10, top). I draw the circle arcs and straight lines, which are the "atoms" of the patch shapes, on a grid with the Snap mode enabled. The Snap value and the Grid value are both set to "1". Circle arcs can be converted into Polyline vertexes, but regular straight Lines cannot. To draw them, I use the PLINE (Polyline) command instead of LINE. AutoCAD asks me to set the starting width and the ending width of the Polyline, but I simply press the ENTER key, thereby maintaining the default width "0". As a result, my Polylines will be printed in their minimum width, rendering my paper templates as precise as can be. Every time I finish a Polyline, I press the ENTER key to exit the PLINE command..

Step 2 (Figure 10, middle). With the help of the command TRIM, I remove the excess bits of circle arc outside the patch shapes. Then I press the ENTER key.

Step 3 (Figure 10, bottom). Using the same command TRIM, I remove the excess bits of straight Polyline outside the patch shapes. Then I press the ENTER key.

Closing the Polylines. My patch shapes now consist of the proper Polyline vertexes but these aren't connected into closed objects. The arrows in Figure 11 tell where the "loose joints" are located. You don't see the "loose joints" themselves in the picture, but they are there all right. Notice that in the quarter Applecore (bottom right), the two straight lines are already connected by a node (no arrow). This happened when I drew them as a single object within one PLINE command.

"Loose joints"

Figure 11
"Loose joints"

To perform the closing, I type the command PEDIT (Edit Polyline). AutoCAD inquires which Polyline needs to be edited and in response I click on one of the circle arcs of the top left patch shape in Figure 11, which is the whole Applecore. AutoCAD now presents a choice of options and I select "j" for "Join". Then, with my SHIFT key down, I click on all four circle arcs of the shape to select them as a group. Finally, I press the right mouse button or the ENTER key. My Applecore is now a closed Polyline. By pressing ENTER again, I exit the PEDIT command. To proceed with closing the next patch shape, I type PEDIT again or simply press ENTER to re-activate the previous PEDIT command.

Tip: To verify whether a Polyline is closed, type PEDIT and select the Polyline in question. If AutoCAD's first option says "Open", which is used to un-close the polyline, then the closing has been succesful. If it says "Close", there are still "loose joints" to be dealt with.

Outward offsetting. It's time to draw the seam allowances. This is done with the command OFFSET (Figure 12).

Offsetting the patch shapes

Figure 12
Offsetting the patch shapes

In the command line, AutoCAD tells me to determine the desired distance through which to offset and I enter "0,25". Then it asks me to select an object and I pick the top left one, the whole Applecore. The next query is "Side to offset?" and in response, I click on a randomly chosen point outside the patch shape. Now my whole Applecore is finished and AutoCAD wants to know which object is next. So I repeat the process until all four shapes have seam allowances. Then I exit the OFFSET command.
Like the patch shapes, the newly generated objects (shown in purple in Figure 12; arrows added for visualization of the offsetting process) are closed Polylines.

Tip: In order to reach the objects more easily with the mouse pointer during offsetting, you can turn the Snap mode off.

The templates are finished and I am ready to print them out. I enter the PLOT command and in the Plot Configuration dialog box I make sure that the values of "Plotted Inches" and "Drawing Units" are both "1". Then I click on OK.

I carefully cut out my printed templates and paste them on a sheet of plastic or dense cardboard. As a matter of fact, some companies that issue precision templates for patchwork use AutoCAD to draft them.

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Project 3: Drafting a quilting stencil
Workpiece: Rail Fence Wallhanging, 30" x 30"

My square Rail Fence design is simple and straightforward, in only two colors and without any border. The color division of the twenty-five Rail Fence blocks make the quilt top appear like a field of tessellating (interlocking) dumbbells, each consisting of three bars of the same color.
I want to enhance this notion of tessellation through quiltwork and decide to do so with a pattern of curves that follow the repetition of the dumbbells. In Figure 13, the quilting is shown in teal-colored lines:

Rail Fence design with fancy quiltwork

Figure 13
Rail Fence design with fancy quiltwork

Anatomy of the quilting pattern. The intertwining curves may look intricate and hard to grasp, but the pattern is entirely based on one simple elliptical form. Figure 14 shows a part of the quilt design projected on a grid of squares. The Rail Fence blocks measure twelve by twelve gridsquares (Units) and the patches four by twelve gridsquares (Units). Their outlines are drawn in black. The quilting curves are teal.

Anatomy of the fancy quiltwork

Figure 14
Anatomy of the fancy quiltwork

One of the curves is highlighted in green. This single curve is all I need to draft my quilting template. The purple dots mark the gridpoints it intersects. The deep purple dots are positioned at the four corners of one Rail Fence block; the lower two are also the endpoints of the curve. To trace the quilting pattern on my quilt top, I will only have to move my one-curve stencil about the blocks and turn it at ninety-degree angles.

Drawing an Ellipse. AutoCAD defines an Elllipse as a circle, but with a difference between the vertical and the horizontal diameter. The Ellipse that I need as a basis for my curve is eighteen Units wide and eight Units high:

Drawing the Ellipse

Figure 15
Drawing the Ellipse

I enter the command ELLIPSE and type "c" to pick a gridpoint as its center ("C" in Figure 15). My "Axis endpoint 1" is the gridpoint located four Units above the center ("E1" in Figure 15) and my "Axis endpoint 2" is nine Units to the left of the center ("E2" in Figure 15). The finished Ellipse is shown in green.

Drafting the quilting stencil. The quilt top measures five by five Rail Fence blocks, or sixty by sixty Units. I want it to be a small wallhanging of thirty by thirty inches, so I count a half inch for every Unit. Determining the absolute measurements is important at this stage, because the width of the curved slit to be cut out of the stencil sheet depends on it.

I want the slit to be an eighth of an inch wide (0.125"). Using the OFFSET command (see Project 2), I enter the distance value of 0.125 and then offset my Ellipse twice, once to the intside and once to the outside (Figure 16; purple arrows added for visualization of the offset process).

Offsetting the Ellipse inwards and outwards

Figure 16
Offsetting the Ellipse inwards and outwards

The offset ellipses, shown in purple, are 0.125 + 0.125 = 0.25 Units apart. That is an eighth of an inch, due to the fact that in this Project, my gridsquares are a half inch high and wide instead of one inch. In other words, my printed quilting stencil draft will show a slit of 0.125" (an eighth of an inch) wide.

As the next step, I draw small auxiliary lines (shown in purple in Figure 17) that intersect the endpoints of my curve (the lower two deep purple dots in Figure 14). They serve as the cutting edges to remove the section of the ellipse caught between them, with the help of the command TRIM. I also draw two tiny circles with a radius of 0.125 Units, to mark the upper two corners of the Rail Fence block (compare the upper deep purple dots in Figure 14):

 

Trimming the offset Ellipse; adding points for positioning

Figure 17
Trimming the offset Ellipse; adding points for positioning

My draft is completed. With the PLOT command I call up the Plot Configuration dialog box and adjust my absolute measuring values: "0.5" for "Plotted Inches" and "1" for "Drawing Units". When my printout is done, I paste it on a plastic quilt stencil sheet and trace the slit and the two small circles with a burner (or double-bladed hobby knife). The end result looks like this:

The finished quilting stencil

Figure 18
The finished quilting stencil

The stencil has all the elements required for marking my quilt top: the curved slit and the four points to align it with the corners of the Rail Fence blocks.

 


 

A note on web images. All images in this article were drawn in AutoCAD LT Release 2 for MS Windows 3.1x. and exported to *.DXF files using the DXFOUT command. They were imported in CorelDRAW! and colored; all colored fields are closed Polylines generated in AutoCAD LT. From there, they were exported as *.GIF files. It is these *.GIF pictures that you are looking at.

Can your quilt design program do this?

Figure 19
Can your quilt design program do this?

Without the help of a program like AutoCAD LT, I wouldn't have been able to publish my patterns the way I wanted them, or share my quilt designs on the Internet. With the exception of a handful, all images on my website began their career as AutoCAD *.DWG drawings.

Jos


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Questions? Comments? E-Mail Jos H. Hindriks
For questions about specific AutoCAD LT commands, please consult the AutoCAD LT User's Guide

Copyright 1999, Jos H. Hindriks
* The trademarks mentioned in this article are the properties of their respective owners
Dutchman Designs is in no way affiliated with any of the companies mentioned in this article.

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