Workshop: Introduction to 2D CAD (with Inkscape)
(Generally, this workshop is offered at least once every week on a rotating basis. Check the DaBL calendar for up-to-date availability!)
This tutorial will cover the basics of 2-dimensional Computer-aided design (CAD) using the software Inkscape.
For more tools included in Inkscape not covered in the workshop, visit the wiki page for Inkscape.
You may have used a digital drawing program before - perhaps MSPaint, or Paint.net, for example. Many drawing programs, including the two previously mentioned, store the image you create in bitmap form: it is made of an array of pixels, and each pixel is assigned a certain color. There is another way, however, to store image information: in the form of vectors. A vector is nothing more than at least two points in 2D space, in between which a line is drawn. In actuality, vectors stored as equations for a line, defined by the xy values of each of the points.
Why does this matter? Unlike a bitmap - which can be recreated in the real world with something like a dot-matrix printer - a vector drawing can be interpreted by a fabrication device which has xy controls and which understands equations. These devices make it possible to fabricate much more intricate designs than devices which work with bitmaps.
There are many vector-drawing applications; each effectively has the same capabilities, just organized differently. In DaBL we use Inkscape, because it is cross platform as well as free.
- Nodes (for anchor points)
- Node handles (for creating Bezier curves)
Object and path properties:
The Inkscape UI
Inkscape UI is fairly straightforward:
- Tools panel on left
- Drawing canvas in middle
- Snapping panel on right
- Floating windows which can be docked (including Stroke and Fill, Layers, et al.)
What you can do
- Draw free hand lines, shapes, rectangles, and squares
- Fill in the stroke, change the color of an object on the right hand side or at the bottom
- You can do full color or gradients
- Additionally, stroke paint can make the stroke style bigger and change the color. For ex. make the stroke red to cut out shapes on laser cutter
- Plane line is ideal for laser (stroke needs to be 0.025 mm in width)
- For laser cutter engravements the color would need to be black
- Outlining a letter would need to be in blue
- eraser erases the paths for lines, works with the free hand lines
- Bring in pictures into inkskape, drag it in from google (go for outlines of images to make things easier)
- Import image, right click, path, trace bitmap, embedded image, live preview (makes it black and white), change threshhold to ensure outline is clear and visible
- Save images as svg for laser cutter
- Add layers, change the name of layers, delete layers, hide layers
- Layer names displayed at the bottom
- Generally, don't need to draw in page, you can draw anywhere
- Put two objects together with union at top right
- Snapping is similar to grouping, you can put a star in the corner of where the rectangle meets it automatically goes to the corner
- Enable snapping on the right hand side and it only snaps to boxes
Layering is a way of organizing the objects on the canvas. It operates in a vertical hierarchical manner, the top most layer will correspond to the top layer of the image and so on. This is useful for perspective because you can make individual layers visible and invisible, as well as for grouping.
Make sure, as with all digital design packages, to save early and save often. You will want to make sure to save as type .SVG (Scalable Vector Graphics)
Preparing your designs for CAM
If you're eventually going to be using one of DaBL's machines to fabricate your design, some considerations are in order. Each machine's CAM software has a specific way of interpreting your design; as such, setting up your design in a certain way may work for one type of machine, but not another. Each of the following CAM packages will allow import of 2D vector files:
By the end of this Workshop, you should:
- understand what vectors are.
- know how to resize the canvas and change the default measurement units.
- know how to work with vectors, including how to split and merge them.
- know how to work with layers.
- understand and utilize stroke and fill to change the appearance of elements.
- know how to change the default color system and manipulate the palette.
By the end of this Workshop, you should be able to:
- create your own vector elements, such as lines and shapes.
- move elements around the canvas.
- snap elements to other elements.
- save your design as a PNG and as a PDF.