Workshop: Introduction to 2D CAD (with Inkscape)

(Generally, this workshop is offered at least once every two weeks on a rotating basis. Check the Lab calendar for up-to-date availability!)

This tutorial will cover the basics of 2-dimensional Computer-aided design (CAD) using the software Inkscape.

You may have used a digital drawing program before - perhaps MSPaint, or Paint.net, for example. Most digital drawing programs end up storing 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 are 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.

Vector components:

• Nodes (for anchor points)
• Node handles (for creating Bezier curves)

Object and path properties:

• Stroke
• Fill

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.)

Layering is a way of organising the objects on the canvas. This is useful for perspective, 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).

Which machines in DaBL use vector files for fabrication:

• ULS PLS4.75 Laser cutter
• GCC Jaguar VLX Vinyl cutter
• Bantam Tools PCB mill

Preparing your designs for CAM

In certain situations, a manufacturing machine may say that it will accept your design file but might have certain restrictions on those design parameters so that the CAM software will understand. This section will explore some of the specific design procedures to setup your CAD design for a specific CAM software.

Laser cutting with UCP

The laser cutter's CAM software, universal control panel (UCP)