Of all the skills that I have picked up over the years as an engineer, there is one that has stayed with me and been a constant over the last three decades. It has helped me work on electronic projects, on furniture, on car parts, robots, and even garments, and it is likely that I will continue using it periodically for the rest of my career. You see, I am a trained PAD expert.
Don’t build this, it’s fundamentally flawed! Sometimes the front of an envelope is as effective as its back.
PAD, you ask? OK, it’s an acronym of my own coinage, it stands for Pencil Aided Design, and it refers to the first-year undergraduate course I sat many years ago in which I learned technical drawing to the old British standard BS308. If I’m making something then by far the quickest way for me to visualise its design is to draw it, first a freehand sketch to get a feel of how everything will sit, then a series of isometric component drawings on graph paper with careful attention to dimensions and angles. Well, maybe I lied a little there, the graph paper only comes in when I’m doing something very fancy; the back of an envelope is fine as long as the dimensions on the diagram are correct.
An Envelope Will Only Take You So Far
Working on paper is fine for the situations in which I tend to use it, running bits of wood or sheet metal through a bandsaw or pillar drill, leaning on the sheet metal folder, and filing intricate parts to shape by hand. It’s quick and simple, and the skills are intuitive and long-held. But it is of course completely useless when applied to any computer-driven manufacturing such as a 3D printer, and for that I will need a CAD package.
I’m not averse to CAD and my holding out with paper is only due to familiarity, but I have to admit that I have never found a package to which I have successfully made the jump. My need for it has been too infrequent to either take the time to scale the learning curve or for my new-found knowledge to stick. Reaching for the trusty pencil has always been the easiest option.
Hacky Racers in action (Mark Mellors)
All this has however recently changed, for as regular readers may have noticed I have a bit of a thing for the British Hacky Racer series. If I am to perfect my design for a slightly ridiculous contraption that will clean up on the track, it makes sense that I crowd my hackerspace with little 3D-printed scale models before breaking out the welding equipment and hacking a frame together with 25mm OD square tube. I thus need to pick a CAD package, learn it, and set to work.
So what are my needs? I’m a Linux user, so while Windows-only software is worth talking about in the comments for other people it’s less useful for me unless it’s easy to run under WINE. It’s also worth making the point that while I’m not averse to paying for good software as I did for my PCB CAD package I’m not anxious to shell out business-grade sums for something I’ll use only occasionally. This is an arena in which many of the offerings are aimed at enterprises, and I simply can’t justify spending hundreds or thousands as they can.
Round up the Usual Suspects
Given those prerequisites, there are still quite a few options. In the open source arena there are SolveSpace and BRL-CAD which I have never tried, OpenSCAD which is probably not my cup of tea (change my mind if you like), and FreeCAD which has been my tool of choice for previous attempts to dabble. I must have missed some others, what are your thoughts? If I don’t mind free-as-in-beer software there’s always TinkerCAD in my browser, is that up to a Hacky Racer chassis design in 25mm square tube? And if I’m feeling brave enough to play with WINE then perhaps I can make something of RS DesignSpark Mechanical.
My trusty pencil has given me stalwart service over many decades, but while I’ll not be hanging it up entirely it’s time to move into the 21st century for my design work. Can you help me decide upon which CAD package will suit me best? Have I even found all the choices within my criteria? As always, the comments are open.