Everything needs to be designed, at one point or another. There are jobs for those who design kitchens, and stadiums, and interplanetary spacecraft. However, there are also jobs for those who design cutlery, hose fittings, and even toilet roll holders. [Eric Strebel] is here to share just such a story.
[Eric] covers the whole process from start to finish. In the beginning, a wide variety of concepts are drawn up and explored on paper. Various ideas are evaluated against each other and whittled down to a small handful. Then, cardboard models are created and the concepts further refined. This continues through several further phases until it gets down to the fun part of choosing colours and materials for the final product.
Watching the effects of cost and manufacturing process shape the finished item is instructive as to how the design process works in the real world. The toilet paper holder itself is an interesting unit, too – using adjustable magnetic detents to enable one-handed use, as well as including a cell phone holder.
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.
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.
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.
Just to be clear, the primary goal of the Papas Inventeurs (Inventor Dads) was to have the kids make something, have fun, and learn. In that light, they enjoyed a huge success. Four children designed, made, and sold laser-cut napkin rings from a booth at the Ottawa Maker Faire as a fun learning process (English translation, original link in French.) [pepelepoisson] documented the entire thing from beginning to end with plenty of photos. Things started at proof of concept, then design brainstorming, prototyping, manufacture, booth design, and finally sales. While adults were involved, every step was done by the kids themselves.
It all began when the kids were taken to a local fab lab at the École Polytechnique and made some laser-cut napkin holders from plywood for personal use. Later, they decided to design, manufacture, and sell them at the Ottawa Maker Faire. Money for the plywood came from piggy banks, 23 different designs made the cut, and a total of 103 rings were made. A display board and signs made from reclaimed materials rounded out the whole set.
In the end, about 20% of people who visited and showed interest made a purchase, and 60 of the 103 pieces were sold for a profit of $126. Of course, the whole process also involved about 100 hours of combined work between the kids and parents and use of a laser cutter, so it’s not exactly a recipe for easy wealth. But it was an incredibly enriching experience, at least figuratively, for everyone involved.
[ByTechLab] needed an enclosure for his R820T2 based RTL-SDR, which sports an SMA connector. Resolving to design and 3D print one in less than a day, he learned a few things about practical design for 3D printing and shared them online along with his CAD files.
The RTL-SDR is a family of economical software defined radio receivers, and [ByTechLab]’s’ enclosure (CAD files available on GrabCAD and STL on Thingiverse) is specific to his model. However, the lessons he learned are applicable to enclosure design in general, and a few of them specifically apply to 3D printing.
He started by making a basic model of the PCB and being sure to include all large components. With that, he could model the right voids inside the enclosure to ensure a minimum of wasted space. The PCB lacks any sort of mounting holes, so the model was also useful to choose where to place some tabs to hold the PCB in place. That took care of the enclosure design, but it also pays to be mindful of the manufacturing method so as to play to its strengths. For FDM 3D printing, that means most curved shapes and rounded edges are trivial. It also means that the biggest favor you can do yourself is to design parts so that they can be printed in a stable orientation without any supports.
This may be nothing that an experienced 3D printer and modeler doesn’t already know, but everyone is a novice at some point and learning from others’ experiences can be a real timesaver. For the more experienced, we covered a somewhat more in-depth guide to practical 3D printed enclosure design.
[ByTechLab]’s desire for a custom enclosure was partly because RTL-SDR devices come in many shapes and sizes, as you can see in this review of 19 different units (of which only 14 actually worked.)
We’ve reduced printed circuit board design to practice so much that we hardly give a thought to the details anymore. It’s so easy to bang out a design, send it to a fab house, and have ten boards in your hands in no time at all. All the design complexities are largely hidden from us, abstracted down to a few checkboxes on the vendor’s website.
There’s no doubt that making professional PCB design tools available to the hobbyist has been a net benefit, but there a downside. Not every PCB design can be boiled down to the “one from column A, one from column B” approach. There are plenty of applications where stock materials and manufacturing techniques just won’t cut it. PCBs designed to operate in space is one such application, and while few of us will ever be lucky enough to have a widget blasted to infinity and beyond, learning what’s behind space-rated PCBs is pretty interesting.
Since 1999, one of the more popular manufacturers of test equipment has been Agilent, the spun-off former instrument division of Hewlett-Packard. From simple multimeters to fully-equipped oscilloscopes, they have been covering every corner of this particular market. And, with the help of [Kerry Wong] and his teardown of an Agilent LCR meter, we can also see that they’ve been making consistent upgrades to their equipment as well.
The particular meter that [Kerry] took apart was an Agilent U1731B, a capable LCR (inductance, capacitance, resistance) meter. He had needed one for himself and noted that while they’re expensive when new, they can be found at a bargain used, but that means dealing with older versions of hardware. For example, his meter uses an 8-bit ADC while the more recent U1733 series uses a 24-bit ADC. The other quality of this meter that [Kerry] made special note of was how densely populated the circuit board is, presumably to save on the design of a VLSI circuit.
While we don’t claim to stump for Agilent in any way, it’s good to know that newer releases of their equipment actually have improved hardware and aren’t just rebadged or firmware-upgraded versions of old hardware with a bigger price tag attached. Also, there wasn’t really any goal that [Kerry] had in mind besides sheer curiosity and a willingness to dive deep into electronics details, as those familiar with his other projects know already.
While the jury is still out on 3D printing for the consumer market, there’s little question that it’s becoming a major part of next generation manufacturing. While we often think of 3D printing as a way to create highly customized one-off objects, that’s a conclusion largely based on how we as individuals use the technology. When you’re building something as complex as a rocket engine, the true advantage of 3D printing is the ability to not only rapidly iterate your design, but to produce objects with internal geometries that would be difficult if not impossible to create with traditional tooling.
So it’s no wonder that key “New Space” players like SpaceX and Blue Origin make use of 3D printed components in their vehicles. Even NASA has been dipping their proverbial toe in the additive manufacturing waters, testing printed parts for the Space Launch System’s RS-25 engine. It would be safe to say that from this point forward, most of our exploits off of the planet’s surface will involve additive manufacturing in some capacity.
But one of the latest players to enter the commercial spaceflight industry, Relativity Space, thinks we can take the concept even farther. Not content to just 3D print rocket components, founders Tim Ellis and Jordan Noone believe the entire rocket can be printed. Minus electrical components and a few parts which operate in extremely high stress environments such as inside the pump turbines, Relativity Space claims up to 95% of their rocket could eventually be produced with additive manufacturing.
If you think 3D printing a rocket sounds implausible, you aren’t alone. It’s a bold claim, so far the aerospace industry has only managed to print relatively small rocket engines; so printing an entire vehicle would be an exceptionally large leap in capability. But with talent pulled from major aerospace players, a recently inked deal for a 20 year lease on a test site at NASA’s Stennis Space Center, and access to the world’s largest metal 3D printer, they’re certainly going all in on the idea. Let’s take a look at what they’ve got planned.