STL files are everywhere. When there’s something to 3D print, it’s probably going to be an STL. Which, as long as the model is good just as it is, is no trouble at all. But sooner or later there will be a model that isn’t quite right in some way and suddenly project progress hits a snag.
When models interface with other physical things, those other components may not always be exactly as the designer expected. Being mindful about such potential inconsistencies during the design phase can help prevent problems, but it’s not always avoidable. The reason it’s a problem is because an STL file represents a solid model as a finished unit; it is not really intended to be rolled back into CAD programs for additional design changes.
STL files can be edited, but just like re-modeling a component from scratch, it can be a tricky process for those who don’t live and breathe this stuff. I’ll describe a few common issues related to STLs that can hold up getting that new project together, along with ways to deal with them. Thanks to 3D printing becoming much more commonplace, basic tools are within reach of even the least CAD-aware among us.
Back in the 70s when I started getting interested in electronics, tons of magazines catered to the hobbyist market. Popular Electronics was my favorite, and I think I remember the advertisements more than anything, probably because they outnumbered articles by a large margin. Looking back, it seemed like a lot of ad space was sold to companies hawking the tools and materials needed for wire wrapping, which was very popular for prototyping in the days before solderless breadboards were readily available. I remember beauty shots of neat rows of small, gold posts, with stripped wires wrapped evenly around them.
To the budding hobbyist, wire wrapping looked like the skill to have. With a huge selection of posts, terminals, and sockets for ICs and discrete components, as well as a wide range of manual and powered wrapping tools, it seemed like you could build anything with wire wrapping. But fast forward just a decade or so, and wire wrapping seemed to drop out of favor. And today — well, does anyone even wire wrap anymore?
[Dickel]’s robot MDi #4 has been in progress for several years, but what we wanted to draw your attention to is the way the parts have been fabricated and what kind of remarkable results are possible with careful design, measurement, cutting, and finishing. Much of MDi #4 was made by hand-cutting and drilling sheets of high impact polystyrene (HIPS) with a utility knife and layering them as needed. Epoxy and aluminum provide gap filling and reinforcement of key sections, and fiberglass took care of one of the larger sections.
The process [Dickel] follows is to prototype using cardboard first. Parts are then designed carefully in CAD, and printed out at a 1:1 scale and glued to sheets of polystyrene. Each sheet is cut and drilled by hand as necessary. Layers are stacked and epoxied, embedding any hardware needed in the process. Two examples of embedding hardware include sealing captive nuts into parts with epoxy, or using aluminum to add reinforcement. After some careful sanding, the pieces look amazing.
Scroll down a bit on that project page and you’ll see plenty of great photos of the process [Dickel] used. A video highlighting the head and a video showing the careful work that goes into making each part are embedded below.
[Tommy] is a one-man-shop making electronic musical things, but that’s not what this post is about. This post is about the outstanding prototyping post-mortem he wrote up about his attempt to turn his Four-Step Octaved Sequencer into a viable product. [Tommy] had originally made a hand-soldered one-off whose performance belied its simple innards, and decided to try to turn it into a product. Short version: he says that someday there will be some kind of sequencer product like it available from him, “[B]ut it won’t be this one. This one will go on my shelf as a reminder of how far I’ve come.”
The unit works, looks great, has a simple parts list, and the bill of materials is low in cost. So what’s the problem? What happened is that through prototyping, [Tommy] learned that his design will need many changes before it can be used to create a product, and he wrote up everything he learned during the process. Embedded below is a demo of the prototype that shows off how it works and what it can do, and it helps give context to the lessons [Tommy] shares.
[Dickel] always liked tracked vehicles. Taking inspiration from the ‘Peacemaker’ tracked vehicle in Mad Max: Fury Road, he replicated it as the Mad Mech. The vehicle is remote-controlled and the tank treads are partly from a VEX robotics tank tread kit. Control is via a DIY wireless controller using an Arduino and NRF24L01 modules. The vehicle itself uses an Arduino UNO with an L298N motor driver. Power is from three Li-Po cells.
The real artistic work is in the body. [Dickel] used a papercraft tool called Pepakura (non-free software, but this Blender plugin is an alternative free approach) for the design to make the body out of thin cardboard. The cardboard design was then modified to make it match the body of the Peacemaker as much as possible. It was coated in fiberglass for strength, then the rest of the work was done with body filler and sanding for a smooth finish. After a few more details and a good paint job, it was ready to roll.
There’s a lot of great effort that went into this build, and [Dickel] shows his work and process on his project page and in the videos embedded below. The first video shows the finished Mad Mech being taken for some test drives. The second is a montage showing key parts of the build process.
[JesusGomez] has certainly put work into his Vertical Laboratory concept. There’s a bit more to the idea than simply using 3D printed parts to move electronics from the desktop onto a metal pegboard, although that part is certainly nicely done. There are 3D models for securely mounting various hardware such as Raspberry Pi, Beaglebone, ESP32, cable management, breadboards, and other common parts to a metal pegboard. Instead of having parts and wires splayed across a workbench, it can be mounted and organized vertically. Having a project or prototype mounted on pegboard is easier to store, saves room, and frees up desk space in small work areas. It also makes for an organized and visually pleasing layout.
A clever piece of design is in the plastic mounts that he created. He wanted parts to remain securely mounted unless intentionally removed, allow different mounting orientations, and to never require access to the back side of the pegboard. To accomplish this, the parts use a combination of pegs that slide-lock with bendable sections that act as lock tabs. Once mounted, the parts stay put until the lock tabs are released by gently prying them out of position. Since mounting and removal can be done entirely from the front, wall mounted pegboards with inaccessible backs can be used.
Starting a new project is fun, and often involves great times spent playing with breadboards and protoboards, and doing whatever it takes to get things working. It can often seem like a huge time investment just getting a project to that functional point. But what if you want to take it to the next level, and take your project from a prototype to a production-ready form? This is the story of how I achieved just that with the Grav-A distortion pedal.
Why build a pedal, anyway?
A long time ago, I found myself faced with a choice. With graduation looming on the horizon, I needed to decide what I was going to do with my life once my engineering degree was squared away. At the time, the idea of walking straight into a 9-5 wasn’t particularly attractive, and I felt like getting back into a band and playing shows again. However, I worried about the impact an extended break would have on my potential career. It was then that I came up with a solution. I would start my own electronics company, making products for musicians. Continue reading “Taking a Guitar Pedal From Concept Into Production”→
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