Tech Today: 3D Printing for the 12-Volt Industry

WORDS BY BRIAN SCHURG

Also known as “additive manufacturing,” 3D printing has been around for a few decades now. Mainly used in medical fields (think false teeth) and for rapid prototyping for industry use, it took a while to become somewhat mainstream. Of course, I use the term “mainstream” loosely. The technology has been wildly popular for prop makers, cosplayers, and those who need or require a Yoda head or a baby Groot. But for the 12-volt industry, not so much.

In the past handful of years, CNC has been picking up speed in our industry, a revolution of sorts, yet additive manufacturing has been a hold-out. Unfortunately there tends to be a stigma surrounding 3D printing, ongoing misunderstandings and bad assumptions. While many of my friends picked up lasers and routers, I decided to go to 3D printing because I saw some potential. At first, they all snickered. They laughed or made fun of how small it was, but I chose not to listen.

A Complex, Multi-Layered Tool Like any process, 3D printing has its pros and cons. It will never replace a CNC laser or router. It just can’t compete with the speed or tolerance those machines have, but it can exploit the third dimension in ways those machines cannot. The main thing I was concerned with was that it can make products that are essentially fabricated right off the platform, and they are done with ABS plastic—a plastic that anyone in the install bay is familiar with. I figured if I needed to paint or wrap the project, there would be no problem. It’s just ABS, no hocus pocus needed. Plus, I can model them with the correct tolerance ahead of time. (Say what?)

I get asked questions about 3D printing all the time. Which printer is best? What material should I use? What’s a “slicer”? Do I need to learn CAD? Which CAD program is the best one? Does it really take 24 hours to print parts? Unfortunately it would seem every question leads to a much deeper conversation.

Years ago, I didn’t know which machine to buy, either. How could I? The market has more machines than you can shake a stick at, and they seem to be multiplying faster and faster. So, I looked at what was cheap! I bought a $160 Anet kit. I figured the kit would allow me to get more familiar with how the machine worked, I could customize it and if it didn’t work out, then no big deal. I printed two things using PLA with that machine—items that came on the SD card in the kit. I realized there was more to this technology than just letting a machine do its thing. Much more.

Taking a Look at Materials and Temperature Resistance

You may be asking yourself, “Why bother with ABS if you can make things out of PLA easily?” Well, it comes down to the products I wanted. I was looking for something that would work well in a vehicle environment, be durable, and easily worked into fabrication techniques I was already familiar with. PLA is great for making things that will be used mainly in a house in which the climate is regulated. It’s a low temperature plastic that doesn’t lend itself well to the higher temperatures a car is subjected to.

But then, you may ask, “There are other plastics available on the market. What about those?” This comes down to what works well with other fabrication techniques. Super glue works exceptionally well with ABS, and so does primer, paints and contact cement. Other plastics, such as polyethylene and polypropylene, tend to be higher maintenance, both on the machine and in the bay. There are higher temperature plastics available, and more to come, but ABS seemed best for what we need in the industry.

Temperature was the reason my first go-around with ABS was a bit of a disaster. It can be a fickle material and it tends to shrink when it cools. When this happens, it warps and, worst of all, the part lifts and sometimes come off the build plate entirely. I ended up rigging a makeshift enclosure around my $160 printer out of flat rate boxes from USPS. That was a game changer. Things were printing exceptionally well. That was, until I decided to “upgrade” and built an enclosure that was far more sealed. The heat it held in was a bit too much, causing printer parts to warp and rendered the printer useless.

It appears these parts were made of PLA plastic, and couldn’t withstand the heat from ABS prints. Nowadays when asked which machine is best, I like to recommend something like a Creality CR10. It’s all metal, can support big builds, and it’s capable of doing ABS right out of the box. It doesn’t have an enclosure, so build one.

An enclosed CR10 is quite a nice setup, but I’ll admit, huge. I did manage to get the Anet back up and going, and got a few parts off it, including ABS replacement parts for the future, and the first Aussie Iron holder.

Using Applications and Programming I have since upgraded to an enclosed printer and haven’t looked back. The iron holders were an unexpected hit. I have made hundreds of them and continue to do so. Those led into other fun projects like business card holders, and even things like tap handles and clocks. This helped me to get my head around the software involved in making something from nothing. You must become proficient at CAD. Everything from there is trivial.

It all starts with a dream, right? A vision? A sketch? That’s where any CNC project starts as well, but in CAD. There are quite a few CAD programs out there that seem to work well for our application. I’m not going to act like I’m well acquainted with them all, but I know enough.

AutoDesk seems to be the go-to for anything CAD related, and they offer a plethora of programs for different applications. What appears most popular is Fusion 360. This can be downloaded for free as an educational program. Once you start making some real money with it, you should probably start to pay because you get better support at that point. It’s a very powerful program, and I’m certain I’ve used about two percent of its potential.

It may come with a bit of a learning curve, but take it slow. Initially I got into making projects in an Autodesk program called 123D Design. It is designed with 3D printing in mind, and it’s a boiled down version of Fusion 360. This has since been cut from Autodesk’s lineup, but you can still find it for download. I still use it for customized Aussie Iron holders or even business card holders. Although my templates could be imported into Fusion 360, I just prefer to use 123D, as it can be faster.

Applying 3D Printing Techniques

Car audio fabrication is quite a wonderful thing if you step back and look at it. We really don’t conform to any set of rules. We use metal fab, wood fab and composites (plastics). We have to know how to upholster, do body work, paint and texture surfaces. We even have to know how to hook up electronics properly. It’s definitely a melting pot of disciplines. This is where CNC fits in. It’s been around for decades, but sometimes I feel certain techniques or technologies need to be kicked around the 12-volt bay to really figure out the potential. Stack fabbing is one such technique I have seen grow in popularity over the years and it fascinates me how we can integrate aspects of a design in ways we can only dream of when using other techniques. I tend to look at 3D printing as a miniature form of stack fabbing, but the layers aren’t ¾-inch. It is more along the lines of .2 mm thick, and sometimes even smaller.

Basically, we are telling a machine with a hot glue gun where to lay a bead of plastic, and we do it over and over until we have something. This command is done through what’s called a “slicer” program. We take our project from CAD, and import it into a program that turns it into hundreds (thousands?) of little layers that the machine understands.

Cura, Slic3r, and Simplify3D are the top contenders in this arena. I’ve used them all, and they all seem to work great. At first, you can probably just use the pre-determined settings for your machine and materials. For the most part you will have success doing this, and once you get familiar with it, you can start tweaking the settings if need be. There are hundreds of settings in a slicer (too many to expand upon here) but the basic settings get the job done.

There are a couple of important points you must remember. First, you don’t have to make your parts solid. Doing them in 20 to 50 percent infill will be sufficient to form 90 percent of the items you are making. Second, don’t worry about printing at .1mm layer height. If you have to finish the part (paint, wrap, etc.) you can use .2 or even .3mm height. Don’t waste your time.

The difference between a 10-hour print and a three-hour print can literally be the layer height alone. Don’t get caught up in expecting a mirror finish from the machine; it’s super easy to post-process parts. Look at it this way: It’s 1,000 times easier to finish than a resin saturated fleece sub enclosure, and we have done that how many times already?

I mainly use the printers for smaller projects like tweeter and/or mid placement, switch panels, or DSP controller locations. The 3D printer has been godsend for capturing an OEM feel for many installs.

From the 3D Printer to the Bay: Volkswagen GTI

One project in particular is the Volkswagen GTI shown here. This was a returning customer who received a rather extensive job in his Nissan Frontier years ago. Unfortunately, he wrecked the truck and had to get a new car. He didn’t have it two weeks and he was at the shop looking to get a new system that would “blow the old one out of the water.” I figured this would be a good project to try some printing on.

My team and I decided to lose the little triangle corner window. I’m not sure who at VW thought that was a good idea, so we tinted it and decided to build over it.

The first step in the process is to take photos, mainly from the side and from the door opening, toward the windshield. These are imported into CAD to have a precise template to draw from. Plus, it gives me an idea of angles of the pillar for later adjustment.

The pictures are imported into Fusion 360. Taking measurements from the actual pillar, I’m able to scale the drawing to the proper size. I start with the spline tool and do a rough outline of the potential pod shape.

After having a basic concept of shape and size, I continue drawing features that will be brought out later in the CAD process. Things like trim rings, emblems, speaker locations, gap tolerances and even magnet provisions are sketched in prior to bringing the drawing into three dimensions.

Once the overall concept is determined, the part can be pulled into 3D. This is done using the “extrude” command in Fusion 360. Essentially what you are doing is adding thickness to your CAD drawings. From there we can chamfer, fillet, slice, make holes and whatever else needs to be done. Here, you can see the final pod with all the parts, as well as a colored rendering to give you an idea of the finished product.

Notice the tweet and mid locations are tilted. The mesh was modeled at one point so I could determine which templates I would need for pressing the grilles.

When the drawing is done, I export it as an STL file and prepare for the actual print. I take the time to figure out how I want to do this. Some parts need to be printed cleaner than others, so I export the parts that are seen in the final product in a high poly count. The baffle is done in low poly. I do this mainly to keep my computer from hating me. From there I put the parts into the slicer software and prepare for printing. The baffles are done at .3mm layers with a 20 percent infill. Now I can mirror the part for the driver and passenger sides.

Now we move on to mock up, and see if there is anything that needs to be cut, trim or grinded to get these into the right position. The passenger side needed exactly three layers of cardboard to achieve proper orientation.

These pillars presented a unique challenge in that I had to build the lower portion that went around the triangle window, and down beside the dash. This was done using conventional ABS sheet plastic (see, ABS again!).

Grille cloth is then stretched over the entire assembly. The pillars are covered in fabric from the factory, so I end my grille cloth midway and resin the whole thing. The factory fabric absorbing resin aids in blending the new area to the old.

While the resin cured, I set out to finish the grille sections. The printed parts don’t take much to finish. I coated them with CA glue, sanded it and hit them with some SEM high build primer. I opted to do a few different colors here to coordinate with the interior of the car—satin black trim, gloss black inner and a touch of silver. I made 3D logos for the grilles as a kind of OEM premium speaker package look. The mesh for the grilles were pressed and trimmed, and assembly was started.

Once sanded and smoothed, the pillars started coming together. They were wrapped in OEM material and test fitted. Once everything looked good, the pillars were fitted to the vehicle one last time, the speakers mounted, and the grilles were magnetically attached to the baffle. One really nice aspect of using CAD is the ability to create perfect mirror images, although the Audiofrog logo had to be slightly altered to look appropriate.

And there it is—ready for tuning, and ultimately, enjoyment.