Making the Form 2: first you torture it, then you ship it
Building 3D printers is complicated. Many different systems (optical, mechanical, electrical, and chemical) need to work in harmony to create high-precision 3D prints on your desktop. The more systems that have to work together, the more opportunities there are for things to go wrong.
This post is the first in a series where we’re documenting the process we went through to ship our latest creation, the Form 2. This is one of the most critical moments developing any complex piece of hardware — connecting and testing all the subsystems.
Engineered for Precision, Designed for Reliability.
We learned a lot designing and manufacturing the Form 1 and Form 1+. One of our biggest goals in developing the Form 2 was to drastically increase quality and reliability. From the first drafts of the system architecture in late 2014 to the first machines that will ship from the manufacturing line in a few weeks, everything was created with one goal in mind: reliability.
Design Verification Testing
“The product is guilty until proven innocent” — Bill Drislane
When building a complex product, it’s critical to identify issues as early in the prototyping phase as possible.
You wouldn’t have a final product to test, but you can start working on the subsystems. In fact, if you wait until you have your final product assembled to start your testing process, you’ve waited way too long.
Component Lifetime Testing
We want to make sure that all of our components live a long, happy life. To get there, we designed tests that pushed every major component to its physical limit. Each of the 50+ components that make up the Form 2 3D printer were put through the equivalent of 36 months of regular operation. This meant over 2 million cycles of machine parts sliding, turning, peeling, hoisting etc. All of our components had to survive this endurance test before they were considered for the next step in integration: subassemblies.
At the heart of stereolithography 3D printers are its lasers. The Form 2 has a 250mW precision laser that traces an optical path through the printer, curing layers of photopolymer resin.
Lasers are integral to the SLA 3D printing process; our optical systems have to undergo the most critical tests. First, we tested the optical power of the lasers. To be able to simulate thousands of hours of printing in a shorter period of time, lasers are run at higher than normal temperatures. In development and in production, we run a beam profile of every single laser. We use cameras and sensors specially designed to analyze and record laser spots to ensure each beam meets the right size, shape, and high power metrics.
One of our most ambitious efforts in building the Form 2 was to design and manufacture our own custom galvanometers. These are the very precise, rapid-response motors that guide the laser during the printing process.
For the Form 2, we needed a level of precision and reliability that we couldn’t find in off-the-shelf galvanometers, so we had to take on the challenge of building our own. Though galvanometers are relatively simple in terms of function and part count, the real work is in ensuring that the design is reliable and manufacturable. Design validation testing was an integral part of the development process.
In the galvanometer tests, we studied pointing accuracy, precision, and stability. Our tests exposed lasers and galvanometers to operational conditions beyond what they will ever experience in a printer. During these tests, we drove the components at higher powers, faster speeds, and high temperatures for hundreds of hours while monitoring their performance.
Lifting & Sliding
The Form 2 has a few critical moving parts; the build platform that raises and lowers during the build process (also known as the z-stage), and the sliding peel and wiper mechanisms. We expect both of these subsystems to see a lot of use, so we wanted to test for their longevity.
We developed test rigs that ran on “infinite loops” to identify when these components would fail. Both the z-stage and the slide assembly performed so well that we eventually stopped the test after 4 continuous months and over 2 million slide cycles. That’s equivalent to over 500km (310 miles)!
One system to rule them all
The final step in design verification testing is to fold all the subsystems together and test them extensively. The interplay between sub-systems provides different challenges than the individual pieces functioning alone. To ensure all systems work well together, we ran over 50 system-level tests, ranging from electrical overloading and static shock to extreme environmental testing.
So — we went ahead and put a fully assembled Form 2 in a dust chamber for six hours.
The Form 2 features an advanced optical engine comprised of lasers and precision galvanometers. And the number one enemy in optics is dust. To test the Form 2’s dust resistance, we placed a printer in a sealed chamber and blasted it with talcum powder for six straight hours. At the end of that ordeal, the Form 2 still printed at full performance. Technically, this means you could use a Form 2 in the Sahara desert, if you manage to find a power outlet.
Print All the Things
After we finished torturing all the subsystems, we spent hundreds of hours testing to ensure one thing: reliable prints.
One of the most important features of the Form 2 is its ability to make large, dense parts. In order to test this function, we designed custom models that we printed over and over on many machines to test variation and repeatability.
You can see one of our torture tests pictures in the photos above. It contains varying cross-sections, starting with a very thick base and then ultimately splintering into fine hair-like features. This, and other tests, help us ensure our print process can support a wide range of print requirements.
Into the wild
Testing and verification doesn’t stop with the first machine rolling out of the factory. The real test begins when our users start printing on the machine. After going through the rigorous testing cycles in-house, we are taking the Form 2 out into the wild with our beta testers program. Stay tuned for the next episode.
Huge thanks to Timur Senguen, Adam Lebovitz, and Gideon Balloch for their help crafting this note.
Learn more about what we do at formlabs.com.