Topics worth your time: the printer, the ink, and the moat; a field guide to choosing the right adhesives, why a BLDC motor's current rating != its power supply requirement, a novel approach to SLA printing eyeglass lenses, and the methodologies used in cost engineering.
P.S. A first look at our SF Tech Week event, for readers of the newsletter. Details here!
Interesting Links
Whether you care to admit it or not, the printer is one of the most accessible marvels of mass-produced engineering despite being the one product everyone loves to hate. Part of that frustration is because of the industry’s business model and the incumbents behind the closed ecosystem. Printer companies subsidize the machine at a loss and make up the margin (and more) on vendor-specific consumables. Putting the business model aside, the machine itself is a very interesting object. Ink can be ejected either by heaters that form bubbles and force droplets through a nozzle, or by piezoelectric printheads that apply voltage to a tiny element, causing it to change shape and achieve the same result. This all occurs at 10,000+ cycles per second (a single droplet is a trillionth of a liter), on a sub $100 machine. Despite the low price ceiling that prices new entrants out, Open Printer is trying anyway with an open-source inkjet printer designed around refillable cartridges.
Which Adhesive Should I Use? is a taxonomy of good bonds, or more specifically, glue types for two substrates under a variety of different bonding conditions. There is no such thing as an all-purpose glue, but there is a class of adhesives suited to nearly every combination of materials, preparation, temperature, and operating conditions. Take silicone, a notoriously difficult material to bond to plastic because of its low surface energy: for polycarbonate, the tool suggests a cyanoacrylate like Loctite 401 alone or with Loctite 770 primer, an adhesion promoter for low surface energy surfaces. For generalist conclusions on the best glues, Every Tool’s a Hammer is great reading. PVA for wood, paper, cardboard, and foam; contact cement for flexible or dissimilar materials; epoxy for fiberglass and permanent assemblies; and cyanoacrylate (super glue) for fast model work. As for the full technical literature, consider the Loctite Design Guide for Bonding.
How to Select the Right Power Source for a Hobby BLDC Motor is a useful explanation of a slightly counterintuitive detail about electric motors: the numbers printed on a motor are not the numbers you should use to size its power supply. For example, does a motor rated for 90 A and 2000 W need a 90 A, 2000 W power source? In most cases, nowhere close to the advertised ratings. A motor’s winding current != supply current; through pulse-width modulation, the motor controller turns a higher voltage, lower current input into the lower effective voltage and higher phase current used by the motor. The 90 A rating can be better considered as a limit on peak torque and heating than a demand on the power source.
The author’s recommended sizing procedure is to use the motor’s KV (a measure of motor speed per volt) and target RPM to choose a supply voltage, then use the required motor current at that speed to estimate peak power, adding 25% as a safety margin.
A reader submission on the future of eyeglass lens manufacturing. Some historical context: optical manufacturing hasn't changed in many years because material uniformity is a really hard problem. In fact, plastic eyeglass lenses have been cast, shipped, and ground the same way for nearly 80 years. Traditional manufacturing requires casting thick plastic "blanks" and grinding away up to 90% of the material for a single pair of eyes, creating massive waste. Azul 3D, a Northwestern spinout, is attempting to replace that flow with direct printing. Unlike conventional SLA which cures resin one layer at a time, Azul floats the resin on a flowing layer of fluorinated oil so the lens can print continuously without the light-scattering layer lines. In many ways, the industry where additive has had the most success (dental) is in many ways comparable to this market structure — custom, high-mix parts (material, curvature, refractive index) that traditionally require a large stock of tooling and physical blanks.
A practical exercise in cost engineering, applied to a locking mechanism used in a hands-free pet leash. Much of the thrill in designing and architecting the first version is simply asking, “Can we even make it?” Once the answer is yes, the question becomes: what does it take to make it at a cost that makes sense? For this design, that meant a series of DFM revisions to reduce cost within CNC machining, then a full change in manufacturing approach to die casting. That moved the part from an initial $45 quote to $2.50. A good rule of thumb is to start with low tooling costs and assume a higher part cost, then move to tooling once the design is stable to bring unit costs down.
And a couple of fun links to round out the week:
It only makes sense that WestMag’s CEO knows motors well enough to play GeoGuessr with builds from the latest DARPA challenge.
One of twelve “wares” to avoid when fundraising. Perhaps only a little fun.
DRCY: AllSpice’s AI Design Review Agent
Meet DRCY, AllSpice’s AI-powered agent built specifically for hardware design reviews. DRCY runs first-pass checks on schematics and datasheets to surface critical errors early, such as config errors, voltage mismatches, and much more. Hardware teams can spend less time on rechecks, more time innovating, and ship with confidence.
Startup News
Starcloud raised a $250M Series A extension to expand its satellite manufacturing capacity and develop larger orbital data centers. The company plans to launch two 8 kW compute satellites in 2027 before hoping to fly its larger Starcloud-3 spacecraft on SpaceX’s Starship. The extension was led by Manhattan West Ventures and included Nvidia, Cisco, Benchmark, and EQT.
Etched raised $700M at a $21B valuation to expand its specialized AI inference systems. The company sells ‘frontier inference clusters’ that can run any frontier model faster and at lower cost, framing its systems as an alternative to Nvidia for inference workloads. Jane Street led the round and is Etched’s first customer.
Gravis Robotics raised a $200M Series A from SoftBank to scale its construction-equipment autonomy systems. The company retrofits existing excavators with control hardware and software that can operate machines autonomously or with operator assistance.
Muon Space raised a $250M Series C to expand satellite production and develop additional mission capabilities. The company designs, builds, and operates mission-specific satellite constellations, and says it has received more than $10B in orders from customers including NASA, NOAA, Hubble Network, and the U.S. Space Force. Eclipse Capital led the round.
Commonwealth Fusion Systems raised $1B to complete SPARC, its fusion demonstration reactor, which the company says is about 80% complete. The MIT spinout uses superconducting magnets to confine superheated plasma in a tokamak reactor and aims to demonstrate net energy gain in 2027.
Open Jobs
More jobs added weekly on our job board. If you’re hiring, promote your open role here.
Early Career:
Sunday Robotics is looking for an Industrial Design Intern in Redwood City, CA
Philips is looking for a Manufacturing Engineer in Latham, NY
Mid-Level:
Westmag is looking for a Mechatronics Engineer in San Francisco, CA
Eight Sleep is looking for a Hardware Prototype & Test Engineer in San Francisco, CA
Senior to Staff:
Google is looking for a Senior Mechanical Engineering Manager, Project Suncatcher in Mountain View, CA
Impulse Space is looking for a Head of Build Reliability in Redondo Beach, CA
Slate Auto is looking for a Sr. Technical Program Manager (Remote)
Tools From Our Sponsors
Design & Simulation
Duro — AI-native PLM that centralizes part data, manages change orders, and connects the whole stack so your team can focus on execution, not administration.
nTop – Computational design to accelerate product development.
Onshape for Startups – Free access to Onshape Professional or Onshape Government (compliant with ITAR/EAR) for hardware startups and entrepreneurs.
Manufacturing
Loombotic – Instant-quote custom wire harnesses. Upload drawings or design online, fast turnaround.
Xometry — Instant quoting on custom parts, from R&D prototypes to high-volume production runs.
Fictiv – On-demand custom manufacturing from prototype to production.
Access Every Link We’ve Ever Shared 🎞️
Refer three friends to Hardware FYI and unlock our full archive.
Missed an issue? Hunting for that one link? Every tool, guide, and article we’ve ever shared is in here.
P.S. If you find something interesting—an article, tool, funding round, project, really anything—send it our way.
P.P.S. 20,000+ engineers, founders, and operators read this newsletter. If you want to reach them, get in touch.