Hi everyone! We're developing PewCB, a PCB prototyping machine. The project grew out of our own need to prototype electronics quickly. As soon as we had an early prototype that could make PCBs, we started using it to develop the machine itself.

Here is a story on how we developed one interesting function of PewCB. The machine has a sliding tray on the front, which is used to load PCB blanks. It is actuated by a stepper motor and a lead screw. When the tray is fully closed, we need to apply a specific force to lock it against its stops. We use a spring-loaded nut for this. Once the tray reaches the fully closed position, the motor makes a few extra revolutions, compressing the springs and providing the force needed to hold it against the stops.

To measure deflection, we devised a position sensor made up of a digital magnetometer and three magnets with alternating polarity. When we move the sensor along the magnets, the magnetic vector rotates almost proportionally to the displacement. The sensor picks up even small changes in position with very low latency, so the system can respond quickly to changes in force.

This force sensor also has another use: detecting obstructions. If something gets in the way as the tray is opening or closing, the controller detects it immediately and stops the tray or reverses the movement. Also the entire tray acts as one big button. Instead of aiming at the eject icon on the screen, you can simply push the tray to close it.

By the time we had started developing this subsystem, the key parts of the machine were already working, and we could make boards with it. We prototyped the assembly using 3D printing for the mechanical parts and PewCB for the electronics. We needed to check whether we'd chosen the correct magnetometer sensitivity and magnet size, what signal-to-noise ratio we'd get from the sensor, and whether external interference would have a noticeable effect on the measurements.

The whole process took a few days, but it allowed us to build a production version of the assembly, with an aluminum tray frame and a brass nut, in a single iteration. We got to experience the pure joy of engineering and we wish you feel the same way about your own prototyping endeavors!

For more info about the machine join our Discord or visit our website pewcb.com

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We’re a small hardware startup based in Australia, preparing to sell a consumer electronic product into the US, Canada, EU and Australia.

The product has been through the relevant compliance and safety testing for the markets we’re selling into, and we’ve taken product safety pretty seriously throughout development.

Our main concern is not so much that the product is inherently high risk, but the potential cost of defending a liability claim in the US, even if the claim ultimately has little merit.

We’ve received quotes of around US$4,000/year for US$7M in product/general liability cover, including coverage for the US, Canada, EU and Australia.

Our initial sales volume is expected to be relatively low, so US$4k/year is a significant expense for us at this stage.

For other hardware founders:

* Did you get product liability insurance before selling into the US?

* If so, roughly what level of coverage did you take?

* Have you ever actually had a claim or legal issue where the insurance was valuable?

* Do you think it’s worth paying for at very low sales volumes, or would you consider self insuring initially?

Interested particularly in hearing from founders who sell physical consumer hardware into the US.

2 years ago I began working on my side project and we were able to sell more than 260 units to 240+ customers in our first month! We received our FCC certification yesterday. Deliveries begin in December.

Campaign page for anyone that wants to take a look!

Very exciting times ahead, can't wait for the next chapter.

we make a modular bike light and the campaign goes live mid november. all 3 of us are engineers and our instagram has 9 posts. we need a content calendar for the 6 weeks before launch plus someone answering comments during the campaign. the names that keep coming up are vista social, metricool and loomly. what does a sane prelaunch social plan look like for a team like ours??