Desktop PCB Milling
Torsten Schoofs has been producing circuit boards for decades. While he initially created them using the etching process, he has now dedicated himself to isolation milling with his two STEPCRAFT CNC systems.
His approach has always involved initially drawing the layout, for example, in the PCB layout program ‘Sprint Layout,’ printing it on transparent film, and transferring it onto the blank PCB. The next steps involved exposure, development, and etching. However, for the last two steps, the trained industrial electronics technician was always forced to use harmful and sometimes foul-smelling chemicals. Another significant drawback for him was that “everything had to work one hundred percent in sequence, and only then do you have the blank PCB in your hands. The entire process of drilling the holes and cutting is still pending.” Especially the drilling part is pure manual labor, as 300-400 holes in PCB creation are not uncommon. Placing these holes exactly in rows during manual drilling is not only difficult but also very time-consuming. It’s self-evident that with such a labor-intensive method, trial and error take up a lot of time. “I always had trouble etching PCBs properly because I wanted them to be perfect.
Even before the turn of the millennium, Torsten Schoofs discovered CNC machines for milling PCBs in a catalog. Although these were geared towards professional users in terms of price and features, the desire to manufacture PCBs using this new technology was born in the mind of the electronics enthusiast. Over the next decade, the internet became widely accessible, enriched with a wealth of information that Torsten Schoofs utilized to delve into the topic of CNC. In 2013, together with an acquaintance, he visited the Intermodellbau trade fair with the clear intention of acquiring a milling machine for hobby use. “At that time, the desire to create PCBs in this way was certainly already 15 years old,” he notes. At the fair, he also discovered the STEPCRAFT CNC systems. “I saw the machine and just said, ‘That’s it!'” recalls the hobbyist. Since the prices were also very interesting for him, he opted for the STEPCRAFT D.420, the company’s largest system at the time. He not only wanted to mill PCBs but also be able to work on plastic parts for enclosures and wood.
The assembly was done together with a friend who is an industrial mechanic. “It’s not assembly line work. Ideally, you should also enjoy assembly and have a bit of a sense for mechanics,” explains Torsten Schoofs. His new approach to PCB manufacturing now only had drawing in the layout program in common with the previous etching process. From now on, the process involved exporting the file in PLT format and importing it into the machine control software WinPC-NC. Quickly attaching the blank with double-sided tape to a small MDF board, which is then fixed on the machine table, the process can be started. Initially, the machine mills the traces, followed by drilling the holes, before cutting the PCB out of the blank. “I’m not shy with the feeds, and the STEPCRAFT drills one hole after another. It’s amazing,” the electronics enthusiast enthuses, explaining further: “The most fascinating thing is that the PCB comes out of the machine completely finished. Just clean it up and spray a bit of solder resist – done!” Now, special shapes like a handle or semi-circular form are possible. The entire process, from drawing to the finished piece, takes about three hours for a single PCB. “But the next one is ready in 10 minutes,” says Torsten Schoofs. This reproducibility is particularly important to him: “You can build a PCB, and if you see that something is not right or doesn’t fit, you can just redraw it and send it through the milling machine again. If I had to etch again or have a PCB made, it would cost a lot of time and money.” To test circuits and see which components are needed and how they work together, he initially creates these circuits on a breadboard. While components are usually mounted directly on the breadboard, this can be a tricky task where the legs of the components quickly bend. To address this, the hobbyist created adapter boards. He then adds information about the various connections. This not only makes his work easier but also has another significant advantage for Torsten Schoofs: “I can make electronics more understandable for children because they can handle it better.
Projects like these convinced the trained industrial electronics technician so much that, just a year later, at the Intermodellbau trade fair in 2014, he decided to get his second STEPCRAFT machine. He describes the STEPCRAFT D.300 as his ‘desktop machine,’ which has a permanent place in his office and is specifically used for creating PCBs. This includes the DIY construction of his home automation system. ‘I would like to control various functions in my house very flexibly. This includes lighting, blinds, ventilation, and intrusion detection. To control this extremely flexibly, you don’t actually go for fixed wiring but for a programmable bus system,’ says Torsten Schoofs. While such a system is available for purchase, it is very expensive. Additionally, the prospect of building it himself was appealing, as it not only makes him more independent but also allows for the gradual installation of the system. The hobbyist initially created a prototype of a PCB, which he optimized until it fit well into the protective plastic housing. Of the 80 PCBs he needs for his home automation system, he has already been able to create nearly 30. ‘The microcontroller on the board is programmed to send a signal to the bus, for example, ‘The light switch was pressed.’ All of this goes to a central unit, and it knows that if the light switch is pressed in the back, then I have to turn on the lamp with a completely different board, for example. The central unit then sends a signal there again. The advantage here is that the central unit is freely programmable,’ explains the hobbyist. This way, adjustments are still possible at a later time.
After six months of construction, there is now a four-week phase in which Torsten Schoofs is designing and testing the bus system at his home, involving six participants. Successfully passing the test, the installation is set to take place from December. Until then, Torsten Schoofs is looking forward to the use of his new tool changer. With this, he will manufacture the remaining 50 PCBs for his home automation system. ‘I come back after ten minutes, and the PCB is ready. What more could you want?’ he enthuses, concluding: ‘I would definitely choose STEPCRAFT again.