After we have opened the knitting machine and figured out all the contacts of electronics, we were able to start designing a circuit for controlling the knitting machine from Arduino.
We have designed circuit in Fritzing in order to produce PCBs.
Instructions for printing PCBs we found here: http://www.riccibitti.com/pcb/
Here is our first results after transferring circuit printed with laser printer on a magazine sheet with a hot iron:
Obviously, we have had not so good quality copper shield and maybe ironed the board for too long time. But we could use the other half that was fine.
Next step: acid!
PS. if not all print had transferred to copper, use permanent market for corrections.
When acid has eaten all the copper, except needed connections, the board can be taken out from the acid and cleaned with aceton. And voila, it was ready:
Now we had to make holes that electronic components could be placed. After completing this hard task, we have discovered that we shouldn’t have used MIRRORED schema, but just BOTTOM. So we had to repeat all the process once again. And finally we got this: