The relays I used as “emergency stop” relays had some trouble with burned and sticky contacts. I replaced it with a bigger 40A relays but that also got the same problems (probably because of the inrush currents). Then I decided to make a solid-state relays with 4 TIP2955 transistors.
To drive this solid state relays and provide 12V for the fan in the back of the case I made a 12V power supply. On the cnc there will be led lighting, and that is also powered by this power supply.
The traces on the underside of the ssr are reinforced with wire so it can handle more current.
I also painted the top of the case.