Hi Tony

If I were you I would implement a E-Stop circuit from the word go, when you are new to CNC which I assume you are, you will inevitably make mistakes if you have a nice BIG red e-stop button you can hit in the blink of an eye it will pay dividends in the long run.

Do not under estimate the power of these machines your cutting tool will cut through skin and bone with ease.

I have used a Pilz safety relay on my machine which kills everything safely these are fairly easy to wire up but not cheap!

Regards

Andy

This would do the trick (eBay No:- 281014635581) I could give you a diagram to help fit it.