E stop switch with router install guide

Hi guys,

Being a cnc newbie means I make all kinds of mistakes with work holding and clamps etc. One thing I really needed was an estop button. So I looked around on here and couldn’t find much on an estop switch on the newer revisioned boards.

So I pieced together a few different threads and made an estop button that’s taps into the feedhold pins on my board. But this didn’t solve my router still creating carnage. And probably being the most dangerous part of the operation.

So I then looked at router control in the forum. And found most people have used the pwm pins and a solid state relay for a great result.

When googling estop switches I noticed they all have 2 sets of contacts. 1st normally open and the 2nd normally closed.

This works really well for what I wanted to do as the feed hold pins need the normally open contacts. Then I used the normally closed side for the pwm positive supply to my solid state relay.

So now when I’ve made a mistake I hammer the little estop button and my shapeoko stops under feedhold and my router stops tearing through something it’s not meant to be cutting. Once I have adjusted the clamps etc I reset the estop button and press play in carbide motion and it’s on its merry way again. No new setup or re homing etc.

Hope this comes in handy for someone else.

I have pictures if my description is no good

Cheers Jason.


I’ve never heard of anyone using the PWM signal for “Router Enable”. The PWM signal is used, of course, for VFD speed control or laser power modulation. If you wanted to control a “Router Enable” relay via the NC side of an e-stop button, it would likely be better to just use a 5V pin.

As for me, I went with a little external supply connected through my e-stop’s NC side, leaving the router side completely isolated from the Carbide Controller FEED_HOLD side. I figured the potential benefits of total isolation outweighed the additional part. (I do have a laser module on my machine, so I certainly would not have used the PWM pin, of course.)

For completeness, this is how I set it all up:

Hi Clayjar.

Well i am a plumber so… it may not be the best way to start and stop my router with carbide motion.

But i did follow this excellent spindle control example on the wiki.


All i added to the already very thorough guide was the e stop using both sets of contacts.


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