I'am the new kid on the block and need lot's of help. I have the xylotec 4 axis system and it works like a dream, no problems at all.
however I would like to be able to turn my 110v AC router on and off thru Mac3 .   Can it be done with the xylotec system?.  If so how?.
Power relays?  thanks for anyones help.

I think Xylotec has some generic I/O, just on your Ports and pins, assign Output 1, 2..or what ever to your M3 under spindle control, and hook that output to your on relay on your spindle.

I would like this feature but am out of my depth.  I would be grateful for someone to recommend the hardware I need for this.  Thank you.

It depends on the type of output you have. Check if you have an open-collector one that can sink 10..20mA. If that is the case, then just hook up an optoisolated solid-state relay. Ie solething like: http://www.davis.com/catalog/product_view.asp?sku=6847435&pfx=

Hook the positive control terminal to +5V and the negative to the open collector one. I assume that you get a relay that can be controlled by 5V.

OTOH. If you are the least bit unsure to work with mains potentials, then ask someone to help you...