Now that I have my machine doing what I want it to do I have this question. How can I accurately change tools bits on a router? I want to make one or two changes on a piece. I mean to get the tool bits the same hieght from part zero. I need a simple cost free application, something a gnome can use without thinking too much. Any suggestions will be helpfull. Thanks

I guess it comes down to the accuracy you require. For doing 2.5 D cutting, you can just do it by eye.
You can also have an area on your machine where there is an aluminium block in the corner of a known height. You can make connect a small current to the cutting tip and the alum block, when you drive the Z down it hits the block and connects the circuit. This can be done automatically using a macro to then also reset the DRO to the correct height.
I use the eye method myself, so I cant tell you all the setup details. But I know the electrical method can be done.

Oh you can also just use a set microswich in the table so the tool hits it and then does the same as previously described.

Why not set them with a vernier caliper from the end of the spindle, NOT the colllet.

Graham.