Well I hope the educated Mach3 gurus can put light on ways to accomplish my desire.  I bought the MP2/ZTO from Texas Micro and am working with the developer's assistance.  The ZTO touches off  and resets the Z=0 at the table base.  The problem is that I am machining 3d items which require multiple tool paths using different endmills.  After the first toolpath many times all the surface references on the material have been removed and can't easily be zeroed to the material surface with the new bit.  I know you say I can zero off the table and I know this, but all of my prepurchased 3D models with toolpaths already created were zeroed on the material surface.  I could just make a habit of redoing all the toolpaths to zero on the table surface but hope there is a way to write a macro which will allow a tool touch off to table surface then have an input screen to correct Z=0 to the material thickness.  It would seem that this would be possible with all the user configurations that Mach3 can do.  Has anyone already done this or can guide us to possible ways to accomplish this?

Thanks

Jerre

There have been quite a few macros posted here for tool height setting, most have a plate thickness in the macro for the touch off plate you use, you could set that to a negative value equal to the thickness of your stock and it should do what you want.
Have a search for auto tool zero and you should get some hits.
Hood

Are you using the tool database and tool offsets?  Each tool should be set up in the database with an offset relative to a referencing tool or probe.  I used a 1/2" round bar with a point machined on one end for referencing.  Once the machine is referenced using the referencing tool, after a tool change Mach applies the offsets for that tool.  I never zeroed the Z with an actual cutting tool, always the referencing tool. 

I sold the router a couple years ago and don't have the tool change macros that I used anymore, but I think it's all in the Mach manual.  Look at the G-code section for tool change and tool offset code.