Instead of re-inventing the wheel just send $20 to cncwoodworker.com and save yourself some grief.  He has already worked out the particulars.  You will spend more than that in lost time and effort.

Bob

OK, things are coming together now...

So whats the purpose of setting the old tool again?

If (oldTool <>  tool) Then
SetOEMDRO(1212,tool)

I assume this depends on the job your running... and assuming you want the old tool settings restored?

This line I believe zero's Z to the touch plate.

Code "G0 Z" &ZProbePos

What determines the speed at which it does it?

Code "G31Z-5 F" &ProbeFeed

This line I believe zero's Z to the touch plate.

No. It moves back to the touch position, in case the probe has overshot the touch position.

What determines the speed at which it does it?

Whatever the ProbeFeed variable is set to.

Some clarification on the workings of touch-off routine.  Initially toughing off with movable plate establishes the offset between the z-zero and the fixed touch plate.  This is done during initial setup.  On subsequent tool changes the new tool zeros to the fixed touch plate only since the offset is already established.  Then the spindle starts and you are off to the races with the new tool.  IMHO this routine should be written into ATC tool changes as well in case the bit were not set into the tool holder correctly.

Bob

OK that makes more sense Gerry this is the tool probe...

Code "G90 G31 Z" &DownStroke &" F" &DownFeedRate 'probing move
While IsMoving() 'wait while it happens
Wend
ZProbePos = GetVar(2002) 'get the axact point the probe was hit
If Abs(ZprobePos) <= Abs(DownStroke)-0.1 Then 'Check if the probe has been found

I don't see the 1200,1201 and 1202 on the DRO wiki, are these established somewhere?

  'Get the tool change pos from the settings page
  ChangeX = GetOEMDRO(1200)
  ChangeY = GetOEMDRO(1201)
  ChangeZ = GetOEMDRO(1202)

Bob, I realize there is always someone willing to do something for money but it kind of the defeats the purpose of building your own cnc. I'll keep your suggestion in mind in case I can't manage to solve the puzzle, thanks.

I don't see the 1200,1201 and 1202 on the DRO wiki, are these established somewhere?

DRO's over 1000 are User DRO's, which are defined when they are added to the screen. These 3 are the toolchange position DRO's on the settings page.

So, MachScreen shows 1200,1201 and 1202 as User defined on the overview and are located on page 6 on the 1024.set.

When I go to view design on page 6 I see the "Tool Change Location" boxes but when I click on them it doesn't show the code just a box opens with DRO "139" not with 1200,1201 and 1202 DRO's, so I'm a little confused.

I thought they would have the 1200,1201 and 1202 in them?

I don't use Machscreen, but I checked in Screen4, and they are listed as 1200, 1201 and 1202.