Just an update, i will post the picture later of the settings and the electronics inside the box
Strange thing just happend that may help us solve this.  
As  i said before, the spindle runs when you use the claibrator in mach3,    it sounds fine getting up to 8000 revs,  then from 8000-23500   it sounds like its reving up and down slightly but doenst seem to speed up much.  22500 - 24000 it speeds up a bit    I will post a picture of the calculated curve latter.
Here was the odd bit.   Run a bit of code,  it seems to run ok at  one end of the table ( start the spindle,  but not at the other end of the board, ( wont start the spindle )).  
We then run the same code in the middle of these two points,  and as soon as it travels past a certan point on the board, the spindle makes a funny noise but keeps running,  as soon as it clears that point.  the funny noise stops.  
So, i then lifted the cable that are in the cable arm, and the noise does not come on.  we tested this a few times with teh gcode was running.   
I suspect that maybe there is some interfarence in the cable,   we are going to re-check all these later on, re-rout the cable  make sure there is no interfarence.  
The calculated curve still looks odd though,  i will post picture later.