Well, here is today's idiot update. 
Following what Mr Stirling had posted yesterday, I created a pulley, called it Pulley 1 set my Minimum and Maximum Motor speeds as 500 and 23,00 RPM respectively. I could then vary the Motor speeds from the MDI interface, i.e. M3 followed by S500 would run the Motor at about 1,200 RPM where as S3000 would peak the motor at maximum RPM

Wonderful I thought, so then I found the Spindle Calibration Routine which I thought would put my Motor RPM somewhere nearer the on screen speed. I ran the routine which started the Motor running about 800RPM and gradually as the on screen RPM increased, and so did the Motor - All going great I thought.

When it finished the routine, it reported something to the effect that the Spindle Motor was now calibrated and all was fine... GREAT... 

How wrong I was, the spindle speed on the Mach3 Main panel reads -1 (Minus 1) and the motor revs its little @$$ off whenever I switch it on without any control over the speed, then the RFI from the Motor Spitting and F@rting kills my Mouse..... 

To top it all, I have just had my once per day two line four word e-mail form the little yellow people. Yesterday I asked them for the Mach3 Settings for the Spindle Motor, as there is no mention in their Chinglish Manual about it. Their reply was, "Dear friend, ‘Our specification:3040Z and 6040, Thank you so much!, Have a Nice day" Whatever that is supposed to mean……

I just checked the PWM output by Mach and it's relationship to what is entered in config pulleys and all is as it should be - spot on. I'd start to wonder about the quality/linearity of your kit in how good it is at converting the PWM into the control voltage needed by your spindle controller. Also - do you actually have an index pulse from your spindle? I haven't seen you mention one if you have. Without an index pulse I can't see how Mach can calibrate the spindle.

Maybe this is worth a read http://www.cjh.com.au/PWM%20Spindle%20Control%20using%20Mach3.pdf

Ian

And I think you need to smooth the PWM output with an RC filter...

Well another day (or two and I am very pleased to report that my Machine is now up and fully operational  I would really like to thank all you Guys who have given me the time to reply with hints, tips and encouragement to resolve some of the mountainous problems I have had to resolve with a piece of kit in many years.

To report back on what I found to be the cure for my runaway delinquent Spindle Motor.
Firstly the RFI problem had to be addressed. That with the associated ‘Shock’ when for no apparent reason the Spindle Motor would instantly start up and rev its testicles off was rectified. Remembering back to my early days when as a TV Engineer to test the Line Output Stage, we would disconnect the Line Output Transformer and replace it with a 60W incandescent light bulb.
This would put sufficient load onto the drive circuit to simulate a load and allow you to determine if the line was oscillating at 15,625Hz  This did the trick as not only could I see any changes and variations in the Motor Speed Controller, it no longer killed my rodent  which was making progress impossible.
To shorten this I went back over my settings and lo and behold this beast does not respond to Pulse Width Modulation (PWM) but prefers to work quite happily with Step/Dir signalling.


I can now control my Spindle Motor Speed infinitely from 800RPM to 20,000RPM with the maximum deviation of about 400RPM from the onscreen settings (DRO?? if that is the right terminology) to the actual Motor Speed when I test with my Tachometer. 

 The Rodent Problem has gone also, probably with the absence of the PWM in the Spindle Motor Supply…..   
   
I have attached a screenshot of my Spindle Setup for anyone finding themselves in the same dilemma.

Once again THANK YOU ALL for your help, hints, tips and encouragement, and finally sorry for making this such a lengthy post.

p.s. Watch out for the next Newbie Stupid Posting (or beware!)     

Good to see you got there in the end, hopefully things will run a bit more smoothly from now on

Hood

nice one - good you got it sorted and thanks for coming back and posting the solution.

Ian