retrofitting an older CNC

After using CNC mills both at a friends shop, and as school, I decided I just had to have a machine of my own. After saving for the better part of a year, I just bought a CNC Shizuoka mill with a Dynapath Delta 20 controller (pics at: www.cyclegarage.net/mill). I�m not sure if the controller is any good. It seems to work but I�m getting a fault on the Z axis. I bought the machine figuring that the controler wasn�t working, and had planed to replace it (of course only knowing enough to be a danger to myself and others :-) ). It seems retrofit controller systems by Centroid, and Anilam etc. are way too expensive for my current budget. I was hoping to use as much of the existing hardware (servos, servo amps and electronics) as possible, and just use a PC as the controller. The mill is currently fitted with Baldor permanent magnet servos. The book for the servo drives (the only documentation I have) mentions that the drives are looking for PWM signals from the controller. I know that
one could probably write a book in response to my questions, but I just need a general bit of clarification.



1. Systems that use gecko drives don�t have absolute feed back? That is, the computer sends motion signals (step and direction) to the drive but has no way of knowing if the servo is in the position it is supposed to be in? How does this compare to the positional accuracy as compared to the current system?



2. Does the fact that mach 1 uses step and direction commands mean that it can�t be used with the existing servo boards in this machine? If not what controller software (EMC?) would work?



3. How do I interface it with the existing hardware? If the servo amps don�t except step and direction signals, then I assume that a simple breakout board such as those used with gecko systems won�t work. Likewise anyone have suggestions as to what will?



4. These servos are rated a 120v and 10A (continuous) 39A (peak). It is my understanding that these can be used with gecko 320 drives, but will not achieve their maximum rated torque or reach their 2500RPM max rated speed. Is this correct? Will the tachometer need to be replaced with encoders in order work with this system? Rutex drives seem a better choice, true?



Lastly. How hard would it be to include the stepper motor controlled spindle speed, and tach into the new controller? Could this be done by defining it as say a 4th axis?



I�ve been searching and reading as much as I can, and have royally succeeded in confusing myself. Any links and information I get I plan on including on a page on my web site covering everything I do to get this machine running. I hope to document everything I go through, as other who have done so are what inspired me to try this crazy stunt. >:-)



Thanks in advance for your help.



Peter-

pdh@...

(remove knowspam to reply)





---------------------------------
Do you Yahoo!?
The New Yahoo! Shopping - with improved product search

[Non-text portions of this message have been removed]