Re: retrofitting an older CNC

Peter,

IMO, it would be a very big mistake to retrofit the Delta 20 contol
with a PC type. That would be a major step backwards in performance
and features. The controls you mention don't begin to compare with
what you have.

What you have now is one of the best controls ever made. It has an
assortment of features as standard that cost a small fortune on
other commercial controllers.

Fixing it shouldn't be a problem. Most likely it's just the drive
that needs to be tuned. If you have Servo Dynamics drives they'll
supply you with the instructions.

If for some reason you decide you want to replace the control and
drives I'll buy them.

Doug









--- In CAD_CAM_EDM_DRO@yahoogroups.com, no falloff <nofalloff@y...>
wrote:

>
> 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@k...
>
> (remove knowspam to reply)
>
>
>
>
>
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