Re: [CAD_CAM_EDM_DRO] servo or stepper?

> So would there be a way to control the amount of rotation in relation to
> linear movement? Say for one application I want one rev per inch and then
> maybe change to one rev in 4 inches. How would I do that?

If you want it to be easily reconfigured, it does make sense to put a
computer in the loop. Now you need an encoder interface card and a
program that watches the encoder, calculates the correct position of
the slave axis, and commands any movement needed to get there. With
steppers and slow rates of movement, this can be done in basic. But
for higher rates, or if a servo loop must be closed, you need a c or
assembly language program running in an environment where there is no
way for an operating system to delay its ability to respond quickly.
One way to do that is to write a program which can be started from
real ms-dos, given the divisor parameter and then proceedes to crash
the computer by making it cease to do anything but slave the motor to
the encoder - you reboot the computer to reconfigure it. Other ways
are to learn to write hard realtime code in an environment such as
rtlinux, or to use a dedicated microcontrollor such as a PIC or an 8051.

Another approach is a motion control board with its own processor. I
believe the PMAC series from delta tau can do this kind of electronic
gearing - you can set it up with commands from a host computer (the
board can be put in the computer or connected via a serial port) and
then it does the work all on its own.

Chris Stratton