Re: [CAD_CAM_EDM_DRO] canibalising old printers

cadcamcenter@... wrote:

> Hi,
>
> Just wondering if there are any motor driver board that accept step
> and direction signals that can be cannibalised for lightweight CNC
> work.

Driver board? Many companies (Gecko, MicroKinetics, etc.) make
step/dir driver units. ome are boards, some are packaged modules.

By cannibalized, do you mean getting them out of old computer printers?
You won't find a printer that has a complete stepper driver board that
can simply be unplugged. There are stepper driver chips in there, you
could unsolder them and try to build a stepper driver from that, but
unless you are pretty experienced electronically, I wouldn't recommend
it. Many of these chips have proprietary part numbers on them, so you
wouldn't be able to look them up, anyway.

> I understand that most printers are controlled using HPGL rather than
> G-code.

Printers? HPGL is the command code that is used for graphics on
HP laser printers. They do not move anything to draw lines, they break
it down into pixels in a computer memory and then draw it line by line,
like a TV screen.

> I understand also that some controller accept steps and
> direction signal and others phase (whatever does this mean?).

Step and direction means there are 2 signals. One tells the driver which
direction to move, and the other has pulses which move the motor one
step for each pulse, in the direction specified by the direction signal.

Phase inputs are signals that specify which way the current is to go in
the motor windings. You can have 2, 4 or more phase inputs, depending
on driver design and motor type.

> Are
> these two (language and controller) related or independent, and how
> so?

The "language" is a higher level of abstraction that specifies movement
in some rational units (inches or mm) rather than steps, and specifies
complete movements, including speed, without reference to steps.
The language is interpreted by a CNC controller, which can be a program
run on a PC computer. The language and "controller" are intimately
related. The language is the input the controller expects.

Now, the language and controller are NOT intimately related to the
motor driver. The controller software needs to know maximum
accleration and speed for a particular stepper driver, but little else
(other than steps / inch).

Jon