Re: [CAD_CAM_EDM_DRO] Re: Pico board

Ken Jenkins wrote:

> > Well, I have sent the PC board out to be fabricated for my $200
> > 4-axis step/direction with or without encoders board that connects
> > to the parallel port. This also has 16 digital inputs and 8 locations
> > on the board for solid state relays.
> >
> > See http://pico-systems.com/univstep.html for more info.
> >
> > Jon
>
> Hey Jon, I really like the looks of your board and it's very obvious
> a lot of thought has gone into making sure all the "goodies" are
> there. Could you describe (briefly) what the rest of the pieces of
> a full system with your board at the center might look like i.e.
> examples of the software front end to this (I'm assuming it's
> set up to run ideally with EMC since I don't know of other software
> that has the ability to read quadrature encoders back and drive
> s&d out (I could be wrong here ... probably am ...). Also, from the
> output side, what sits between your phase outputs and the motors
> themselves, i.e. how do you get your phase signals "beefy" so they
> can move the motors. I know there's a power supply matched to the
> motors current and voltage requirement ... what else

(Bill, I hope this isn't getting too "off topic" or sales related.)

Yes, the software is EMC, although I have published the specs for
my servo board set, and will shortly add the specs for this board
to my web pages. I'm hoping some other products will provide
drivers for these boards.

For a simple 3-axis milling system for a machine like a Sherline,
Taig, Grizzly, etc., this is what you need. 100 MHz Pentium computer
with 32 Mb of memory and 1 Gb hard drive is the minimum system,
roughly. (Note that even a 100 MHz Pentium classic has plenty of
CPU power with this board, as the board creates the step pulses,
not the CPU.) Next, 3 stepper drivers and suitable power supplies of your
choice. Gecko drives are nice, and there are many other types
available. Any stepper driver which takes step and direction inputs
or full-step phase waveforms should work fine. The prototype of this
concept was run at the 2001 NAMES show last April with a MicroKinetics
driver on a Sherline, and we were getting 20 IPM rapid speeds, which
amazed some people, as most other programs couldn't go over 10 IPM
before the motors lost steps.

This is the minimum configuration. If you want closed loop, you can add
any make of quadrature encoder that has TTL-compatible (ie. 0 and
+5 V) outputs. Limit and home switches can also be wired in with no
external hardware, and the home switch resolution can be refined if the
encoders have an index output.

You can control the spindle motor with a solid state relay, and also
shut off the stepper drivers or step/servo drivers with another, for an
Emergency Stop function. (This would be a good idea if using Gecko
Servo drives or similar units.) Another solid state relay can be used for
coolant or whatever you might imagine (plasma torch, EDM power, laser, etc.)

The solid state relays are not provided, as you may want different models.
They cost less than US $8.00 each from Digi-Key. They just plug into
sockets on the board.

The board can be mounted on a DIN rail with parts from Phoenix Contact.
That is in their UM 108 series.

The board comes with a "wall wart" power supply, and generates an isolated
+5 V supply internally to power the linit and home switches. It also
provides
non-isolated +5V to power the encoders.

Jon