Re: [CAD_CAM_EDM_DRO] How to choose?; was "parallel port finally obsolete?"

scyvt wrote:

>
> There are 5 or 6 machines here awaiting CNC conversion. Every time I think that I may have a handle on product selection, some new offering comes along, muddies the waters, and I postpone the project, supposing that clarity will surely come along when I discover the elusive key.
>

Well, I have been using EMC since 1998. I started a Bridgeport mill
retrofit
with an Allen-Bradley CNC control from the late '70s, but it was unreliable.
I learned the elements of CNC on that system, though.

I was the 2nd user outside NIST of EMC, and made connectors so I could
go back and forth between EMC and the A-B control. After bugging NIST
a couple times to fix some rough spots in usability, I disconnected the A-B
for the last time. I used a Servo-to-Go ISA plug in card, and it had a
number
of smaller problems, but generally worked OK. EMC was great.

I brought out a number of products to interface analog servos, steppers and
digital servos through the parallel port, using that port as a
real-time, non-buffered
communication channel to the external hardware. Communication is direct
this way, there is less than a 1 us delay between the CPU and the external
hardware. The total servo cycle process is usually completed in under
100 us on a typical PC.

Just like buying a new computer, there will always be a new model coming
out every week. DON'T buy the newest offering in computers or cars,
let them mature and let others find the inevitable bugs.

I've been using EMC since 1998, and using EMC2 since about 2007, as the
Axis GUI was too great an improvement to miss. I've never had a crash
or major malfunction of of EMC in all that time!

So, your choice of either waiting, perhaps forever, for a CNC system to
come out
using your favorite computer and communications channel, or pick one of the
available packages and obtain the computer and motor drives to use it.
A very limited computer to run LinuxCNC can be had for a bit over $100,
or a used machine on eBay for even less. Cast-off computers might be
found in the dump.

Jon