Re: Comments about old CNC controls
Posted by
Jon Elson
on 2000-05-09 10:56:21 UTC
Andrew Werby wrote:
Allen-Bradley
7320, one of the most sophisticated CNC controls of its time. It is
from the late
1970's, proprietary 16-bit minicomputer, racks of I/O cards, solid state
memory
up to 64 K Bytes. I managed to get it running, but it was not reliable,
and thankfully,
EMC got to be usable just about the time I was getting worried about the
downtime
on the AB. But, aside from that, it had a 100 Hz servo update rate,
which caused it to
be a very sluggish control. Probably no problem on a 50-ton bed mill,
but just
too slow for a Bridgeport. Also, the block processing time was real
slow, so that
some engraving work I did that consisted of thousands of tiny vectors
took over
an hour to engrave two words on a piece of plastic. Well, at least it
seemed like
over an hour, certainly way over a minute for each letter!
Now, I'm an Electrical Engineer who grew up fiddling with and fixing
16-bit minis
and related gear, and I did have the schematics, theory, etc. for the
AB. Still,
it was a pain. Maybe your Centurion IV control is more reliable, but if
it is from
the same vintage, I doubt it.
So, you might want to think carefully about whether the Centurion will
do what
you want to do, and remain operational. If you want to replace it, you
could
keep your servo amps, and switch over to using EMC to run the servo
motors.
That is basically what I did, although I had to make my own servo amps,
as my
control didn't come with them. If the Centurion/Ramco has shaft
encoders or
linear encoders for position feedback, you would be pretty well set for
the
upgrade to EMC with either the Servo-to-Go card or the flexible
parallel-port
interface I am designing now. If the machine has resolvers or
Inductosyns, then
you would have an additional conversion to make.
Just something to think about, before spending big money on a DNC setup.
Jon
> Re: PROJECTS STILL ON THE BURNER?I thought I should add a bit more commentary about this. I got an old
>
> It now appears I can get my Beast (the 1984 Leadwell-Ramco) of a
> milling
> machine to accept drip-feed input through its RS-232 port. I tracked
> down
> the people who made the old Centurion IV control (they are called
> Milltronics now, and are located in the Minneapolis area) ,
Allen-Bradley
7320, one of the most sophisticated CNC controls of its time. It is
from the late
1970's, proprietary 16-bit minicomputer, racks of I/O cards, solid state
memory
up to 64 K Bytes. I managed to get it running, but it was not reliable,
and thankfully,
EMC got to be usable just about the time I was getting worried about the
downtime
on the AB. But, aside from that, it had a 100 Hz servo update rate,
which caused it to
be a very sluggish control. Probably no problem on a 50-ton bed mill,
but just
too slow for a Bridgeport. Also, the block processing time was real
slow, so that
some engraving work I did that consisted of thousands of tiny vectors
took over
an hour to engrave two words on a piece of plastic. Well, at least it
seemed like
over an hour, certainly way over a minute for each letter!
Now, I'm an Electrical Engineer who grew up fiddling with and fixing
16-bit minis
and related gear, and I did have the schematics, theory, etc. for the
AB. Still,
it was a pain. Maybe your Centurion IV control is more reliable, but if
it is from
the same vintage, I doubt it.
So, you might want to think carefully about whether the Centurion will
do what
you want to do, and remain operational. If you want to replace it, you
could
keep your servo amps, and switch over to using EMC to run the servo
motors.
That is basically what I did, although I had to make my own servo amps,
as my
control didn't come with them. If the Centurion/Ramco has shaft
encoders or
linear encoders for position feedback, you would be pretty well set for
the
upgrade to EMC with either the Servo-to-Go card or the flexible
parallel-port
interface I am designing now. If the machine has resolvers or
Inductosyns, then
you would have an additional conversion to make.
Just something to think about, before spending big money on a DNC setup.
Jon