On Thu, 21 Jun 2018 23:06:55 -0500, Jon Elson
wrote:

Stephen B. wrote:

I remember there was discussion here about replacing CNC controls, but
could not find it, and what controls were liked.

We have an old Bridgeport in reasonably good condition that has an
ancient CNC system that needs to be replaced. What systems should we
look at?
In the hobby-level arena there is LinuxCNC and Mach(x). There have been
lots of flame wars over this.

In the professional level, there are things like Centroid, Ajax and Acorn.
(All these are apparently by the same company.) The Acorn uses a Beagle
Bone type computer, and is amazingly inexpensive for a commercial control.

I have 2 mills running LinuxCNC here.

Jon
Boy Jon, that Acorn really is cheap. If I had to replace the servo
amps in a machine I would for sure look at the Acorn option.
For Stephen: The Acorn puts out step and direction signals. Stepper
motor drivers accept step and direction commands. But there are also
several servo amps available for not much money, Gecko Drive being one
I am familiar with and use, that also use step and direction commands
for controlling the servo amp. This means that the less expensive
step and direction control can be used to control servo motors. If
your mill has stepper motors then i suggest you look into upgrading to
a closed loop servo system. The servo system will allow much faster
rapids as well as faster and more accurate machining of contours. I
messed around with stepper motors when I first built CNC positioners
but quickly swtiched to servo motors when step and direction input
servo amps became available for such little money. I think you can get
one now for about $120.00 that will drive servo motors at 80 volts and
20 amps. It may even be to your advantage to get an Acorn and replace
the existing servo amps if your machine has servo motors.
Eric