Re: Re: Old CNC controls

>
> From: Jon Elson <jmelson@...>
>
>
>
> "D.F.S." wrote:
>
> > From: D.F.S. <dfs@...>
> >
> >
> > > From: Jon Elson <jmelson@...>
> > >
> > > >"D.F.S." wrote:
> > >
> > > > if it
> > > > doesn't start correctly just one time, it will burn up.
> > >
> > > No, it will blow the breaker, pronto! It is VERY hard to burn up a
> > 15
> > > Hp motor!
> >
> > In all honesty, I'm a lot more concerned about toasting something
> > in the controller.
>
> Well, most controller manufacturers void their warranties if a rotary
> phase converter

This is one reason I have not got things connected yet.
I have no warranty, but am a bit worried, for the same reasons, a mfgr.
may be about damage.

I don't think I'm going to use the controller at all now.

IF I can get a good feeling that EMC will do what I want, I'll just go
that route.

The only use withing the lathe itself for 3 phase power is the motor
itself. It is a 2 speed motor with a 2 speed transmission of some sort.
I have 4 speeds, I'd like a variable speed setup of some sort.
I have a 7.5 Hp DC motor, but am a bit concerned about keeping a
constant speed under a variable load, and how that would screw up things
like threading, no pun intended.

Maybe a variable speed transmission would be a good project.

In any event, by replacing the controller, I have gone to either
needing 3 phase for one motor only, or maybe for nothing if I replace
the motor. That is a lot more doable, and less risky IMHO.

I hear even the DC servos run better run from a REAL 3 phase power
supply, I wonder if it is even worth the trouble with a Pseudo 3 Phase
power source.

> I tried to hook up a 17 KVA
> motor-generator set at a friend's home, and we had all manner of
> problems.

That was another option I considered, I have an actual 3 phase generator.

> How heavy a
> 240 V service do you have? If less than 200 A, you are in big trouble!

That could be a problem, I think the feed to the shop is only 100.

> > My controller appears very sensitive to the correct phase rotation.
>
> How do you know that? Is it in the manuals?

I don't have any manuals, another reason to not use the controller.
All I'm going by are the stern warnings and diagrams inside the cabinet.

> > It is old, probably unrepairable, and I have no documentation on it.
> >
> > Toast one 20 year old IC, and the whole thing is reduced to junk.
>
> Well, given good documentation, most of this old stuff is repairable.
> Without schematics, it can be beastly to fix anything, new or old.
>
> > That fear, is a large reason to move to a EMC, as much or more
> > that the added functionality.
>
> Well, my experiences with my Allen-Bradley 7320 were that the older gear
> (20 years old,
> in my case) can be pretty unreliable. Not just power semiconductors,
> but connectors,
> switches, memory chips, video monitors, and always back to flakey
> connectors, will
> cause you headaches.

Mine was built in '79.

Old for electronics.

Pretty modern as to a lot of the mechanics the way I see it.

I'd like to keep the good, and replace the old and unreliable.

One real advantage, is that everything is already there.
This thing was designed and built for computer control, it already
has all the limit and sense switches, motors to run all the axis
and encoders, I have not identified them yet, but they are there.

>I was glad to move to EMC at that point.

How have you set up your system?

What kind of motors are does your "Mill?" use?

How are you driving them?


Marc