Re: [CAD_CAM_EDM_DRO] re:Re: lathe arcs

Dear Carey,
I didn't follow much your problem. What kind of CNC do you have?
I had grave similar problems with 2 GE 550 controls years ago.

In those cases it were one of the "car 2" temporary memory boards of one
axis or the circular interpolation that had to be changed.
Depending on the architecture of your control there might be some
hardware section
dedicated for the calculation or supervision of circular interpolation.
Take into account that practically all elder controls ought to be fine
tuned
frequently with an oscilloscope for to be able to make proper circular
interpolation. And this has to be done before you tune the back lash.

There are still some of these dummy monsters GE 550 working in this
country.
These things suck more electricity than the main spindle and are
extremely
affected by voltage surges. A very good help on them is to through out
the
old power supply and put in a modern one. Or supply the control separate
over a UPS with battery. By the way the are a perfect training object
for
an electronics in failure searching.

Hope this is of some help.
Sven Peter


"Carey L. Culpepper" wrote:

> Ballendo: The machine still makes the original "angular" rollers perfectly. Actually it will do the roughing passes on the parts
> with arcs until it goes for the finish pass. Then it goes nuts. Everything looks good until it hits the code for an arc. Sometimes
> it just keeps going straight. Other settings did a chamfer instead of an arc.Nothing resembling an arc.
> I did cheat the system by using the CNCPro driver and reconfigured to use x-y axis (easy to do with cncpro-tis in the setup,no
> changing wires) and did use G18. Same bad stuff but I had to try it. Doug emailed me back and recommended trying relative
> coordinates. Then it followed an arc but didn't cut the part the same as the drawing. I found trying to use relative coordinates
> difficult to set up where to set the tool to start to wind up with the correct diameter. I did take some time and made up a
> penholder that is held in a magnetic base to draw the part on paper so I would get a hard copy of where the machine was going. I
> have tried a lot of things -drawing in different quadrants-changing axis direction-cutting direction. I have tried so many things
> that I am probably duplicating attempts. It will probably be a driver setting that is the problem. I sent Don a screen print of the
> driver setup and the roughing finishing setup windows. Waiting to hear back . He had to work till noon today. I am about ready for
> the looney bin at this point. Thanks,Carey
>
> ballendo@... wrote:
>
> > Hi Carey,
> >
> > Don's probably got ya covered, but just in case...
> >
> > First, Can you correctly make the "previous" rollers now!? Using
> > whatever means you used before? If so, then you know there is no
> > change in the system functionality. If NOT, then you know to look at
> > ANY changes made since they last ran correctly. I would keep trying
> > to run them until they are cutting correctly; THEN go to the "new"
> > stuff.
> >
> > Don mentioned G18. You could also use g17 (xy plane for arcs)
> > and "cheat" by changing the cables to the motors.
> >
> > Sorry I can't do more than this. I have mentioned in the past that I
> > have experienced some "strange" output from CncPRO... usually
> > excessive Z motion. Would this correlate to your problem? I.E., the
> > arcs are ellipses or worse, jagged ellipses?
> >
> > Hope this helps.
> >
> > Ballendo
> >
> > --- In CAD_CAM_EDM_DRO@y..., "Carey L. Culpepper" <mr.c@b...> wrote:
> > > I am in need of some help. I am doing lathe work on my cnc converted
> > > Hardinge hlv-h lathe. I am making forming rollers for specialized
> > sheet
> > > metal shapes. The first sets of rollers were strictly angular flats
> > and
> > > angles. The next stages require arcs (fillets). I cannot get my
> > machine
> > > to cut the arcs. It machines all of the flats and angles perfectly
> > but
> > > does weird things when it gets to the arcs. The drawings and gcodes
> > are
> > > Vector 8.2 generated. I even went back and altered a previous BobCad
> > > drawing(which was used to make the previous rollers without problem)
> > > with some fillets. Same type of problem. I have been working on
> > this for
> > > several long frustrating days. I have talked with Fred and tried
> > some
> > > things and emailed Doug and tried doing it with relative coordinates
> > > which did result in some arcs but still not accurate to the
> > drawing. I
> > > am using CNCPro as a control program. I have tried drawing in
> > different
> > > quadrants, all manner of different things- all wrong. This is
> > probably
> > > something really simple as far as setup(to the experienced
> > operator) but
> > > I just haven't found it yet. I made up a pen holder to draw the tool
> > > path on the lathe and have gotten some rather unusual shapes. Fred
> > and
> > > Doug have been very helpful but it is the weekend and I am
> > desperate.
> >
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