Re: Auto tool changers

Ray,

Both Fred and Brian have given excellent responses already. Actually,
a lot of programming books and cnc gurus/teachers recommend calling
the next tool early. The WAY to do it may change(as Brian wrote), but
the habit OF doing it is a good one, regardless of control used.

Compare what you mentioned:

I don't believe that I've ever seen a program where the M6 Txx
command was given before it was needed.

With what I wrote (emphasis added with caps):

Most good programmers will list the "T" word at least A FEW BLOCKS
AHEAD OF THE M06, so the toolchange turret can "get ready"(rotate;
talking 'bout mills here) so as to have the next tool in position for
a quicker tool change WHEN THE M06 ACTUALLY INITIATES THE PHYSICAL
CHANGE to the new tool.

Clearly they are both correct statements. But NOT the same.

Lookahead exists to allow cutter radius comp, and to prevent crashes
and gouging from accel/decel issues. PLC's exist as a semi-
intelligent "servant" OF the control, which distributes the "brain"
power needed to run the machine. But I've not seen them work together
to "predict/discern" the next tool and get it ready, tho' they
could...

Hope this helps,

Ballendo

--- In CAD_CAM_EDM_DRO@y..., rehenry <rehenry@u...> wrote:
>
> >    From: "ballendo" <ballendo@y...>
>
> > Alan,
> >
> > Sounds like you're most of the way already...
> >
> > Yes, M06 and Txx. Most good programmers will list the "T" word at
> > least a few blocks ahead of the M06, so the toolchange turret
> > can "get ready"(rotate; talking 'bout mills here) so as to have
the
> > next tool in position for a quicker tool change when the M06
actually
> > initiates the physical change to the new tool.
> >
> > But you have to be careful. Some controls will switch the offsets
> > used WHEN the "T" word is read. Bad, very bad. Same old, same old;
> > know your control! (Offsets "should" switch with the "D" and "H"
> > words. (Some older controls use different letter addresses for
> > diameter and height offset values)  
>
> Ballendo
>
> Now you've got me really confused with this program it before you
use it
> stuff. It has been my impression over the years that the
combination of
> look ahead and programmable logic handled these kinds of tool
changer
> specific problems in most commercial CNC/PLC's. I don't believe
that
> I've ever seen a program where the M6 Txx command was given before
it was
> needed. Could you list a sample of controls where this kind of
> programming is commonly used?
>
> You are right that as hobby users we need to clarify how a specific
> CNC/PLC "reads" the M6, Txx, Dxx, and Hxx commands before we rush
into
> fitting or retrofitting.
>
> RayH -- U.P. Michigan