Re: I'm impressed - and a GCode question.

Alan,

I see the undercut also... At first I thought it was a radius, but
looking at it closer convinced me it was just a "dovetail cutter"
type undercut. It visually "opens up" the cube, IMO.

Ballendo

P.S. Your description of turning a dovetail cutter to a "single"
tooth threadmill is correct. Don't forget to "dubb" off the tip for
the flat at the minor diameter. Many controls allow arc/helical moves
greater than 360 degrees. Haas allows up to +/-8380. On those which
only allow 360 (or 90!), yes, you would program subsequent blocks, OR
use a loop, if the "L" word is allowed. BTW, using a dovetail cutter
is not ideal for the reasons you mention; most threadmills are SMALL
diameter, to keep the cut more constant, AND to minimise "trailing
edge" interference problems resulting from the helical path. Also
allows one threadmill to do larger variety of threads.

--- In CAD_CAM_EDM_DRO@y..., "Graham Hollis" <ghollis@m...> wrote:
> Alan, It sound to me you are seeing things that are not there. All
the
> curves I can see are the result of a intersection of simple bored
holes at
> 90 degrees to each other. Lathe bored or CNC milled, the result
will be the
> same.
>
> Graham
>
> ----- Original Message -----
> From: "Alan Rothenbush" <beer@s...>
> To: <CAD_CAM_EDM_DRO@y...>
> Sent: Sunday, February 03, 2002 9:16 AM
> Subject: [CAD_CAM_EDM_DRO] Re: Re: I'm impressed - and a GCode
question.
>
>
> >
> > A dovetail cutter, yes, certainly with extra relief.
> >
> > A flycutter, yes, again, with appropriate relief.
> >
> > And both under CNC control. Mind you, the GCode to do such a
thing
> > escapes me. A LONG series of appropriate G02 commands with SMALL
Z
> > increments could do it, I suppose. I'd think that there would be
some
> > decided "staircasing", no matter how fine the Z move.
> >
> > This brings up another related GCode question. Say you took
your
> dovetail
> > cutter and ground it like so < instead of the standard /_ ,
with the
> > angle now being 60 degrees.
> >
> > Is it possible to use this cutter in a mill and program the
GCode to
> > cut a thread ( more than just a single rotation ) all in one
go ? I
> only
> > know of G02/G03 commands, and they're limited to 360 degrees,
aren't
> they ?
> >
> > To cut 10 threads, you'd need to tell the G02 command to rotate
3600
> > degrees ...
> >
> > There would also be finish problems as a result of the
discontinuous cut,
> > but continuous motion. Again, I guess with a SLOWWWW feed rate,
this
> could
> > be minimized.
> >
> > Still sounds like a job for the lathe, though.
> >
> > An endmill ( which was the initial "boast" <G> ), is a no.
> >
> > Alan
> >
> > >
> > >Dovetail cutter. Extra relief ground in if needed.
> > >
> > >Hope this helps.
> > >
> > >Ballendo
> > >
> > >--- In CAD_CAM_EDM_DRO@y..., Alan Rothenbush <beer@s...> wrote:
> > >Have a closer look. The insides of the cube are curved. Can't
for
> > >the life of me figure out how to do that with an endmill and a
three
> > >axis machine.
> > >
> > > The cube was almost certainly bored on a CNC lathe, with the
boring
> > tool
> > > taking a curved path as it proceeds through the piece.
> >
> > --
> >
> > Alan Rothenbush | The Spartans do not ask the
number of the
> > Academic Computing Services | enemy, only where they are.
> > Simon Fraser University |
> > Burnaby, B.C., Canada | Agix of
Sparta
> >
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