Re: Machining on Opposite Sides

Hi Eric,

How about documenting your efforts with a digital camera? It will be
very educational for those of us who don't have much machinning
experience.

Peter

--- In CAD_CAM_EDM_DRO@y..., "exeric1" <exeric1@y...> wrote:
> Thanks for all the thoughtful suggestions. I've given the problem a
> lot of time thinking about it and decided there are tradeoffs in
time
> in any situation. The part, about 3" by 3" and 1.5" thick will be
cut
> out of a piece of aluminum 48"L by 3"W by 1.5"T and can have about
> 80% of its machining done on one side. I decided the easiest way of
> going about it is to do all the inside pocketing along with
drilling
> first, doing about 6 parts at a time in one row. Then bolt all the
> pieces through a center hole in each directly to the T slots. Then
do
> the perimeter machining and parting off leaving an edge to do a
full
> length finish cut. Then finally do the perimeter finish cut.
>
> Since most of the metal removal is already accomplished on 6 parts
at
> a time I can afford to make a jig for the other side of the part
and
> do them one at a time. With the jig, using the advice of using
a 'L'
> support on the 2 flat side, it will be easy to fix the Part Zero at
> the corner of the 'L'. Not quite as elegant a solution as some of
the
> suggestions but I think equally fast or more so. Thanks for the
help.
>
> Eric
>
>
> --- In CAD_CAM_EDM_DRO@y..., Jon Elson <elson@p...> wrote:
> > exeric1 wrote:
> >
> > > I'm confronted with the problem of machining two sides of the
same
> > > material. The piece is irregular on its perimeter dimension,
that
> is
> > > not square or rectangular or round. I'd like to reference the
part
> > > zero on side 1 on side 2 and perhaps just mirror some of the
> > > commands. I'm trying to avoid having to use edge finders and
such
> on
> > > the opposite side to find the same part zero on the other side.
> The
> > > part has 2 flat sides on its perimeter that meet at 90 degrees
> with a
> > > large fillet between them. I'm using the imaginary point where
the
> > > two lines would meet without the fillet as my part zero on side
1.
> > >
> > > I'm using locating pins along the two flat sides to locate the
> part
> > > and fix the part zero. Any easy way to go about this? I'm going
> to be
> > > making many of these parts and I don't want to have to fuss
over
> it
> > > every time I turn the part over.
> >
> > Sure. Make what I call a 'sacrificial' and our shop calls
a 'scab
> plate'.
> > You take a piece of scrap and drill holes for dowel pins and or
> clamping
> > bolts. You mount the part for the first side, machine, then flip
it
> > over. You might use different holes for the dowels or clamp
bolts.
> >
> > One other possibility is to make a fixture with a part-shaped
> > hole in it, and some fingers that bolt onto the fixture that
holds
> the
> > part from one side. Then, you have more fingers on the other side
> > that grip the part when you tighten thumbscrews. You machine
> > one side, and then flip the entire fixture over for the other
> side. This
> > leaves both entire faces clear except where the fingers are.
> >
> > Jon