Re: How Would You Design question

Tim,

Yes, as my earlier post mentioned (and one other I've read since),
move the fence. And use pneumatic pressure against it to ensure
consistent thickness. This would be very easy to attach to the
sliding table, and would provide the needed pressure adjustment
and "spring".

FWIW, The whole rest of the world uses rip fences which are relieved
after the point of actual cutting; but for some reason here in the
USA, we mostly don't (at the home shop level).

Anyway, relieve the fence slightly, and use my reduced pressure idea
to "hold" the sheets away from the blade after they are cut. A long
splitter will keep them on their own side of the off-feed table. They
will be pushed off the low pressure area by the next pass of the
flitch. A system of deflectors could work in tandem with a scissors
type off feed table to "stack" the output.

Buy a stock delta or powermatic sliding table attachment. (It would
help to know what table saw you are using, or plan to use.)Tune it
up; but remember the precision is coming from the blade/fence
geometry and/or relationship. Drive the sliding table movement with a
cable or belt, and you DON'T need this part to be CNC.

CNC the fence adjustment if you like, and use a switch to input the
strokes of the sliding table to your control so you don't cut into
your flitch holding dogs.
You could even feed these ticks into a counter/adder (read PIC) which
would then send a signal to your control s/w when a "full" flitch had
been cut. All your cuts would be m codes to move the sliding table,
with g0's for the fence setting. Even this does not REALLY NEED cnc,
just a DRO.

BTW, I'd use superglue to fasten the flitches to re-usable wood or
plastic flitch holders. These would then be planed or sanded between
uses. That way you use all your balsa, at the eventual expense of
some new flitch holders.

These flitch holders could have a magnet in their underside which
activates a hall switch to stop the cutting passes independently of
the cut thickness.

Hope this helps,

Ballendo

--- In CAD_CAM_EDM_DRO@y..., "Tim Goldstein" <timg@k...> wrote:
> Lots of considerations in this besides the ease of cutting. A knife
edge
> band saw will cause crushing of the wood towards the surface and
drive
> up the density while reducing the stiffness. There is also the
problem
> that a band saw blade wanders and would make the thickness
inconsistent.
> Reducing the waste is not a concern. Turning 50% of the raw stock to
> dust is OK if the resulting product is very smooth and consistent,
not
> sawn, and has the absolute minimum fiber damage on the surface.
From all
> the ways of cutting I have tried using a circular saw blade
produces the
> proper product. You have to take off your engineering hats on this
part
> and accept that marketing says it has to be cut that way. Not put
the
> engineer hat back on to work on the design for this.
>
> I am leaning to using a timing belt to drive the feed for the
cutting
> and a lead screw on the advance feed. I am thinking that the best
way to
> avoid lash on the advance feed it to spring load it to apply
pressure
> against the screw. This avoids the need to use zero backlash type
> systems and should work fine as there is no load or pulling in this
> direction. The part I am still hung up on is how to arrange the
length
> feed so that the + - .0025" thickness requirement can be met without
> building a monstrosity. Something like the 80/20 stock is
appealing, but
> I doubt that it can be consistent down the length. I like the idea
that
> someone threw out to have a stop that controls the cut thickness as
the
> precision part than just becomes the slide against that.
>
> Tim
> [Denver, CO]
>
>
> > -----Original Message-----
> >
> >
> > Hi Tim,
> >
> > not to belabor the point, but can you slice soft wood with a
knife
> > edge band saw blade ?
> >
> > I do understand that a toothed blade would tear while
> > cutting. seems like the best of both worlds.
> >
> > Also, I recently went through a similar plight. I need to cut
lots
> > of aluminum parts with some curves and stuff. Laser and Water
cut
> > cleanly, Plasma is rougher and has a poorer finish, but costs way
> > less. All of those are more expensive than the amount of
material I
> > will use in the next year, so a greater loss of material and
using a
> > router will be the most cost effective method for me, at this
time.
> >
> > I plan on increaseing my total units so will move up to a high
end
> > plasma before too long.
> >
> > If your waste is greather in cost than a planer, you may find a
poor
> > surface and a planer may be more economical in the long run.
> > Of course the second operation adds time and money so may not be
as
> > viable in your situation.
> >
> > Dave
> >
> >
> >
> >
> > --- In CAD_CAM_EDM_DRO@y..., "Tim Goldstein" <timg@k...> wrote:
> > > Causes too much crush and tear damage to the wood structure on
the
> > > surface. More of a concern with thinner sheets than is intended
for
> > this
> > > contraption but it would be one of the unique things about this
> > specific
> > > wood. So the answer is for marketing purposes it has to be sawn
> > with not
> > > additional finish steps.
> > >
> > > Tim
> > > [Denver, CO]
> > >
> > >
> > > > -----Original Message-----
> > > > Tim:
> > > >
> > > > What about sanding?
> > > >
> > > > -- Jerry
> >
> >
> > Addresses:
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> > FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/
> >
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> > to reach it if you have trouble.
> > http://www.metalworking.com/news_servers.html
> >
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