Re: How Would You Design question

Hi Tim,

If you had a linear rail system to hold your 37 inch long part, it
would need 37 inches before the blade, 10 inches for the blade and
another 37 inches after the blade to allow a fully supported part to
pass. That is if you chose to go that route. Of course that is a
full lenght hold, you might be able to let then ends cantilever off
the rails, but vibration could effect accuracy and finish.

The clamp could be a vacuumm holder on said table. that would allow
you to cut very close to the end of the stock (side of the stock?)

If you slid the stock(part) in a channel, only the stock would move,
but you need to hold the stock very steady to get the tollerances you
listed.

Very interesting project you posted, seems that if you are using a
material that can take the bend, a meat slicer type saw would all but
eleminate scrap, whereas a standard circular saw blade would chew up
more than half of your parts in dust.

--- In CAD_CAM_EDM_DRO@y..., "dave_ace_me" <davemucha@j...> wrote:
> Hi Tim,
>
> It seems from your post that you want to hold a 37 inch long piece
of
> wood, and have it pass the blade to cut thin slices, 37 inches long.
>
> a moving table holding the wood would need a sturdy clamping system
> and about 7 feet of actual travel.
>
> on the table you would need to advance the part by small ammounts.
>
> this should not be too difficult, as once the first cut is made,
all
> remaining cuts can be referenced from the previous cut.
>
> It seems then that your choices fall to moving the whole 7 ft slide
> assembly forward by 4 inches, or to mount the part advancement on
the
> table and just move the part forward by the 4 inches.
>
> The feed rate is not a critical design problem as you can easily
> accept a large variance from actual. ie: 8 ipm or 8.5 ipm would
not
> be a problem.
>
> the slow and accurate 4 inch feed could easily be a micro
adjustment
> at a maximum of one IPM.
>
> I would look into timing gears, leadscrews and linear rails.
>
> To meet your $$ you will need to get surplus, but I think if you
> doubled your $$ you could buy new.
>
> If on the other hand, you are making 3x4xthin wafers, a chop saw
> design could be done with less.
>
> Dave
>
>
>
>
>
>
> --- In CAD_CAM_EDM_DRO@y..., "Tim Goldstein" <timg@k...> wrote:
> > Been thinking about creating a specific purpose CNC machine and
> thought it
> > would be help to see how some of you would attack the problem.
The
> question
> > revolves complete around the mechanical design of the equipment
and
> does not
> > at all consider the electrical or software from the motors to the
> computer.
> >
> > Here are the design parameters:
> > 1) The machine will be single purpose to cut sheets of wood off
of
> blocks
> > with a maximum dimension of 3" x 4" x 37"
> > 2) The resulting sheets need to be consistent in thickness over
the
> lenght
> > of the sheet + - .0025
> > 3) The thinnest sheets cut will be .050" and the thickest will
> be .200"
> > 4) The cutting motion travel will need to be in the speed range
of
> 20 - 60
> > ipm with a rapid backfeed in the 200+ ipm range.
> > 5) The actual cutting equipment will be a high end table saw with
> very good
> > bearings so that the spindle rigidity, run out, etc do not need
to
> be part
> > of the design discussion
> > 6) The designed mechinism has to fit on and be compatable with a
> high
> > quality table saw
> > 7) The mechanical portion of the design (not including motors,
the
> base saw,
> > electronics, or software) should be able to be constructed for
> about $500
> > 8) Specifying expensive components that are commonly able to be
> found in the
> > surplus market to meet the cost goal of #7 is acceptable.
> >
> > I think that pretty well lays out the general requirements I am
> trying to
> > meet. Look forward to the various ideas that everyone may have on
> how to
> > accomplish this. I have some ideas in mind and it will be
> interesting to see
> > if they are consistent with the group consenses.
> >
> > Tim
> > [Denver, CO]
> > http://www.KTMarketing.com/CNC.html