Re: [CAD_CAM_EDM_DRO] Re: X-Y Table, Rotary Table for CNC INFO

Dave,

You're right about stubby ballscrews being very expensive.

Most of the real cost the nut, end machining, and end bearings.

So a 5" ballscrew might cost almost as much as a 5 foot one!

You mentioned punch dies.

What if you used 3 or 4 sliding bearing columns like many
die sets but performed z axis with 3 or 4 corresponding
sliding wedges (actually linear cams)? The wedges would
translate a single horizontal motion into an accurate
"parallelogram" type vertical motion. Perhaps using cam
follower bearings with strong spring preload. I have seen
some machines made this way.

Just trying to think of how to get the cost out of something
that you could just bolt on and go... or optionally bolt
on a simple fixed spindle structure later.

Les

Leslie Watts
L M Watts Furniture
Tiger, Georgia USA
http://www.alltel.net/~leswatts/wattsfurniturewp.html
engineering page:
http://www.alltel.net/~leswatts/shop.html
Surplus cnc for sale:
http://www.alltel.net/~leswatts/forsale.html

----- Original Message -----
From: <david_mucha@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Thursday, January 16, 2003 8:36 AM
Subject: [CAD_CAM_EDM_DRO] Re: X-Y Table, Rotary Table for CNC INFO


> Hi Les,
>
> I think a simple adapter on the fine feed of most mills would be very
> easy. just mating gears with a slip connector, like a reverse ring
> gear. I think there are similar units for shaft alignment.
>
> remove for easy manual. all it would need is one mount for torque
> and then just software home setting.
>
> Seems much easier than a rising table.
>
> My punch dies with ball screws are EXPENSIVE in short strokes. I
> think the ridigity would make a power Z better tan a power table.
>
> imho.
>
> Dave
>
>
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "Les Watts" <leswatts@a...>
> wrote:
> > Hi Marcus
> > Hmmm I guess 4 short ballscrews with timing belt or something.
> > Kind of like my wood planer.
> >
> > It would have to be rigid, but it might be so small that it would
> not
> > be too heavy.
> >
> > Just daydreaming really... people often ask if I can design a
> > small cnc with good accuracy for an arbitrarily low price...
> > but the price usually turns out high. Manufacturing even small
> > machine tools in the US is a pretty rough proposition.... consider
> > Bridgeport, South Bend, et al. But one can do it for a hobby
> > with no problems! As a business I only build machine tools
> > for internal use and that has worked out ok. Of course I do
> > design some production machine tool components, but
> > the development cost is pretty high for my customers.
> >
> > Les
> >
> > Leslie Watts
> > L M Watts Furniture
> > Tiger, Georgia USA
> > http://www.alltel.net/~leswatts/wattsfurniturewp.html
> > engineering page:
> > http://www.alltel.net/~leswatts/shop.html
> > Surplus cnc for sale:
> > http://www.alltel.net/~leswatts/forsale.html
> > ----- Original Message -----
> > From: "Marcus & Eva" <implmex@a...>
> > To: <CAD_CAM_EDM_DRO@yahoogroups.com>
> > Sent: Wednesday, January 15, 2003 11:10 PM
> > Subject: Re: [CAD_CAM_EDM_DRO] X-Y Table, Rotary Table for CNC INFO
> >
> >
> > > Hi Les:
> > > Were you thinking of a four poster bed type of setup with a
> central
> > > screw?
> > > Or maybe four timed screws with encoders or steppers slaved
> together?
> > > I suppose you could chain drive them or belt drive them from one
> stepper
> > > too.
> > > That could work pretty well I think, if you used good hunky
> frictionless
> > die
> > > bushings and pins.
> > > I'm thinking of the kind that have sleeves with balls in them;
> the ones
> > > that are used for big punch dies.
> > > You could make the base wide enough that the pins hang over the
> edges of
> > the
> > > mill table as they come through the base plate.
> > > That way you wouldn't lose too much height under the spindle nose.
> > > Gonna be a pretty heavy accessory unless you make the base out of
> > aluminum.
> > > Cheers
> > >
> > > Marcus
> > >
>
>
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