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

Marcus,

The "bearings rolling uphill" is exactly what I was thinking of. Many
machines use this! It is stiff in z, low profile, and doesn't put
upsetting moments on the vertical ways. Those ways could be
reduced to just a couple posts since their only purpose is to
constrain in x and y.

I know one can ask "why not just make the whole machine if you
are going to go that far?"

Well that's what kind of intrigued me about the idea when I saw it.
I see it as kind of a marketing thing.

I believe if there was a small clamp-on unit with an xy travel of
ten inches or so and a z of a couple inches it would be a very
attractive way to get cnc capability for manual vertical mill
owners. We are not talking Sherline class here... but something
for hobbyists and small shops that own a Bridgeport or similar.

I know back when I had only manual milling I would have wanted
one had it existed.

One could also make it a stand alone machine with a simple
fixed spindle kit that bolts on.

So I think Larry has a great idea!!

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@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Thursday, January 16, 2003 11:36 PM
Subject: Re: [CAD_CAM_EDM_DRO] Re: X-Y Table, Rotary Table for CNC INFO


> Hi Les:
> Sounds a bit like a screw that has been unrolled from around its
> shaft!!! : )
> Best way for this approach might be a pair of wedges mounted on linear
ways
> tipped up at an angle.
> Kind of like a ballscrew unrolled from around its shaft.
> Do you think four linear ways and one ballscrew would be cheaper than 4
> ballscrews, nuts pulleys and timing belt?
> What about rolling it uphill on wheels (bearings)?
> This thought experiment is starting to show some promise!!
> Cheers
>
> Marcus
>
> ----- Original Message -----
> From: "Les Watts" <leswatts@...>
> To: <CAD_CAM_EDM_DRO@yahoogroups.com>
> Sent: Thursday, January 16, 2003 2:11 PM
> Subject: 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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OT
> subjects, that are not allowed on the CCED list.
> >
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> OFF Topic POSTS: General Machining
> If you wish to post on unlimited OT subjects goto:
aol://5863:126/rec.crafts.metalworking or go thru Google.com to reach it if
you have trouble.
> http://www.metalworking.com/news_servers.html
>
> http://groups.yahoo.com/group/jobshophomeshop I consider this to be a
sister site to the CCED group, as many of the same members are there, for OT
subjects, that are not allowed on the CCED list.
>
> NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY POSTING THEM.
DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO EXCEPTIONS........
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