Re: X-Y Table, Rotary Table for CNC INFO

[I think the original idea of a CNC X-Y table that fits on a manual mill is
better than trying to add a Z-axis to the thing and turning it into a much
more complicated machine. Most CNC work is still 2-axis, and even 2.5 axis
work could be done on this by stepping the quill down (or the knee up)
incrementally and locking it in position for each pass at a known position.
This would be preferable to a wobbly scissor-lift mechanism that would
greatly complicate the mechanics of this, raise its expense considerably,
and degrade its accuracy. Many machinists would be overjoyed if they could
spend a thousand dollars or two and add the ability to cut a smooth curve
accurately in steel. Most have no interest in 3d surfacing, and if they did,
I doubt this solution would satisfy them for long. Make this beefy enough to
hold a Kurt vise, provide good ballscrews and slides for it so it's tight
and accurate, and I think you've got a potential winner. If the demand to
add a Z-axis is there, you can always add that feature in a later version
and charge more for it. In the meantime, supply it with a quill DRO to
calibrate the Z-axis and I predict the majority of users will be happy as
the proverbial clams.]

Just my .01886 euros...

Andrew Werby
www.computersculpture.com

"ballendo <ballendo@...>" <ballendo@...> wrote:
Subject: Re: X-Y Table, Rotary Table for CNC INFO

Les,

We agree on several points. Should not be too heavy. Mechanically
simple. Low profile (scissor lift Z axis fits this well!) Marketing
will be "key" to success.

All we're really talking about here is a cnc router, without the
spindle, mounted on a platform to achieve the z axis motion. Any one
of several currently existing machines could be "platformed" and "re-
marketed" into this arena... But I don't think the REAL equation will
work out the way the thought experiemnt does.

I can see that there might be some demand, but it seems that you're
not getting much bang for your buck?

But I could easily be wrong about this! Maybe a 2kilobuck
CNC "engraving and cutting option" with 10x10 travels for a BP, or
M/D would work in the market. I guess I just don't see how this
price, at the necessary performance, could be met. After all, we are
seeing retrofit prices in excess of this, which include nearly all
the same components...

The differences:
In the retrofit- the motion components are longer/larger. Assembly is
necessary. Structure is not necessary, as the machine being retro'd
provides this. Z axis no problem.(bit of a joke here; as the Z axis
is the most difficult on every machine I've ever designed,
retrofitted or worked on!)

With the small table CNC option- shorter/possibly smaller motion
components(but not if you're thinking 1k lbs forces, IMO). No
CUSTOMER assembly. Any cost savings due to smaller motion components
will be exchanged for the cost of the machines structural parts, and
assembly during mfg. Saved by using the existing machine z axis?
Either you need to retrofit IT (which crosses over into 1/3 of the
retrofit above), OR you have to implement it another way; again
expending time and money...

If you're going to sell to the BP crowd, you will need to have
accuracy at a level equivalent to what they're "used to".

I just don't see how all this adds up positive. The only benefits I
can see is that the tooling and spindle already exists. And the "Gee,
Ya mean I can set that on my BP and cut usin' the "puter"?!? (Which
may indeed be enough, IF the price/value can be met.)

Ultimately, it becomes a "compared to what" issue...

And that would be answered by: Taig, Sherline, MaxNC, etc. If the
price ends up where I think it will; you can iunclude CncJr, servo
products, and many older "used cnc's" now on the market; new enough
to be usable without retrofit, old enough to be in the price range.

The idea has merit. But I think a very REAL cost analysis and
customers needs evaluation may show that the cost to provide will be
far more than the coupla thou bucks so far expressed. (commercially;
a "garage" hobbyist can work for free! And just "think" he's makin
any money)

There's a reason that the commercially offered CNC machines cost what
they do! (I'm including the hobbyist models and m/d retrofits here.)

Hope this helps,

Ballendo