Re: [CAD_CAM_EDM_DRO] Bridgeport CNC Mill???

Lew ...
we were talking about inverse kinematics.

As far as I know, this is NOT, repeat not, offered on the vast majority
of machine tools today.
Std fanuc controls, mills, lathes etc etc dont have it.

Avg machine tool age in the world is about 15 years, I think.
Given that machine tools are capital goods, and last for 20-80 years
depending on care and the type of tool.

The vast majority of new tools, today, are cnc tools. Purpose of this group.
Of those, maybe 1% have inverse kinematics. At most.

Of the mach3 users, 50.000+ of whom are commercial users, and by
deduction maybe 4x that, 200.000 are hobby users, none have inverse
kinematics.
We are not seeing inverse kinematics as a great need.
I don´t see them as a great need.

The vast majority of lathes in the world, today, maybe 99%, DO NOT have
DROs.
(Probably 10-50% of new lathes might have DROs ... certainly. Turnover
on lathe, worlwide, at maybe 5%/year, at most. Remember that old lathe
are still in use).
Certainly, lathes have produced great work, and continue to do so, without.
Likewise, probably the most accurate common tool today, the surface grinder.
Again, vast majority worldwide without DROs.

Now, just like accurate DROs (NOT the hobby silly chinese scales that
are inaccurate), inverse kinematics, instant e-stops without losing
reference etc etc. are certainly desirable.
But, given that millions of users worldwide user these tools to produce
a huge amount of accurate parts, they are certainly not necessary.
Desirable, yes. Essential, by no means.

And for a (quite) small subset of users they can certainly enhance their
effectiveness a great deal.
No-one has ever disputed the desirability of certain features.
Desirability "is not eq" necessity.

These are kind of the arguments, usually from US guys, that radar is
necessary for pleasure or commercial boating.
This totally ignores the fact that most of europe, and certainly 95% of
asia, india, china, africa, maanges to fish just finy, day in and day
out without radar.

I live in barcelona, and Spain is one of the biggest fishers in europe.
1/10 of commercial boats I see have radar.
1/10 - 1/20 of pleasure yachts have radar.
Ergo radar is not *necessary*, since for a long time, and today, 95% of
all miles navigated for business or pleasure are done without.

Now ..
as regards proper position feedback, if you mean by that that machine
shave dro´s that is one thing, and that new CNC machine use servos which
have a tolerance within which they move, that is certainly correct and
desirable.
Nevertheless this ignores the fact that it was not always so, even for
industrial machines.

Now, from the point of view of a user, for most it is immaterial how
closely they servo tracks, as long as they make parts to tolerance.
For example, for me as a user, I might make a part on a lathe, with a
simple script/program and then mic it to check for fit.
If the part is too large, slightly, say by 0.01 mm, I can then with
total confidence move the tool 0.01 mm, do another pass (or 2), and be
very confident I am much closer than 0.01 mm to the desired size.

Now, for optimising production, the situation is different, and most
lathes even today will not allow you to either specify or know how
closely to an ideal size that part is made.
Some, a very few, do allow that, I know, but this is by no means a std
feature offered by everyone.

This is one of the very, very good features of EMC2, that you can often
analyse this (I have no idea whether this is possible with most advanced
hw, and I believe generally you cannot do this [w. avd hw that is]).
I believe that with most advanced servo cards/hw, you cannot see how
closely the servo tracks during programs execution.
I know it is possible with some hw combos, unfortunately it is again one
of those things that are poorly documented.

I practice, today, it is not doable with mach3, which is a pity.
I for one would like this, but I am one of the very small percentage of
users who would both like it and be willing to build/install/pay for it
(something, not enormous amounts).

> Proper position feedback is one of those things that seems unimportant
> until you actually start using it. The vast majority of commercial CNC
> machines can do this.
>
> Les
>
> On 03/10/2011 17:34, "hanermo" - CNC 6-axis Designs wrote:
> > The need for this is not great, but the desirability is, very much.
> > Of the approx. 50.000+ commercial users of mach3, who have paid for it,
> > there is no great clamour for instant feedhold / referenced e-stop.
> > It would thus appear that less than 1%, or 500, users have a real need
> > for it, as it is not even anywhere on the radar.
>

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