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Waterjet stone carving and degrees of freedom


#1

Does anyone on Orchid have experience with FREE-HAND water-jet
carving in stone?

wiki/Water_jet_cutter tells us the accuracy is down to.005 inches
(.13 mm). That is around the limit of human perception (mine anyway).

The 5 axis waterjet stone cutter is now ubiquitous, wiki correctly
tells us. Any Google search will confirm that. That is high school
geometry X, Y,Z plus A and C axes which as I understand it takes us
into the concept of degrees of freedom (dof) in robotics. Correct,
Mr. Livick? BTW how many dof are there in gymnastic arts?

The human dof of a stone carver far surpass those of any robotic
carver (again subject to correction by experts) but the limitation is
set by the power and accuracy of the carving/grinding “end effector”.

As I Googled on suppliers of waterjet equipment I came across a
picture/video of naval workers fully garbed from head to toe while
they scaled down a ship with waterjet equipment. Coincidentally I was
also studying some cave woman stone carvings at the same time in
those big library tomes with titles like “Art Atlas”. Alas, cave
woman did not have waterjet, nor did the Mount Rushmore carvers so I
wonder - would waterjet as the state of the art stands right now have
done the job better?

The pressure of course is enormous and in the 40-100 PSI range. But
a free hand cave woman, safely suited with a pressure washer on
steroids could do ________ what with a 10 ton block of granite?


#2
Does anyone on Orchid have experience with FREE-HAND water-jet
carving in stone?

Experience?

not in the personal sense, but indirectly, yes, My laser profiler a
couple of weeks ago, took me on a conducted tour of the new water
borne aluminium oxide abrasive 2 axis 8ft by 4ft piece of kit he has
just installed.

Water doesnt do the cutting, is only the transport medium for the
grinding powder that actually does the cutting.

this is on average 80 grit in size.

The water and grit discharge head is only an1/8in above the material
being cut.

His setup will cut up to 6in thick, tho ive yet to see the results.
The whole purpose of going down this “cold” cutting route is to
avoid distortion and slag and back spatter that the “hot” as in
melting the metal and blowing it away with high pressure gases in
laser profiling. Oxygen for ferrous and nitrogen for everything
else.

As for doing it freehand on stone for carving, you would need to see
someone doing it before trying it for yourself.

The water below the cut material is some 3ft deep to adsorb the
energy from the water jet.

With stone carving you would get as much water and grit coming back
at you as well as the lack of control.

See videos of fire fighters holding a high pressure fire hose!! I
think you would get better results with a 3d axis either via a 1 to 1
pantograph or a computer controlled diamond water cooled cutting
head engraving machine.

Think cnc metal milling.

also the pressure on the aerage system isnt low like you mentioned,
its 30,000 psi!!.


#3
With stone carving you would get as much water and grit coming
back at you as well as the lack of control (Ted Frater) 

Yes, I immediately foresaw (as you do) two big problematic issues re
free-hand waterjet carving. First, there is the safety issue and
secondly visibility/control.

But the precision and power of this technology astonished me and its
potential may be far greater than present realizations. Machines to
date have limited degrees of freedom. The artist then must work
within these dof. There is no point in carving a model in clay or
wood or wax and then finding out that most of those little nooks and
crannies which make the difference between artistic success and
failure are beyond the 5 axes of the machine.

SAFETY

I have in front of me a piece of driftwood, palm-sized with hundreds
of grooves and pockets. Nature is a great artist. No 3D scanner can
scan it all and no 5 axis machine can replicate it. But what if the
artist could use a waterjet “wand” inside a safety cabinet with
protected arms that reach inside as you see in labs for biologically
and chemically hazardous material? You point out that the unit you
saw took 3 ft of water to absorb the shock if the blast misses the
target. Does anyone know if airplane windows can take this kind of
shock? As for arm protection, would those hardshell suits of deepsea
divers do the job? Or what about having the artist tele-robotically
control a robotic arm inside the work chamber? That would be safe. It
would be free hand and free arm using an artificial, robotic hand and
arm as is done with the Canada Arm at the International Space
Station. And isn’t that what robotic surgery does now?

VISIBILITY

Next, visibility/control. I don’t know if any technology could
"image" the stone being carved through the water jet and its backlash
as the process proceeds, second by second. Does anyone else have any
insights?

Kevin Warwick presents an interesting and mostly sound principle of
machine development in his 1997 book “March of the Machines”. He says
that for any task which a human does, if you make it specific enough,
chances are a machine can be developed to do it better. The human
artistry we discuss on Orchid is at a higher level than any modern
machine. Some roboticists are trying to reach "human equivalency"
there too but they have a long way to go. However, many specific
problems along the way to a finished work of art can be done by
machine.

It is at least clear that the benefits of solving these two problems
for stone carving artistry are enormous.


#4
As I Googled on suppliers of waterjet equipment I came across a
picture/video of naval workers fully garbed from head to toe while
they scaled down a ship with waterjet equipment. 

My brother was an engineer with Flow International, a leading
waterjet corporation. While we were both on business trips to
Jacksonville, FL, he told me about his then-current project - a
computerized system to clean the hulls of the naval ships using
water jets. His description included a small box and joy stick not
unlike those used for remote controlled vehicles, which would
certainly be a far improvement over the workers described above.
Sometime around this same period, he sent me a steel horse plate he
had cut using one of the water jets at the plant in Seattle. The
most amazing part (to my mind) was that this same system could be
used to cut steel or to wash tomatoes gently enough so as not to
bruise them.

Linda in central FL