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Ancient Machining debate


Date: Tue, 25 Mar 1997 12:51:38 -0600
From: Chris Dunn 
Subject: Re: Advanced Machining in Ancient Egypt
Newsgroups: sci.archaeology
Message-ID: <859296532.26980@dejanews.com>
Organization: Deja News Usenet Posting Service
References: <332CF4CF.6BD6@eoppsun.estec.esa.nl


This is in response to all the activity in this newsgroup regarding my
article "Advanced Machining in Ancient Egypt?"

I am gratified by the debate that has sprung out of my posting of the
article on Laura Lee's web page last year. I was hoping for this kind of
debate in 1984 when I first published the article. The technology at that
time, though, wouldn't support this kind of interactive discussion. At
least not in the world in which I was living.  I wrote the original
article on a Commodore 64 computer. After 17 years, my work is finally
receiving the serious atttention which I had originally hoped to inspire.

I was alerted to this debate by Rodney Small and at first decided not to
participate. In retrospect I realize that I was "burying my head in the
sand." Then curiosity got the better of me and I scanned the posts via
Dejanews in amazement at the interest and discussion Advanced Machining
in Ancient Egypt [AMIAE] had attracted. I was stimulated, challenged and
impressed by the vigorous riposte.

I welcome the arguments that counter this theory. This theory has been in
print for almost 14 years without a serious response by defenders of
orthodoxy. I was somewhat remiss, though, when I revived it in 1995. I
did not include the reader as a part of this quest for truth. If you will
look at the original article, you will see that I offered a challenge for
the reader to think of another way the characteristics of the hole and
cores could be produced. I also included a caveat to the effect that
 .."if there is, the answer that follows could be disproved."

Also, in the last paragraph in my original article I stated: "…….there's
sufficient evidence to justify another look at the Pharaoh's
stonecutters. In considering this interpretation, though, an
unquestioning total acceptance could be as bad as an unquestioning
rejection. It is meant to stimulate thought, discussion and, hopefully, a
sincere objective study of the artifacts in question by anybody with the
resources to do so." Since 1984 I have hoped for an opportunity, such as
this, where there is a tremendous interest in the replication of the core
using conventional methods and the method I hypothesize. Intellectual
resources are the drivers for such an enterprise, and I will address the
more meaningful and knowledgeable comments and technical analyses that I
have read in the posts. This does not mean that other debaters did not
make good points and articulated their views well.

Miguel Maguirre is a champion of orthodox beliefs, and has proved himself
to be in possession of more knowledge of technology than others. It is to
his knowledge, integrity and professional training that the remainder of
this post speaks.

<< Maguirre writes on March 17, 1997:

>First: Dunn article is long and well presented. It is much
>better structured and more logic that almost anything has
>ever been written in the Extraterrestrial in the Antiquity
>type of literature.

CPD--- Where did you find me invoking extraterrestrial help in my article?

>Second. Dunn knows a lot about machining. Indeed he knows
>more about general machining than me. On the other hand I
>know more than him on advanced and high accuracy machining
>and on high accuracy metrology.

CPD--- No comment.

>Third. Dunn is in general honest. I understand what he is
>talking about and he could have exaggerated or lied to make
>his article more interesting. He does not do it. I have to
>retire my statement that he settled on ultrasonic machining
>to add spice to his article.

CPD--- Good.

>His article is very long; so, I will answer only the points
>of substance. I hope that I have not forgot anything
>important. I include now each Dunn¹s statement followed by
>my comments

>1) He has not seen laser machining on old Egyptian work.

>I agree

CPD--- How could you not?

>2) Egyptian used lathes to produce diorite bowls and to
>machine sarcophagus lids.

>Assuming that the description of the things he claims to
>have seen is correct, is reasoning is impeccable and he has
>to be right.

>Nevertheless a lathe is just a variation of the potters
>wheel. Indeed a lathe is just a horizontal potters wheel
>with the cutting tool acting on the place of the hand.

CPD--- You are trivializing the scope of the work. So a potter's wheel is
just a vertical lathe. And the ancient Egyptians had potter's wheels that
held huge pieces of granite for the cutting of radii. (And wheels weren't
even invented then?) I'm sorry, I can't accept this argument. I've worked
on large vertical lathes, (vertical boring mills for you chaps in the UK)
of the kind that are capable of bearing the weight and turning objects of
this size and geometry. We know how pottery wheels are designed and
utilized. We can forget about them. The tool marks on the sarcophagus lid
had, what appeared to me, clear indications of being turned on a lathe.
Before you dispute me, take someone who has had first hand knowledge of
this kind work to the Cairo Museum to support your statement.

>Also lathing is not too appropriate to machine stone. Stone
>is fragile and hard. Lathing needs a sharp tool harder than
>the item you are working with. It is not logic to lathe
>stone. Nobody lathes stone today. They use milling and
>ultrasonic machining.

CPD-- Then either my observations are incorrect, or my impeccable
reasoning for lathing, (turning) is weaker than my claim for ultrasonic
machining and milling?

>So, his claim of lathing is strange.

CPD-- Explain how they created intersecting radii with sharp cusps as
Petrie described them. I knew a chap in Indiana who lathed stone, using
carbide tipped tools. Of course he was working with limestone, not
granite. But your point is a good one. They must have been using a
technique of lathing stone that we are not currently practicing. Or at
least not that I'm aware of.

>My conclusion is that this point cannot be settled without
>detailed study of the items.

CPD-- I don't expect any point to be settled without detailed study.

>3) 0.1 inch is an incredible feed rate for drilling granite.

>I fully agree

>Dunn agrees with me: it is impossible to cut granite with a
>tool at this rate. Indeed it chooses ultrasonic drilling
>because it does not cut in the conventional sense

>That he agrees with me is clear from reading his article. He
>has to invoke a mistake to justify the infamous 1/60
>thread. Now I quote him:

CPD-- I must have missed something. When and what did you say that I
agreed with?

>Dunn++++++++
>The fact that there is a groove may be explained several
>ways. An uneven
>flow of energy may have caused the tool to oscillate more on
>one side than
>the other. The tool may have been improperly mounted. A
>buildup of abrasive
>on one side of the tool may have cut the groove as the tool
>spiraled into
>the granite
 >++++++++++++++

Do you find this kind of speculation unreasonable?  These kind of mental
exercises go on everyday in industry. It is part of the job of being a
manufacturing engineer.

Example: Jack is laser cutting a sheet of 300 SS. The laser turns a
corner and Jack finds that where the laser changes direction there is a
jaggedness to the edge. So we troubleshoot it. Is it a mirror mount that
has come loose and shakes through the forces of momentum and intertia? Is
it the result of a bad thrust bearing on one of the axes' ball screw? Is
it the result of a brinelling of the ways after a CNC program with a bug
caused the machine to crash yesterday?

Example: Jack is cutting holes in Hast-X on a CO2 laser. He finds that
the holes, which are supposed to be round, are elliptical in shape. Is it
the following error on one of the axes? Has the controller lost its axes
compensation table? Or is there a bad mirror in the circular polarizer?

The first question you have to ask is, 'does this deviation from perfect
meet customer specifications and allow the fit, form and function for
which the product was designed?' If not, you have to pick one hypothesis
and work through each until the problem is solved.

>Conclusion: he agrees that a ultrasonic machine working
>properly does not produce threads

CPD--- You have to define what properly means. If the grooves are the
natural result of an economic process and do not detract from the purpose
of the artifact, then threads may not only be acceptable but desirable;
for to work the stone to a finer tolerance and finish would take more
time and hence cost more. A laser working properly does not produce a
jagged edge, but if the product is acceptable, what does making it
perfect buy us?

>So this incredible cutting rate is a red herring.

CPD--- Not if ultrasonic machining working properly or improperly
produces threads.

>My preliminary conclusion is that the thread is a mark of
>the REMOVAL of the tool once the machining is finished. To
>verify this will require a study of the marks by electron
>scanning microscopy.

CPD--- How will a SEM verify the direction a tool was cutting? I can
understand how there would be changes in the structure of the quartz at
the atomic level, but please explain how it would determine the
direction.

>4)
>The machining is deeper in the harder quartz than in the
>weaker feldspar.

>I disagree.

>Petrie -that is the source of Dunn- does not say what Dunn
>claims. Martin Stower quotes Petrie

>Stower-Petrie++++

>The deep cutting grooves are scored out quite as strongly in
>the tapered end as elsewhere; and if the taper was merely
>produced by rubbing of powder, they would have been polished
>away, and certainly could not be equally deep in quartz as
>in feldspar.
>++++++++++++++

CPD---Petrie said "and even rather deeper" in Pyramids and Temples of
Gizeh.

>Again Petrie is wrong in machining. Rubbing of powder cuts
>equally all over. This is the reason it is used for the
>production of flats granite tables for metrology.

CPD--- But it did not cut equally all over on the Valley cores. So are
you saying that there was no powder involved?

>Furthermore¹ ultrasonic machining also cuts all equally.
>This is a false solution to a false problem.

>5)
>The hole could have been done by Ultrasonic machining.

>Yes, I agree it could, but it was not. (Note he will make
>the hole but it would be unable to duplicate the thread)
>A true ultrasonic machine would have advanced straight. It
>will not need tapering. Also the tool could have been
>removed straight and it will not leave any thread mark: nor
>advancing neither removing.

>6)
>The hole could have been done ONLY by Ultrasonic machine.

>I disagree.

>The most likely method will be to use a tapered cylinder of
>copper and abrasive dust. It appears that this method is
>already mentioned as the most probable in the book quoted by
>Stower Ancient Egyptian Materials and his Industries.
>Thinking independently on solutions to the problem I had
>already arrive to the same conclusion before I read the
>reference of Stower

>To understand how the system work it is necessary to recall
>that granite is very hard but very fragile and copper is
>soft but resilient. Soft copper will not be eaten away
>because -like rubber- cannot be broken. Just it will
>incorporate broken grains of abrasive and granite in its
>plastic matrix. This will make the tapered copper cylinder a
>very efficient drill (indeed a true composite). The
>problem is that the method will require the tool to be
>retired from time to time because it will be slightly
>increasing in dimensions. To make the remotion easier a
>screw-like movement could be implemented. THIS IS THE ONLY
>CREDIBLE EXPLANATION OF THE INFAMOUS THREAD MARK.

>Note; this changes in dimension are not a problem. The
>tapering allow to compensate for it. Dunn already realize
>it. It justifies the tapering to allow for tool decreasing
>in size, but the principle work the same for tool increasing
>in size. Indeed I have to thanks Dunn for pointing out that
>the tappering is the key. He helped me to solve the last
>element of the mistery.

>So the convention theory explain properly the tapering of
>the hole and the helical thread mark. Ultrasonic machining
>does not, because being more powerful allows to advance
>straight and to retire the tool straight; so no threads

CPD--- I appreciate these comments, Miguel. I agree that ultrasonic
machining would allow for the tool to advance straight into the workpiece
without turning. When I wrote my article, I could also visualize the tool
turning on a thread to advance it into the workpiece. By your statement,
you encouraged me to go back to my original source. In 1983, Mr. Clyde
Treadwell, president of Sonic Mill 7500 Bluewater Rd., Dept.T,
Albuquerque, NM 87121 critiqued my article before I published it. I was
referred to Clyde by Mr. Jerry Patry of Branson Sonic Power who described
him as "America's foremost expert in impact (ultrasonic) machining." He
found my conclusions, as they relate to technology, logical. I talked to
Clyde on 3/21/97. The questions I asked him were prompted by your own
claims that ultrasonic drills do not rotate and do not leave grooves.

Dunn: "Is it conceivable to you that an ultrasonic machine could employ a
trapanning drill that rotated by a screw method to apply pressure to the
workpiece?"

Treadwell: "We have such a machine."

Dunn: "Is it conceivable to you that such a machine would leave grooves
in the hole?"

Treadwell: "If the drill was overpowered and forced into the ceramic,
this condition would arise."

Dunn: "The cores that were broken out of the holes had a spiral groove
that  indicated a feedrate of .100 inch/rev. In your opinion, is this
reflective of the feedrate that would have been used to drill the hole?"

Treadwell: "These kind of spiral grooves could appear when the drill is
being withdrawn (threaded) out of the hole." (Treadwell confirms your
preliminary conclusion, Miguel.)

Dunn: "But the hole and core are both tapered. The core is smaller at the
top and the hole is larger at the top. Wouldn't the tube drill clear the
surfaces as it was withdrawn?

Treadwell: "The trepanning tool could be a straight tube. Tapering of the
hole and core will happen if the tube is mounted off-center [to the
machine's rotational axes.] As the tube goes deeper into the material the
center point of the tube's diameter at the cutting edge moves closer to
the center point of the machine's rotational axis. When being withdrawn,
it remains in contact with the hole and core [as it regains its
off-centered axis from the machine's axis.]  (Treadwell confirms one of
my speculations that the tool may have been improperly mounted.)

Dunn: Could these spiral grooves be cut with the sonic vibrations turned
off?

Treadwell: Yes.

Dunn: Being analogous to a thread, would the root of the groove cut as
deep through quartz, that is proud of the surface, as it does the
felspar?

(Mr. Treadwell did not have a clear statement of fact on this question. I
got the impression that it hadn't been a issue before.)

Dunn: "Do you sell time on this machine for applications, and how much? "

Treadwell: "Yes for $60.00/hr."

Dunn: "How long would you estimate it would take to trepan a hole 4
inches diameter and 6 inches deep?"

Treadwell: "Including set-up - about 6 hours."

Mr. Treadwell then excused himself. He had 5 minutes to drive across town
for an appointment.

Dunn: "May I have your permission to quote you?"

Treadwell: "Yes."

There were some statements made in my article that may have misled or
have been misunderstood. One tenth of an inch per revolution of the drill
is not an incredible feedrate in a conventional way if it is was used to
advance the drill into the granite and does not function to provide
momentum for cutting or grinding. Knowing now that the groove is more
likely to be cut as the drill is withdrawn, or screwed out of the hole,
and can be done so without oscillations, weakens the ultrasonics argument
to a degree. Nevertheless, knowing that all the characteristics described
by Petrie are reproducible with  ultrasonic drilling is encouraging and
supports the technical aspects of the theory, even if at this juncture
there appears to be minor errors in the theory. Are they reproducible
using conventional diamond drilling practices? Possibly.  Are they
reproducible using orthodox methods ascribed by Egyptologists to the
ancient Egyptians?  It seems to me that the best way to answer these
questions would be to work from both ends of the spectrum, and in
between, and then compare the results.

Perhaps, Miguel, you or another professional engineer with orthodox views
will join me in answering all of these questions. Conventional theorists
respect you, and with your knowledge, you would have the best chance of
succeeding on the low-tech side of the research. Start thinking about how
you would apply what you "know" about ancient Egyptian stone cutting
techniques in the real world. Let's decide this issue once and for all.
Like you, I'm only interested in the truth.

I would suggest a research project, under strict control, that would
follow these steps.

1. A complete and thorough study of the cores in the Petrie museum.
Dimensional checks, SEM, etc.

2. Acquire some Aswan granite and rent time on Sonic Mill's machine and
replicate the core. This may involve several attempts, so I don't have
any idea what his final charges would be. There is the question of the
kind of tools that are available, and it could be that special tools may
have to be made. This is all unknown at the moment.

3. A SEM comparison of my core with Petrie's.

4. You, or some other interested party, create a core using simple
stone-working techniques known to have existed in ancient Egypt.

5. A SEM comparison of this core with Petrie's.

In light of the information received from Sonic Mill, and until these
results are in, I will stand behind and assert my original statement in
Advanced Machining in Ancient Egypt:

"------The theory of ultrasonic machining resolves all the unanswered
questions where other theories have fallen short. Methods may be proposed
that might cover a singular aspect of the machine marks and not progress
to the method described here. It is when we search for a single method
that provides an answer for all the data that we move away from primitive
and even conventional machining and are forced to consider methods that
are somewhat anomalous for that period in history."

I will address all the other points you raised at a later date, Miguel.

Sincerely,
Chris Dunn      3/25/1997

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