Introduction to CAD

by leonidsurpin on May 26, 2011

Why did I decide to write this introduction?

CAD stands for Computer Aided Design.  Recently it really became a mainstay of goldsmiths, jewelers, and others involved into Jewellery Industry.  However, growing popularity of CAD have not translated into better understanding of it.  What makes matter worse is that some individuals, who are completely ignorant of the subject, are putting themselves forward as “experts”.  As a rule such “experts” invariably have a cadre of stooges, who under the guise of participants of a debate, simply regurgitate whatever comes out of the mouth of “the expert”.  Such situation makes it impossible to intelligently discuss the subject, and only adds to the confusion.  This write up hopefully will clarify some issues about the CAD.  It should enable someone with limited background to start in this field in the right way.


Shopping for CAD.

So you decided to purchase a CAD package.  How do you know which one is right for you.  There are so many on the market, and every vendor claims that his/her is the best.  You have downloaded some trial versions, but it is of little help.  So what do you do?


To be able to evaluate CAD package one must know what CAD is, so the place to start is the fundamentals of CAD.

CAD package can be simplistically subdivided into CAD engine, CAD interface, and CAD library.  Very often, in advanced packages, there are also DBMS layer ( Data Base Management Software ), but we need not to concern ourselves with it.  Industrial strength CAD packages have many components.  Still, for our purposes, we will think about CAD as comprised of 3 functional units – engine, interface, and library.

Interface is part of CAD responsible for accepting user commands, which can be in form of mouse movements, keyboard shortcuts, and in some cases as text files passed via parameter list.  Upon receiving the commands, the interface converts it to internal format and passes it to the engine for processing.  Both, the engine and the interface, make use of the library.


Most CAD packages employ the same library routines, which were developed many years ago by colleges like MIT and many others.   These routines were numerically optimized, tested over an over again.  There is no need for a user to be concern about library component.


CAD engines are different matter.  How does one test CAD engines?

There are special software packages, some in public domain, which are designed to test CAD package.  You can try to find some of them on the Web.  But even if you can’t, you can easily test it yourself.  Create a shape of high complexity.  Let’s say start with a mesh of 10000 triangles and try to manipulate it, using tools provided by interface.  If everything is fine and software responds smoothly, increase number of triangles to 100000 and see how it goes.  Eventually you will notice that software become non responsive, so you know that you have reached the limit.


Some salesmen would try to deflect it by saying that you need more memory.  Just ignore them.  You are testing different packages with the same hardware configuration.  It is true that any computer will benefit from more memory, but the task is to find out which CAD package works best on your machine.  Even badly written package can run relatively well on computer with huge memory.  We know that, don’t we?


Interface presents the most challenge for the novice.  We really have to get our hands dirty now.


Believe it or not, but CAD is very dumb software.  In it’s core it can only understand mathematically defined point.  Everything else comes from this simple concept.  What is a line ( edge is correct term ), but not 2 points.  A triangle is 3 points connected by 3 edges.  Four triangles can be assembled in pyramid, simply by making sure that  corresponding vertices coincide.  Many pyramids can be assembled into various shapes. And etc…

The same principle can be applied to many geometrical solids, which give almost unlimited possibilities of creation.


I am omitting discussion of Bezier curves, various splines, and etc…  These are mathematical descriptions of collections of points.   At the very heart of it, the point is still the king.  However some background can be helpful.  Spline is a very flexible ruler, which can be made of various materials.  It was employed by architects until the World War II, and after that in some countries.  If architect wanted to know what material can be used for a beam, a splines of different materials were subjected to loads, and their behavior was observed.

The load was provided by weights called ducks.  Getting one’s ducks in a row expression, comes from this practice.  When splines became computerized, ducks become control points.  Different materials were abstracted by different types of splines, and etc…  So do not get taken by fancy terminology.


Once you understood that, the interface can be evaluated.  Suppose you want to create a geometrical solid consisting of 1000 facets.  The question is how easy you can accomplish that.  The best case is one click of the mouse, and the worst case is to specify each and every point of each and every facet, comprising your desired shape.  Depending how well the interface under testing scores, would give you an idea of how good the whole package is.  In another words, do not just try few primitives.  All CAD packages can do it well.  Try to do something crazy and see how well your request is handled.


The very best way to start with CAD is to start with package like PovRay.

It is true that it may take you a year or more, just to get comfortable with it.

But if you master PovRay, any other CAD implementation will be a breathe.

So, in essence, you have two options.  You  can start with PovRay, which is free and only takes time to master it.  Or you can purchase a commercial package, which can run few thousand, and after investing a lot of money, you can start attending courses provided by the CAD vendor, for which you have to pay additionally.  After about a year or more, you will be at the same place, as far as knowledge of CAD, but one way will cost you only time, and another way will be the same amount of time plus a lot of money.

The choice is ultimately yours.  I do not want to create an impression that PovRay can replace industrial strength software.  It cannot.  All I am suggesting is to delay the purchase of CAD package, until you acquire the knowledge necessary to evaluate it.  And short of taking a college course, PovRay is a very good way to do it.

The website is

Manual can be seen at


Leonid  Surpin






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Influence of Poison on Silverware Design

by leonidsurpin on March 6, 2010

Influence of Poisons on Silverware Design.

March 6, 2010


We often use things surrounding us without much thinking of their origin, and why they are this, or that particular way.  I have always been interested in old techniques and very frequently the best way to decipher a manufacturing method is to understand the reasons behind it.  Silverware design in general and shape of drinking vessels in particular, is an area of exploration of this writing.


To understand silverware design, we have to deal with dark pages of Human History.  This is simply unavoidable.  We all like to believe in goodness of our fellow human being, but History lessons cannot be ignored.  We need to understand the role of poisons and their effects on civilization.

Poisons in Ancient World.

Here is a link to article, which is a very good introduction to the subject

Poisons In Ancient Rome

For those who do not have time to read complete text, here is an excerpt from the article.

Poisons and poisoning are frequently mentioned in Roman literature. The question whether the murder-rate and the percentage of suicides were greater than they are today is still debatable and cannot be decided with any degree of accuracy. Scholars cannot even agree on the size of the population of Rome itself at any given period, in spite of much research and many deductions. Much less can the death-rates from unnatural causes be determined. However, the crime of poisoning seems to have been much more frequent in ancient than in modern times. Perhaps this can be attributed to the absence of gunpowder and bullets.

The word venenum is derived, according to Walde,1 from Venus and means a love potion. It has three meanings from actual usage: remedy, 2 poison, 3 and magic drug or abortive. 4 The exact meaning is frequently determined by the qualifying adjective bonum or malum. 5 Veneficium means poisoning6 and practicing sorcery, 7 while veneficus or venefica was applied to a poisoner8 or maker of drugs. 9 However, in this paper we are primarily concerned with poisoning.

The first known instance of the crime of poisoning at Rome was in 331 B.C., when a high mortality, the result, probably, of a pestilence, was attributed to poisoning. Even Livy doubted the validity of the charges, but he10 gives the whole account as found in his sources. After many leading citizens had died from the same disease, a slave-girl gave information to the curule aediles that the reason for this high mortality was the poisons prepared and administered by the Roman matrons.

On investigation they found about twenty matrons, including patrician ladies, in the act of brewing poisons, which they declared were salutary. On being forced to drink their own concoctions to prove the charges false, they perished by their own wickedness. Following this, a hundred and seventy more were found guilty of the same offense. The second case of extensive poisoning is found in 186 B.C. in connection with the licentious worship of Bacchus.  After a careful and extensive investigation of four months, carried on throughout Italy, the praetor Quintus Naevius made a grand exposé resulting in the condemnation of two thousand persons. Poisoning was one of the crimes prominently mentioned with the rest.

I want to bring your attention to the underlined sentence in bold.  Bacchus was a god of Wine and Bacchus worship was basically a drinking orgy, accompanied with, let’s use the proper term, lascivious activities.  This is one of the earliest, if not the first, documented case of mass poisoning with wine.  Since, it is unlikely that many people would be targeted for assassination in this manner, we have a documented case mass poisoning with bad wine.  This is an important point for later discussion.

Poisons in Middle Ages and Onward

Let’s start with link as recommended reading.

brief history of poisoning

This website has tremendous wealth of information on subject of poisons.  Also pay attention to the links.  A very worthwhile reading. Here is an except for time conscious readers:

In the 8th Century AD, poisoning took another step forward when an Arab chemist successfully transformed arsenic into an odourless, tasteless powder that would elude detection for at least ten centuries, thus providing the sinister world of poisoners with the convenient and deadly ‘inheritance powder’.

By the Middle Ages, poisons were common trade in apothecaries, and available to the general public. While knowledge in other fields degenerated in the West as a result of religion, knowledge of poisons continued to bloom. Many academic texts were written on the subject by monks, among them The Book of Venoms (1424) by Magister Santes de Ardoynis, which told of known poisons at the time, how they worked, and how they could be treated.

Though most of these texts were unavailable to the public, the populace had their own (dubious) knowledge of poisons as well as equally (dubious) bizarre methods of dealing with poisoning, which included drinking from vessels with alleged magical properties and using charms and religious talismans to ward off poisoning. Most of these were obtained from the Jews7.

As the Renaissance surged through Europe, so did the popularity of poison as a method of disposing of people who were in the way. You could almost say that poisoning had become fashionable — certainly it was the most convenient way of migrating into the upper circle of society. The most infamous example from this era is that of the Borgia family, who migrated from Spain to Italy around 1455 and whose name became synonymous with dinner-party executions. The most well-known member of this family was the notorious femme fatale Lucrezia Borgia8, who formed a ghastly poisoners’ triumvirate with her father Pope Alexander VI9 and brother Cesare, and whose reputation as a poisoner has achieved a sort of mythic immortality.

The study of poisons during the 14th and 15th Centuries, coupled with the experimentation by Italian alchemists to create more potent poisons from classical bases, spread from Italy to Paris, thanks to the efforts of Queen Catherine De Medici10, and paved the way for a boom in the poisoners’ industry as the poisoning epidemic (and, subsequently, paranoia, especially in the upper class) surged through Europe. By 1572, at least 30,000 self-named poisoner ‘sorcerers’ were running rampant in the streets of Paris. A poisoner-assassins’ guild called the Council of Ten was established in Italy during the 16th Century by a group of alchemists, to provide ‘elimination’ services for a fee. A publication called Neopoliani Magioe Naturalis (1589) by Giovanni Battista Porta served as a textbook for poisoners, especially with regard to lacing wine with a deadly concoction called Veninum Lupinum, composed of aconite, taxus baccata, caustic lime, arsenic, bitter almonds, powdered glass and honey, and shaped into walnut-sized pills. An arsenic-infused solution called Acqua Toffana, invented by a Neapolitan woman by the name of Toffana, was marketed as a ladies’ cosmetic under the guise of a ‘miraculous substance oozing from the tomb of St Nicholas di Bari’, but was famous among widows for more sinister purposes11. By the 17th Century, schools of poisoning had been established in both Venice and Rome, and women who had been elbow-deep in poisoning schemes from the start, now took their murderous crimes to a higher level by forming secret societies in which they received not only instructions on the administration of poison, but the weapons themselves. Poisoning had transcended murder to become art.

I have underlined a portion of the text to point out that wine was a vehicle of choice to expose a target of assassination to poison.  That was done because wine could go bad on it’s own, and it was difficult to prove whether poison got into the wine intentionally, or simply was a by-product of winemaking process.

One of the interesting questions to consider is how much of fear was due to actual attempts on life, and how much was because of improperly prepared food and wine.  After all, a lot of things can go wrong in a kitchen or a wine cellar.

To my utter surprise, I discovered that a mere suggestion that wine can become contaminated as a result of wine making process, are a fighting words in some circles.

I do not want to indict their motives, but resistance to that idea are mostly from individual associated with wine industry.  I suspect that they feel that somehow it could affect their business.  I want to put their minds at rest.  I am not on a crusade to put them out of business by making people unease about drinking wine.

Let’s consider what could had gone wrong with winemaking process, to turn wine into deadly poison.

There are number of fruits and vegetable that contain cyanide compounds which can be converted to deadly form of cyanide upon ingestion.  Here is text, compliments of Canadian Food Inspection Agency

nothing special about this particular text, here is another one

The point been is that a winemaker, facing a bad crop but needed wine to survive, because it was the only thing that he grows, could be motivated to use other fruits for winemaking, and some of these add-ons could had contained cyanogenic compounds.

My friends from wine lobby arguing that grapes do not contain cyanide and/or cyanogenic compounds, which is true, but is that a complete truth?  Let me introduce a new actor, whose name is Snow Mold.  If you are not a gardener, you probably would not know who it is, so here is the explanation

Once you familiarize yourself with our little friend, it is time to read following text

I know it is heavy going, but stiffen your spine and persevere.  Pay special attention to references at the end.  There are appears to be a tons of literature on the subject.  Do you think that professors of viticulture, who are so often quoted, should know about it.  Snow mold is a very common fungus.  Do my wine lobby friends really want to argue that there was no possibility of fermentation vats getting some of it.  Now fermentation is carried out in stainless steel tanks, which are disinfected before every use, but it was not the case 500 years ago.  And where do you think this practice of cleaning fermentation tanks came from?

Evolution of Silverware design to safeguard against poisoning

As a goldsmith, I am interested the most in how all that was influencing design and techniques of silverware and jewellery.  The raisons d’être of goldsmithing is to meet the demand for things, which make everyday life more fun, so it is very illuminating to examine how our brethren rose to the occasion.

Let’s take look at some examples:

The earliest drinking vessels were horns.  It was believed that horn on contact with poison would vibrate and thereby inform of the danger.  Cellar master wore pieces of horns attached to silver chain.  Before tasting wine, the horn was lowered into the liquid and observed for reaction.  Silversmiths capitalized on that belief and produced number of articles for people who could afford them.  The picture above shows an example of such vessels.  It was made by Jacob Mores, who worked in the period from 1579 to 1609.

Rock Crystal was also used as poison indicator.  It was believed that upon contact with poison, the crystal looses it’s transparency.  This is happens to be a very rare piece.  It was made by Albrecht Jamnitzer, who achieved status of the master only 5 years before his death.  Only a few pieces of his work are known.  All are dated to 1550 – 1555.

Another material used for protection, was agate.  Agate was highly prized gemstone in XVI century, mostly due to believe in it’s magical properties.  Agate would not show if poison was present in wine, agate would render poison harmless, as the legends tell us.The cup was made by master Elias Lencker, who worked in 1562 – 1591

Use of the ostrich egg shell is very interesting.  A very wide-spread superstition in Middle Ages was that any egg shell, after egg was eaten, must be broken.  If not, than a witch could make egg shell grow as large as a boat and use it to get around to do evil deeds.  Ginrich Ohmsen, who made this goblet between 1636 and 1640, solved the problem by encasing the egg shell into silver cage.  Now it was impossible for any witch to turn it into a boat, and he would not be responsible for enabling witchcraft.  The egg shell would give the same reaction to poison as mother of pearl.

One would be remiss not mentioning use of Nautilus shells.  Nautilus shell was also known as “Ship of Pearls” due to high quality mother of pearl, lining it’s inside.  One motivation for using this material, could had been to associate with legend of Cleopatra, who was drinking pearls dissolved in wine to enhance her appearance.  If poison was present, mother of pearl would loose it’s sheen and transparency.  Master unknown, dated pre 1644

This is what is known as double goblet.  A smaller goblet is used as cover as well as goblet.  What is interesting about it is that repousse was used not only as decorative technique, but also as structural.  The teardrop volumes stiffened the whole structure, and at the same time showed off superior reflective ability of silver.  It should not be overlooked that on the inside, the edges of these areas would be first to react to presence of poison, so even minute discoloration would be noticeable due to it’s shape.Unknown master, dated pre 1520.

Another interesting type of silverware are salvers.  The name itself is very revealing of the purpose.  Etymology of salver from French salve, from Spanish salva (tasting of food to detect presence of poison), from salva (save), from Latin salvare (to save). Another term for this former practice of sampling food is credence.

Let’s look at some examples

Master Hans Brabant, worked 1535 – 1569.  Mother of pearl medallions function as poison indicators.

Center composition in silver, functions as poison indicator, but it does more than that.  Composition depict the finale of legend “Apollo and Daphne” when Daphne just about to be caught, turns herself into laurel tree.  Since cherry laurel was primary source of cyanide in Middle Ages, it is possible that a warning was intended.  Master Ditrich Moye, worked 1633 – 1653.

Master Hans III Lambrecht, worked 1630 – 1683.  I have included this salver not because of some unusual technique, but because of it’s composition.  Floral elements on gilded background.  The artistic sense of the goldsmith is impeccable.  This salver could have been made yesterday.  There is absolutely nothing to pin it to a particular time period.  A truly timeless masterpiece.


The word poison conjures up images of evil and suffering, but as we know now, it was discovered in pursuit of love.  In search for the antidote, a lot of beautiful things were created and medical knowledge was advanced.  If not for poison, the profession of goldsmith probably would not exist.  Should we be surprised by creative force of poison in general and cyanide in particular ?

As a parting gift, I will present you with this link

Judge for yourself.

Leonid Surpin.





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