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Charles Lewton Brain

Tube setting - An Introduction to Setting

by Charles Lewton-Brain - © Brain Press Publications
Tube setting is a simple method of setting that can take as little as five minutes or less per setting given a specified stone size and a suitable tube to fit the stone. The setting is visually clean, has a professional look to it and can be done with a minimum of tools. Note that setting is usually done on jewellery that is finished. Setting is then the last step in the process of making the piece.

Process and procedural understanding Remember that this short descriptive paper can only be a guide as circumstance and individual taste will vary the requirements of the piece. It is however useful to have a generic starting point for dealing with technique. It is the responsibility of the user to exercise their thinking to use the information for maximum advantage. Ways of learning to think for technical problem solving include always going to the Process in an attempt to understand what is occurring with the metal. The Process is what really happens in a procedure, what the material is experiencing in it's most basic terms, of heat or pressure, or flow. With a tubing setting the process is easily understood. Metal is removed from a tube to allow a facetted stone to enter and be supported by the remaining uncut wall thickness of the tube. The remaining metal of the tube wall that juts above the girdle of the facetted stone as it sits on the ledge cut into the tube is then bent and compressed in such a way as to flatten and flow inwards onto the tapering sides of the stone effectively trapping it in place. Remember the decreased circumference from the original outer diameter of the tube and the smaller circumference of its final set position; the material flows into itself to enable the reduction in circumference to occur. One should then imagine all possible methods of attempting this metal removal and stone entrapment.. It is useful to have someone else handy to bounce ideas off in this type of exercise, though many of us including myself often work on technical solutions in isolation so one has to do it oneself. The methods that are examined should be as wide ranging and even silly as possible as long as they will work. In this case it could be anything from etching or scraping or casting to using burrs. By listing them all even briefly mentally one begins to develop an understanding of Process, of what is occurring in a technical procedure. This in turn leads to faster solutions for the technical problems that one experiences. Contrast and comparison of technical procedures and options leads to a knowledge of the nature of the material used and a freer approach to metal working. Craftsmanship is also enhanced in this approach to working.

Suggested tools (see appendix):

  1. Set of round burrs - Wax cone for moving stones around
  2. Set of setting burrs - Point burnisher in handle
  3. Burnisher - Bezel pusher
  4. Bezel rocker - Stone leveling tool (ie: a blunt toothpick)
  5. Pitch stick or other tool for keeping - Burr lubricant
  6. Setting rigid while setting - Safety goggles (wear at all times)
  7. Flexible shaft with foot control

The setting procedure As it is easiest to use tube settings for round stones a round tube is normally used. One can however use other shapes of tubing if one has the appropriate stones. The recommended sizes of round stones for tube setting have a diameter from 1mm to about 6mm. It should be noted that larger sizes can be set in tubing if necessary. At a certain diameter size (above 8mm or so) engraving tools in a European engraved setting technique are recommended. The suggested wall thicknesses depend to some extent upon the size of the setting. In general for diameters below 5mm a wall thickness of 0.5mm is sufficient. Very solid settings for stones with diameters from 8 mm and over are made using a 1mm wall thickness. With the larger sizes an even greater wall thickness is recommended. Standard seamless tubing in silver and gold as well as brass from the hobby store can be used for sizes under about 6mm diameter. These often have a wall thickness of 0.3mm but seem to work well.

In the setting a seat for the stone is created within the tube by removing metal from the inside of it to create a form fitting ledge for the stone to sit upon. As a result the stone must be smaller in diameter than the outside diameter of the tube but larger than the inside diameter of the tube. As a rule when one places the stone on top of the tube and looks straight down at it one can see one half of the wall thickness; the stone covers the other half.

To cut the seat a choice of tools is available. The process is metal removal from the inside of the tube. The seat opening is cut to the exact same size as the diameter of the stone. One can precut the seat by placing the tube in a chuck such as that of a flexible shaft handpiece and rotating it against a burr or even a graver. For production of tube settings the same thing is done using lathe tools and a lathe. The flex shaft can be set up easily with hose clamps to fix the handpiece in place and allow a burr to be held into the rotating tube to cut seats. A sawblade placed upside down in the sawframe can then be used to slice off the completed setting while it rotates against the sawblade teeth allowing one to make seats and cut off several individual settings before having to reseat the whole tube in the handpiece chuck. it is possible to precut a seat and slice off a tube setting in this way in under 6 seconds per unit. Bezels for calibrated stone sizes are often made this way with the seat being precut before soldering in place on the piece.

A straightforward uncut tube can be soldering to an object to create a tube setting. One can remove the metal for the stone's seat by using various tools. Each cutting tool will however be the same size (diameter) as the stone. Best is to place the stone table down on a flat surface, gently place the opening of one's vernier callipers over it and close them gently on the stone. One then carefully removes the stone and passes cutting tools through the gap in the jaws until the same size is found. Both tool and stone will then have the same diameter. A choice for cutting the seat, albeit a poor one is a drill bit. This is an emergency tool as it has a tendency to bite into the metal and either drill too far into the tube or jam and twist it. Better would be a standard setting burr as is often used in North America. This however has the drawback of damaging the walls of the setting severely if it is held the least bit tilted relative to the tube. This can be difficult for even a practiced goldsmith to do and therefore using setting burs often leads to poor quality tubing settings. Setting burs like this also rapidly fill with metal or even burn if too much metal removal at once is expected of them. Most professional setters if using them will therefore first clear metal out using a ball or a bud burr and follow up with the setting bur so it does not have to remove much material, is not filled with metal and can be more easily controlled as to what it is doing; that is which angle it is held at while cutting. A setting burr should be run a a relatively low speed as high speed can burn them quickly. Burning occurs when the burr discolors from the heat of friction which tempers it so that it's cutting teeth dull quickly. The use of a lubricant such as Burr Life ®, a light oil or a hard silicone cross country ski wax can also increase the life of a burr. A note on setting burrs is that it a the rare stone with the exact pavilion angle of the setting burr and the resulting angle of the cut seat can create undue pressure on part of the stone during setting causing damage to it. My preference for tubing setting is to use a ball burr with a medium cut. The main advantage is that it automatically stays centered in the tube no matter what angle it is held into it. This allows much faster working and quickly cuts the seat albeit with a curved profile.

Image of: Tube with seat cut , Drill bit	,Setting burr and Round burr
Tube with seat cut / Drill bit /Setting burr /Round burr

The preferred steps in preparing the setting would then be:
  1. Choose the tube so that wall thickness and material strength are appropriate for the size of stone used (24k gold or fine silver would be too soft). The suggested wall thickness is from.0.8 mm to 0.4 mm. 0.5 mm is a good thickness for most settings. Place the stone on the tube so that when looking straight down on it it covers one half the wall thickness. Check to see that an suitable amount of wall thickness is visible outside the stone to obtain a seat to support the stone. It is suggested that at least 0.2mm be visible. Too much visible means too much work to clear the seat and is resolved by a correct choice of wall thickness for stone size.



  2. Choose a cutting tool to suit. I recommend a round burr the same size as the stone. If it is smaller than the stone it can be manually held against the wall of the tube and run around to cut the seat. Ideal would be the same size as the stone. Note that you can follow up by using a setting burr in the prepared seat to make things crisp. Be aware of the danger of damaging the wall if you tip the burr. I usually just use the round burr by itself in stone sizes less than 4mm. The setting burr as a follow up may be advised for larger stone sizes.

  3. Cut the seat with the burr and insert the stone to check for fit. This checking is done repeatedly. Goldsmiths and setters check everything all the time and it is a good habit to develop as it improves control and decision making tremendously. The girdle of the stone should be about 0.5 mm below the top of the setting. One can set it a little deeper or a little shallower but as a general guide 0.5 mm is a good starting point. If one cuts the seat too deep it is easily brought to the correct depth with a few gentle strokes of a file. When the correct depth is achieved, stop.

  4. Check that the stone is level by placing it in it's setting so that a light source or white wall reflects from the table of the stone to the eye. The table shows up brightly. Then place one's thumb upside down over the setting so that the setting itself is cast into shadow. The reflecting table facet will show up brightly and can be used to judge for level relative to the setting. In a round burred setting the stone will have a tendency to tip. The stone is leveled either by removing it and replacing it with the wax cone or by pressing on one part of the table with a tool, preferably wood or bone. I use small brass leveling tools for this (see appendix).

  5. At this point the method of pushing the wall over the stone to hold it in place is chosen. This could be a burnisher, stone pusher, the side of the bench pin, a bezel rocker, a setting punch or even a point burnisher. A production setter might use a flex shaft hammer handpiece or a kind of a punch with a hemispherical polished cup at the end which is struck onto the setting to close it over the stone like a bezel rocker. A bezel rocker is an almost identical tool with a polished concave hemispherical cup at it's end which is used to set a round tubing setting by placing it over the setting and rocking it. In all cases there is pressure against the part of the tube wall above the girdle of the stone such that it is tapered inwards with sufficient pressure and speed to close it tightly against the surface of the stone. If the pressure is such that work hardening occurs without the metal moving far enough then it may be very difficult to close the tube tightly upon the stone as it will have a tendency to 'feather' or spring back from it leaving a visible gap between the bezel wall and the stone. If this occurs then one has to use a setting punch or extreme force to push the metal downwards, in a new direction of pressure in order to tighten it against the stone. The metal should be moved as far and as fast as possible to prevent this work hardening occurring.

  6. The stone is set carefully with much checking for level. One begins by applying pressure first on one side of the bezel wall at about a 45o angle to the stone and then on the side opposite until the stone is tight. A stone can be set with only two opposite points bent over it but this is not adequate visually for a standard tubing setting. The stone is set just as one might stretch a canvas, by pressing the tube wall over the stone first north-south, then east-west, then the remaining opposite points. Care is taken that the stone remains level. Sometimes this requires bending part of the bezel wall over without the stone in place, slipping the stone into position and then pushing the side opposite to the initial bend over the stone to set it. Finally it is burnished smoothly and tightly to the stone with a burnisher or point burnisher. One uses the least pressure necessary to do the job to avoid potential damage to the stone. As the metal must be moved as far and fast as possible this is a judgement call on the part of the setter. Experience is obviously an asset here. Most setters begin by practicing with glass stones as if one can learn to set glass then one becomes relatively sensitive to the stone being set. The material of the tube must be taken into account with a 14k gold wall requiring more force to move than a 22k or a sterling wall. The least force is represented by a hand burnisher or a point burnisher. Next would come a hand held pusher or bezel rocker and then after that a punch or the rounded end of the chasing hammer (yes that is one thing they are used for). If one uses the hammer then the thumb is placed over the stone to protect it from any missed blow. Most people prefer the safety of using a punch or a hand held pusher to the hammer procedure.

  7. The material around the stone is then burnished tight with some kind of a burnishing tool. The point burnisher may be used to smooth the inside wall of the setting by holding it vertical to the tube and sliding the rounded point around the inside wall against the stone. Once more, pressure is minimal as one does not want to damage the stone.

  8. Sometimes a setter will clean up the inside edge of a bezel type setting (usually in larger sizes) by using a razor sharp very small flat engraving tool to trim the inside edge of the bezel and round it out. It can happen that if less expensive stones with large crown (top) facets are used that the setting appears angular afterwards as the metal has been squashed down on the plane faces of the stone. This tends to happen if the stone is set a little deep in the tube or if the wall thickness bent over the stone is quite thin. In this case one can use the small flat graver to produce the look of a round setting by adjusting the visual thickness and curve of the bezel when viewed from above. This is an example of something goldsmiths and setters do at times which is to adjust the appearance of something visually to make the viewer think it is round or otherwise more perfect than it is.

  9. The stone is now set and the setting finished. Traditionally one might leave the setting without further polishing with the marks of the setter's burnishing tools in place on the metal. Usually one gives the marked metal a slight finishing with rouge, as tripoli would remove the sharp crisp look left by the setter.

Appendix

Descriptions of suggested tools:

Wax cone for moving stones around:

This tool is made by taking a lump of beeswax about the size of the top joint of your index finger and kneading it between the fingers until it becomes soft and pliable. It is then rolled in powdered charcoal (one can file a charcoal block or drawing stick) and thoroughly kneaded to mix it. One adds charcoal powder and kneads again. Occasionally one tries to pick up a pair of pliers with the wax. When it will pick up the weight of a pair of pliers and hold it for a count of ten then the mixture is about right. The wax mixture is then shaped to a conical form and the pointed end is used to pick up stones and manipulate them in their settings. The wax cone will also remove a stone stuck in it's setting by working it down upon the stone a suddenly jerking upwards with the wax. Even an apparently impossibly stuck stone will come out eventually using this procedure.

Stone leveling tool :

This tool functions to produce a small area of pressure on a stone's facet to level it in it's setting. It therefore must have a small end to produce a restricted pressure point and be soft enough that it will not scratch or damage the stone. Traditional materials for such a leveling tool include wood, ivory, bone , copper and brass. A toothpick will work. My favorite is a traditional tool made of a brass rod tapered on both ends with a lentil-like boss in the middle which one presses against with the fingers when using it. A diagram follows:

Image of Stone leveling tool
Wax cone and Brass Stone Leveling Tool

Burnisher:

There are many shapes and materials for burnishers. The process is that a harder, polished material is rubbed with or without a lubricant (it is better with) against a softer material (the metal) giving it a similar degree of polish to that of the burnisher. The burnisher described here is a standard jeweller's or printmaker's burnisher. Usually one blunts the end somewhat with a grinding wheel, emery papers and polishing buffs to impart an end shaped like a thumb to the tool and to give it the highest possible shine I like a compound called Fabuluster® for this. The burnisher should be made out of hardened steel. Sometimes burnishers made of stones like agate or haematite are used and these if well polished give a good finish to metal. Burnishers are often used to highlight edges in jewellery, to give a piece a 'frame' composed of very thin light streaks off the edge itself. They refine details in stonesetting well such as the outside off a bezel or the details of a prong setting by accentuating the edges of all parts of the setting.

Image of Printmaker's or jewellers burnisher
Printmaker's or jewellers burnisher

 

Point burnisher in handle

This tool is made by taking an old or broken burr and grinding the end of it to a point. Care is taken not to overheat it while grinding and thus cause the loss of the temper, which is ideal for a burnishing tool. It is then rounded slightly.with emery papers and polished. this tool can be mounted into a graver handle or held in a universal collet handle such as is used for beading tools and millgrain wheels. Sometimes special burnishing shapes are made from burrs and held in the handle. Most useful however is a simple point burnisher.

Bezel pusher

Pushers come in various configurations, some for bezels and many for other kinds of settings. There are about 18 different shapes in my box of setting tools. One makes them to suit specific situations. Most useful however is a rectangular cross sectioned rod set into a graver handle. The rectangular end of the tool measures about 1.5 mm by 4 mm. This flat end of the tool is hammered onto emery paper to give it a tooth so that it grips and does not slip when it is in use. The tool should if possible be hardened and tempered to a pale yellow so that it does not wear out quickly. The shaft of the tool has it's edges beveled slightly so it is comfortable in the fingers and the back end is set into a graver handle. Like a graver the handle is tucked under the third finger in the palm of the hand and the other fingers closed over it. The feeling of setting the stone is a kind of squeezing of the graver handle forwards to press the setting into place on the stone. One should lock one's legs around the chair and brace one's shoulder when setting with a pusher. The whole body is used to control the tool. Like a graver the handle is held very hard in the hand in order to gain control of it.

Image of Point Burnisher and Bezel pusher
Point Burnisher and Bezel pusher

Bezel Rocker

This tool was described above and is essentially a rod with a cup-shaped depression in the end into which the setting fits. A variety of sizes are needed as one ideally has a rocker which fits the stone one third of the way into the concave hemispherical cup. The cup is rocked north-south, east-west and rotated to set the stone. The procedure is very fast and is a clean setting method, especially for smaller stones. The tool may be made by drilling into the center of a steel drill rod some 5 mm and then going in with a round burr (which follows the drill shaft) to cut the concave hemisphere. It is then polished using felt end buffs or a piece of soft wood in the flexible shaft with some polishing compound.

Bezel rocker  -  Setting fits one third of the way into cup
Bezel rocker - Setting fits one third of the way into cup

Pitch stick or other tool for keeping setting rigid while setting and placing pressure on the work.

This can be made from a six inch or longer length of broom handle. Pitch or some other easily melted and adhesive substance is placed on the end of it and used to fix a piece of jewellery or a setting in place in order to allow easy setting. The piece may be heated slightly and pressed into a prepared platform of pitch on the end of the pitch stick or the pitch may be warmed slowly and kneaded back and forth on a smooth steel surface to mix it and shape it to receive the object to be held. Never let the pitch get runny! Fingers near pitch can be dipped in water to protect them while shaping the pitch. (This is a hazardous procedure-Think!) The setting or object is supported by the pitch so that one can hammer on it or otherwise apply considerable force to the setting without the fear of bending it out of shape. The purpose of the tool is also to fix the setting in place on an axial handle (which is rotated in the notch in one's bench pin) which allows easy use of gravers or other setting tools. When it is time to remove the object if it is just stuck in the top of the pitch it can be gently heated (remember thermal shock and stones do not mix) and removed. Do not quench the setting. Any pitch residue can be removed by soaking for a time in paint thinner or similar solvent. Do not put porous stones like opals into such solvents. A cleaner method is when the pitch is cracked off by sharp blows to it with a bench hammer. If done correctly this leaves almost no pitch residue to remove.

In North America orange flake shellac is often used by setters but I find it too brittle and hence dangerous to be of any real use. I remember too a biologist shuddering that setters would be breathing heated shellac fumes (pitch fumes too should be vented). Other materials like dopping wax are also too brittle. If one is pressing hard on a setting with an engraving tool and it gives way one can put a graver right through one's hand-fairly unpleasant. I recommend black setter's pitch from Karl Fischer GMBH in Pforzheim for this purpose. It is warmed with heat from a hair dryer, heat gun or the part of the heat from a torch flame where you can still hold your hand-not too hot. If the pitch bubbles and smokes it is far too hot and is being damaged as well as becoming very runny and dangerous. Wear goggles around pitch. Be aware of the burn hazard.

Pitch stick
Pitch stick



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