INTRODUCTION
 he employment of the tack welder in the jewelry industry has exploded in the past five to 10 years. Much of the demand for this technology has been driven by the economic necessity of being able to perform the tasks of assembling jewelry components more quickly and efficiently. The tack welder has been one item of technology that has allowed the bench craftsman to increase his speed and proficiency in a fraction of the time it once took a large part of a career to attain. 
TWO OF THE MOST TEDIOUS AND FRUSTRATING ASPECTS OF JEWELRY ASSEMBLY ARE:

  1. Holding components in place for soldering.
  2. The manipulation and placement of solder beads and chips in preparation for torch work. 


THE TACK WELDER USED IN THIS PRESENTATION IS THE ABI TACK II. SOME OF THE REASONS THIS MODEL WAS CHOSEN ARE AS FOLLOWS:

  1. A compact design makes it an easy fit for the jeweler's bench top.
  2. 2.The lead attachment system provides for an infinite number of different tools to be created and employed, accommodating the unique applications of the individual jeweler.
  3. A two capacitor system provides a wide range of current levels needed for repair and fabrication.
  4. Both tack and fusion welding applications can be accomplished with the Tack II.
  5. The voltage meter provides for pinpoint setting of voltage.

 
THE TACK WELDER ENABLES THE USER TO ACCOMPLISH MANY THINGS:

  1. Temporarily fixture jewelry components in place prior to soldering.
  2. Examine from all angles the alignment of a piece prior to committing to a permanent soldering.
  3. Reposition a component by quickly and easily pulling pieces apart and re-tacking until perfect alignment is achieved. This is especially helpful when working with platinum.
  4. Eliminate the need for jigs, soldering investment, and other traditional holding devices typically used in soldering operations. Many traditional methods threaten contamina¬tion to platinum during torch work.
  5. Tack multiple parts in place. This not only makes the placement of solder and components much more efficient, but also decreases the number of times a piece must be subjected to the torch.
  6. Manipulate and tack solder beads and chips in place with the use of the Vac-Tool, a tack welder accessory. With this tool an infinite number of solder pieces can be fixed in prepara¬tion for one torch operation.
  7. Quickly and profitably perform granulation with the use of the Vac-tool. Often jewelers who take up the tack welder after many years at the bench, wonder how they ever made or repaired jewelry without it. As this technology equips the jeweler to improve his work quality, and move through his or her tasks more quick¬ly, his profitability is automatically increased.

Once the basic oper¬ating principles of the tack welder are in hand, the jeweler begins to see the innumerable applications possi¬ble.

WHAT IS A TACK WELD AND WHY IS IT PARTICULARLY USEFUL FOR THE PLATINUMSMITH?

A tack weld is a temporary work¬ing weld of medium to low holding power caused by electrical resistance created at the point of contact between two parts being assembled.

Tack welding is very beneficial in platinum work. The potential for contamination from tweezers or other holding devices is very great due to the high heat used in solder¬ing or welding platinum. Once plat¬inum parts are soldered or welded together, it is often very difficult to separate them without damaging the workpiece. This step allows you to check the alignment of parts from all angles prior to committing to a per¬manent soldering. If parts are mis¬aligned, they can easily be pulled apart and re-tacked until perfection is achieved. 

BASIC OPERATING PRINCIPLE OF TACK WELDING
Tack and fusion welds work on the same principle as a fuse or older model circuit breaker. In the circuit with a fuse, the energy travels through a large channel of conduc¬tive material, then through a smaller channel, and back to a second large channel.

When the amount of current travel¬ing through the circuit is more than the small channel can carry, that channel overheats and melts causing a break in the circuit. The melt always takes place at the point of greatest resistance, typically meaning the smallest diameter chan¬nel the current passes through. In the case of a tack or fusion weld, the pressure we apply between the two pieces we are joining when the melt occurs causes the two molten areas to flow together and solidify instan¬taneously. The amount of resistance can be regulated by energy and voltage set¬tings and the amount of surface con¬tact between the pieces involved. Too much resistance and damage to the piece may occur. Too little resistance and the weld will have insufficient holding power.

WHAT IS A CAPACITOR SYSTEM?
A capacitor is similar to a battery in that it stores energy and holds it until discharge. How does a capaci¬tor system work to create a tack weld? The Tack II machine stores the amount of energy and voltage you direct when you adjust the ener¬gy and voltage settings. A circuit is created by making contact between two components you're holding with the tools attached to the machine, one to the positive, one to the nega¬tive. To discharge power to the cir¬cuit, simply depress the pedal. The tack weld will take place at the point of greater resistance.

The strength of the weld depends on how much melt occurs at the time of discharge.

THE AMOUNT OF MELT CAN BE VARIED BY:

  1. The energy and voltage settings.
  2. The amount of surface contact between two pieces.
  3. The make up of alloys involved.  When a damaging arc occurs, carefully examine your work to see if the arc took place between the two work pieces, or between the work piece and the holding tool. 
     

IF THE PROBLEM IS BETWEEN THE WORK AND THE TOOL:

  1. You may need to adjust the way you are holding the pieces to make sure you have more sur¬face contact between the tool and the pieces than between the two work pieces.


IF THE PROBLEM IS BETWEEN THE TWO WORK PIECES, YOU MAY HAVE:

  1. Voltage and energy levels too high.
  2. Improper surface contact between the two pieces.
     

TESTING PIECES UNFAMILIAR
Before attempting to tack pieces the operator may be unfamiliar with, always test energy and voltage set¬tings on scrap material of like alloy and dimension. When acceptable results are achieved, record the specifics of the application for future use. Notes should include basic dimensions, alloy of metal, amount of surface contact between the two pieces, and voltage and energy settings.

RESISTING TEMPTATION
If you have trouble joining pieces that previously have worked well at a particular setting, resist the temp¬tation to increase current levels. A weld will eventually take place, often causing damage to the work because of excess current levels. Cleaning and lightly filing pieces at the points of contact will usually remove any material that may inhibit a weld of acceptable quality from taking place at a current level known to be appropriate. 

THE WELD WINDOW
Each different application usually has a different voltage and energy setting.

The optimum setting for a piece falls within what we will call a Weld Window. 

TOOL PREPARATION AND USE
Stock tools and attachments for tack welders are created for the ease of holding pieces in place for tack and fusion in the most efficient man¬ner possible. Jewelers are encour¬aged to make modifications which will best accommodate personal applications and styles of operation.

Make sure to hold parts of work¬pieces together firmly before dis¬charging current. Pieces held loosely together are likely to cause damage to the work, much like a loose wire in an electrical outlet can short cir¬cuit.

It is important when contemplat¬ing tool designs or modifications that you want to make sure and have more surface contact between the tool and the work piece than the pieces to be tacked together. This will help insure that the desired results will be achieved. To do other¬wise may cause the work piece to tack to the tool. Despite our best efforts there are times when you will have some sticking between your tool and your work piece, thereby leaving a spot of tool material on your work piece. As we know, this can contaminate plat¬inum pieces. To alleviate this prob¬lem we line our tools for working in platinum with platinum.

EXCESS ENERGY DISCHARGE
Because a tack welder has a capacitor system, it can store an electrical charge for hours even with the machine in the off position. It is essential when you want to go from one voltage and energy level to a lower voltage and energy level, that excess current be discharged from the system to eliminate the chance of damaging your piece due to excessive power levels not indicated by the volt meter.

GRANULATION IN PLATINUM OR PLATINUM AND GOLD
An exciting new technique for performing granulation has been dis¬covered. Beads of platinum to platinum jewelry, platinum to gold and vice versa can be permanently fused into place with a tack welder and a Vac-tool attachment. Granulation beads are held to the tip of the Vac-tool by suction. The bead can easily be manipulated into place on the piece to be granulated. Holding the bead to the work piece with moderately firm pressure, press the pedal with a setting of 40 to 50 volts on high ener¬gy depress the pedal.

To pave a piece with granulation the above process need only be repeated as quickly as accuracy allows. The key is to adjust the voltage level to the proper level for a permanent bond. Too low a voltage level and the bond will not be permanent. Too high a voltage level and damage to the work piece may occur. 

SOLDER PLACEMENT
The ability to tack solder in place during platinum work is especially helpful due to the blowing force of a typical platinum soldering flame. The process of tacking solder is much the same as granulation, but with much lower voltage and energy settings. Beads or chips of solder can be placed.

Bead solder being the easier of the two to manipulate. Carefully observing how solder is making contact before discharge is very important. 25 to 30 volts on low energy is the maxi¬mum for tacking solder. 

CONCLUSION
The tack welder is a tool of necessi¬ty for today's bench jeweler to remain competitive. Speed and quality are greatly enhanced with the aid of the tack welder. Once the general princi¬ples of tack welding are in hand, it is likely that the jeweler will be unwilling to work without it. 

 

V10N4

 

Principles of Tack Welding
and the New Granulation Method in Platinum
Steece Hermanson, JA Certified Master Bench Jeweler
 GALLOWAY AND MOSELEY JEWELERS INTRODUCTION

This is an abbreviated version of the original work. For full technical details, please consult the original paper.