Mounting the Peg Style Head

Mounting the peg style head is not more difficult than, let’s say, fitting a square peg into a round hole. Actually it is not quite that difficult, but there are some considerations that need to be addressed.

First is the square peg. Many jewelers will measure the thickness of the peg and drill the hole to match the size. Then it is a matter of forcing the peg into the hole. The emphasis is on “forcing.” This excessive use of force often results in a distorted or damaged head, and is not necessary.

Another technique is to measure the peg diagonally corner to corner, drill the hole sto size and insert the peg. The technique allows a larger gap between the peg and mounting that must be filled with solder. The problem is that there is an excessive amount of space around the head that allows the head to move, making proper alignment difficult.

A third technique is one that I recommend. First file the corners from the peg so the peg is octagon in shape. Now measure the peg diagonally across the flats in at least two directions, and select the appropriate drill size. This will create a hole size that is best suited to match the peg and provides the best fit.

Now that you have the hole drilled, it is time to consider the second problem. In most cases, the surface that the head attaches to is convex. When the peg is fitted into the hole, there is a gap between the base of the head and the surface of the mounting. Often you see these heads being soldered into place supported entirely by the peg. It needs to be pointed out that the peg is simply an indexing aid, and should not be used as a structural element.

This technique for getting the head to set flush to the surface is quick and causes a minimum disruption to the surface of the mounting. After the hole is drilled, use a 45 degree bearing burr and lightly chamfer the hole where the head will set. The diameter of the chamfer will need to be almost as large as the base of the head. This will allow the head to set into a pocket and let the prongs contact the surface of the mounting. This becomes an important point when soldering the head into place.

After the head is aligned, I like to turn the piece over and solder it in place from the back. Be sure to protect the piece from oxidation during soldering and flux the joint as well. I generally use two small chips (pallions) of solder, about 1mm by 1.5mm in size. A little extra solder is needed to fill in the chamfer and make a smooth fillet at the base of the prongs. Use a soft large flame if possible, and heat the mounting slowly using a on-off heating technique (one second on, one second off). Heating in this manner will allow the heat to travel through the mounting and into the head. You want to avoid heating the head directly, as it is very easy to overheat the prongs and damage the head. You also run the risk of forcing the solder to run up the prongs.

When the flux has dried and begun to turn clear, apply the solder and heat the mounting a little more. Watch the solder, and remove the heat when it begins to melt in to a small puddle. Turn the piece, and inspect the base of the head to see if the chamfer has filled and there is a fillet at the base of every prong. If not, flow the solder a little more. Remember, solder will always flow towards the hottest part. Any excess solder that needs to be removed should be on the back side of the piece and not the side of the prongs.

Try not to become complacent when soldering heads into place. Mounting the head securely is the most critical procedure for a bench jeweler and should not be treated as routine. Remember it is that head which is holding (usually) the most valuable part of the piece.