fix and fit

Repairing Rivet Hinges

Alex Yoho, ABOM

For many years plastic frames had hinges that were attached to the frame front and temples with rivets. They were almost completely replaced by hidden hinges in the 1970s and 1980s.

With today's retro and techno looks, however, rivets are back.

REPAIR METHODS

There are several methods one can use when tightening or replacing these types of fasteners.

■ PEENING. Traditionally, rivets are peened—that is, taking a hammer and mushrooming the end of the rivet until the wire presses against the hinge plate to hold it securely.
This requires a polished anvil to provide a solid resting point for the face of the rivet or a shield to prevent it from pushing out of the front.
■ STAKING PRESS. A staking press has an anvil (and sometimes many) and a point holder that are connected by gears to a handle, giving the operator tremendous pressure in one concentrated point. The points are interchangeable and can accomplish other operations such as pressing out broken screws or removing existing rivets.
■ MANUAL OPTIONS. There are also more manual staking sets that guide the points and have an anvil, but require a hammer rather than handle to drive the points.

BASIC STEPS

Regardless of tools used, the basic method is the same.

■ REMOVAL. Remove broken parts by grinding or filing off the original mushroom of the old rivet and pushing it out using the pin punch point.
Set it into the hole in the anvil, then swing the fork up on top of the front or temple from which you need to remove it.
Finally, lift up on the lever until the pins are extracted. Sometimes, the rivet can simply be pushed partly out and gently grasped with a pair of cutters.
■ REASSEMBLY. Assemble the same way it came apart. Once reassembled, the assembly should be pressed to tighten things up and ensure that shield and flush rivet heads are embedded into the plastic face of the frame.

The proper point to compress everything together will be a cylinder with a flat spot toward the business end to clear the hinge barrels and two milled slots to accept the rivet pins. Cut off all but about 1.5mm from the hinge plate of the new rivet.

The last step is to peen (or mushroom) the ends of the rivets that extend from the hinge plate. With a hammer, buck the finished side of the rivet or shield firmly against the anvil, then strike the rivet straight-on. Or, mushroom the end with a flat hammer. Strike around the edge at a slight angle to deform the metal into a rounded cap.

When using a staking set, use the point with a cupped end, keeping the point perpendicular to the hinge plate. EB

1. REMOVAL: If pins get stuck in the plate, remove them with the staking set's adapter.
2. REASSEMBLY: A highly polished anvil will help as it will not scar the surface of the frame.