In the second part of his series on frame adjustment, MURRAY O’BRIEN covers the most salient practical points that differ for various frame types and materials.
In the practice of frame adjustment, the frame material type will ultimately determine the methods and limitations.
Frames are generally divided into: Metals – stainless steel, monel, nickel silver, pure titanium, beta titanium, aluminium. Plastics – cellulose acetate, TR90, cellulose propionate, Optyl, SPX (Silhouette).
The following are some basic instructions to solve the most common issues.
1. Distance between temple tips too wide – There are two choices to resolve this: bend at the bridge, or where the temples attach to the rim. For acetate frames, warm the bridge with an air heater ensuring it only targets the bridge. There’s a risk of damaging multicoats if lenses near the bridge get too hot; potentially an expensive mistake. Once softened enough, hold the frame with the back facing you and thumbs each side of the bridge on the back of the lenses. Bend the frame to increase the facial curvature bringing the temple tips closer.
To bring in the angle of the temples on plastic frames, the frame front near the temples can be gently heated to soften the plastic and then, by pushing the heated area on a bench top, the angle can be brought in a little. Don’t apply too much heat as this can loosen concealed joints.
For metal frames, the most common method is to use one or two pairs of inclination pliers. Slip the metal conical part of the pliers between the rim and in front of the temple joint with the plastic part on the outside of the frame. Hold the frame front near the joint and bend in. Metal frames can also be adjusted at the bridge to increase the frame front curvature. Place your thumbs on the back nasal top corner of the frame and apply little pressure to bend the bridge in the middle.
2. Distance between temple tips too narrow – For acetate frames there’s the choice of either bending the frame at the bridge or filing the temple ends where they intersect the frame front. Use a rubber bench block to rest the frame while carefully removing material from the temple end whilst trying to maintain the original angle. Be careful to only take off a small amount and constantly check until the desired temple angle is achieved.
If the frame has a lot of facial wrap due to high plus lenses, the first option may be to heat the bridge and flatten the frame. If this doesn’t widen enough, the next step must be to file the temple ends.
For metal frames, inclination pliers can be used as above, but to bend the temples out. Observe the facial wrap of the frame. If there’s more than necessary, flatten by a gentle bending at the bridge first.
3. Adjusting for straightness on the face – if the frame doesn’t align with the eyes laterally, then one temple will need to be bent up a little and the other down. The technique to achieve this will depend on the frame construction.
Metal frames that are fine enough to bend in front of the temple attachment should be adjusted using parallel pliers.
Plastic frames that have a single charnier joint can be bent at the joint by applying pressure up or down on the temple itself by hand. When frames have multiple charnier joints they cannot be effectively adjusted, so the only option may be to twist at the bridge to achieve the desired difference in tip height. Although not ideal because the lens tilt will be different, it’s better than glasses that aren’t straight laterally.
There’s an onus on frame producers to ensure products can be adjusted adequately for good anatomical fitting. Unfortunately, this often isn’t the case, so beware.
4. Temple tips behind ears – whether metal or acetate, heat with either an air heater or hot box (heated beads). Warm the plastic just enough so it is pliable. Straighten the tip if the bend needs to start in a different place. Only use your fingers to bend tips, it would be rare for tools to be required. Using two hands, support with the thumbs and use the index finger to bend the tip around.
For the mastoid process, use fingers and thumbs again as there really aren’t tools specifically designed for the job. Sometimes it’s hard and frame benders (meniscus pliers) can be used.
ABOUT THE AUTHOR: Murray O’Brien owns Designed Eyes in Rosebud, Victoria, where he works in full retail optics. He is also past president of the Australian Dispensing Opticians Association (Vic) and has previously worked in lens fitting work, specialising in rimless.