Frame Standard Alignment And Repairs PDF

FRAME STANDARD ALIGNMENT AND REPAIRS AUTHOR David Wilson: Brien Holden Vision Institute (BHVI), Sydney, Australia PEER REVIEWER Mo Jalie: Visiting Professor: University of Ulster, Varilux University in Paris THIS CHAPTER WILL INCLUDE A REVIEW OF: Frame Manipulation – Introduction Nylon Ja...

FRAME STANDARD ALIGNMENT AND REPAIRS AUTHOR David Wilson: Brien Holden Vision Institute (BHVI), Sydney, Australia PEER REVIEWER Mo Jalie: Visiting Professor: University of Ulster, Varilux University in Paris THIS CHAPTER WILL INCLUDE A REVIEW OF: Frame Manipulation – Introduction Nylon Jaw Pliers Angling Pliers Pad Adjusting Pliers Finger Piece Pliers Square/Round Pliers Standard Alignment Standard Alignment – The Steps Soldering Re-sinking a Joint Repairing the Bridge (acetate) September 2012, Version 1 Applied Optics Chapter 17-1  Frame Standard Alignment and Repairs FRAME MANIPULATION – INTRODUCTION The previous lecture looked briefly at the requirements for manipulating different frame materials. Plastic materials require heat, the type of plastic determining the temperature at which they should be manipulated (Figure 17.1A). Frame manipulation also requires the correct tools. This lecture will examine the main tools and then the techniques used for frame manipulation. Figure 17.1A: Plastic frame Figure 17.1B: Metal frame NYLON JAW PLIERS The padding at the mouth of the pliers helps to avoid marking the frame during adjustment. Some pliers have a pad that will have a groove in the centre to grasp a metal temple (Figure 17.2). FUNCTION Support the bridge during coplanar frame adjustment of rimless frames and/or whilst adjusting the nose pads. Figure 17.2: Nylon jaw pliers September 2012, Version 1 Applied Optics Chapter 17-2  Frame Standard Alignment and Repairs ANGLING PLIERS The structure of the pliers’ end allows for the gripping of a hinge joint (Figures 17.3A and 17.3B). THEY CAN BE USED FOR: Adjustment of the angle of the side tilt (temple open) Adjustment of the temple folding angle (temple closed) Supporting the hinge while bending the temple to adjust the angle of the side angle Figure 17.3A: Angling pliers Figure 17.3B: Adjusting hinge joint PAD ADJUSTING PLIERS The ends of the pliers are specifically designed to grasp nose pads (Figures 17.4A and 17.4B). FUNCTION: Adjustment of the splay angle (to the edge of the nose) and the frontal angle (to the vertical meridian) of the nose pads. Figure 17.4A: Pad adjusting pliers Figure 17.4B: Adjusting nose pads September 2012, Version 1 Applied Optics Chapter 17-3  Frame Standard Alignment and Repairs FINGER PIECE PLIERS The jaws of finger piece pliers do not close together but remain parallel and apart when ‘closed’. They have small depressions in the jaws to fit screw heads (Figure 17.5). FUNCTION: Adjustment of the angle of the side With the hinge closed, this pliers grips either side of the hinge screws or end-piece, rotating it until the appropriate angle is achieved. Figure 17.5: Adjusting angle of sides SQUARE / ROUND PLIERS The tapered (round) jaw of these pliers can fit into the narrow gap between the front and the joint of the frame. They can be used in conjunction with double-padded pliers (Figure 17.6). FUNCTION: Adjustment of coplanar lenses (X-ing) Adjustment of the angle of the side tilt Adjustment of the folding angle To bend metal with a rolling action, e.g. nose pad arms Figure 17.6: Round pliers September 2012, Version 1 Applied Optics Chapter 17-4  Frame Standard Alignment and Repairs STANDARD ALIGNMENT Standard alignment (Figure 17.7) is the process of manipulating a frame into a shape determined by the manufacturer. It should be done before fitting the frame to the patient and is normally carried out by the frame manufacturer in the first instance and by the lens laboratory after fitting the lenses to the frame. If the frame is in perfect alignment then any fitting errors that are apparent when the frame is placed on the patient are due to the patient’s asymmetrical features. Standard alignment must be carried out in the correct sequence because certain adjustments may impinge on previous steps if carried out later. Figure 17.7: Standard alignment September 2012, Version 1 Applied Optics Chapter 17-5  Frame Standard Alignment and Repairs STANDARD ALIGNMENT – THE STEPS The frame should be checked to ensure that it is symmetrical when viewed from the front. It should then be viewed from above to ensure that it has the correct facial wrap (Figure 17.8). A ruler can be held across the back of the frame, touching at the temple joints. The front should exhibit the same gap at both sides of the bridge. 1. CHECKING THE CONTOUR OF THE FRAME FRONT Figure 17.8: Checking facial wrap The frame should also be checked from above to ensure that both lenses are in the same plane (allowing for facial wrap) and that one lens is not twisted (often referred to as X-ing) or in a plane anterior to the other. Figure 17.9 shows a case of X-ing. 2. CHECKING THAT THE LENSES ARE IN THE SAME PLANE Figure 17.9: Checking the planarity of both lenses (in this case, one is twisted) The let-back is the angle between the opened temples and the frame front measured from inside the temples. This angle should be about 95° (Figure 17.10). That is, the temples should open slightly wider than parallel. 3. CHECKING THE ANGLE OF THE TEMPLES (THE LET-BACK) Figure 17.10: Checking the angle of the temples September 2012, Version 1 Applied Optics Chapter 17-6  Frame Standard Alignment and Repairs STANDARD ALIGNMENT – THE STEPS (cont.) The frame with the temples opened should be viewed from the side to ensure that the temples are in the same plane. That is, that they have the same angle (Figure 17.11). 4. CHECKING THAT THE TEMPLES ARE IN THE SAME PLANE (ANGLE OF THE SIDES) Figure 17.11: Checking the angle of the sides The temple ends should be compared to ensure that they are symmetrical. Standard alignment involves aligning the frame to an ideal shape, rather than to suit a particular person (Figure 17.12). Frame adjustment, which will be considered later, will address the issue of patient asymmetry. 5. CHECKING THE ANGLES OF THE TEMPLE ENDS Figure 17.12: Checking the angle of the temple ends (Often referred to as the ‘four point touch’). The frame should be placed upside down on a flat surface (Figure 17.13). If the frame is correctly aligned the frame should rest on the surface without rocking. This step simply indicates that one or more of the first five steps has not been carried out correctly. It will not indicate which step or steps are at fault. Therefore, if the frame rocks the first five steps should be carried out again in their correct order. 6. CHECKING THAT THE FRAME CONFORMS TO A FLAT SURFACE Figure 17.13: Four point touch September 2012, Version 1 Applied Optics Chapter 17-7  Frame Standard Alignment and Repairs STANDARD ALIGNMENT – THE STEPS (cont.) The temples, when folded, should fold so that they are level and close to horizontal (Figure 17.14). If they are angled down when closed they should be adjusted while in the closed position and step 4 should be re-applied to make sure that the angle of the side has not been affected. If the folding angle is too shallow the temple ends can rub on the lenses. On the other hand, if the folding angle is too deep the spectacles will not fit in their case. 7. CHECKING THE FOLDING ANGLE Figure 17.14: Checking the folding angle 8. CHECKING THAT THE JOINTS ARE The temples should be relatively easy to open and close but should not close with gravity NOT TOO TIGHT OR or a light shake. TOO LOOSE Finally, the overall appearance of the frame should be checked (Figure17.15). This will include looking for scratches or marks on the frame. These final two steps represent an overall quality control check. 9. CHECKING THE OVERALL QUALITY OF THE FRAME Figure 17.15: Checking the overall appearance September 2012, Version 1 Applied Optics Chapter 17-8  Frame Standard Alignment and Repairs SOLDERING Soldering is the use of a soft metal that is melted to joining two other pieces of metal. It can be used to join a broken bridge in a metal spectacle frame or re-attach a pad arm. 1. Remove lenses and plastic trims, to prevent burning. It is not necessary to remove temple end-pieces, however, plastic pads should be removed if a bridge or pad arm is being soldered. Figure 17.16A: Preparing the frame for soldering 2. Clean the area to be soldered with fine sandpaper & a solvent. It is important to remove any grease or dirt to ensure a strong solder (Figure 17.16A). 3. Hold the pieces together using a jig with clips if available. If being held by hand, wear gloves and/or hold the pieces as far away from the flame as possible. The blue flame of the gas is extremely hot. 4. Apply flux (borax). Flux acts as a catalyst so that the metal Figure 17.16B: Applying the solder and flux will bond. Flux is normally a whitish paste which needs to be kept moist (Figure 17.16B). 5. Adjust the flame of the mini gas to produce a blue flame. 6. Hold the metal part to be joined in the blue flame and apply the solder. Solder will normally be supplied as a long thin wire. It is available in silver or gold (Figure 17.16C). 7. Apply heat until the solder runs into the joint. Remove the solder once enough has run into the joint. Figure 17.16C: Soldering the frame 8. Remove the frame from the heat and place it in a mixture of diluted sulphuric acid (mix about one part acid to eight parts water, applying the acid to the water). The sulphuric acid will help to prevent the solder from blackening. 9. Clean and buff the frame. Care should be taken when buffing metal frames to avoid catching the frame in the buff (Figure 17.16D). Figure 17.16D: Cleaning and buffing the frame 10. Inspect and re-assemble (Figure 17.16E). Figure 17.16E: Re-assembling the frame September 2012, Version 1 Applied Optics Chapter 17-9  Frame Standard Alignment and Repairs RESINKING A JOINT The metal joints in plastic (cellulose acetate) frames will occasionally be torn from the plastic with excessive force. By heating the joint, or a new joint if the first joint was broken, it can be inserted into the plastic which softens under the heat of the joint. 1. Remove the broken joint with the heat pliers (Figure17.17A). Take care not to burn the frame with excessive heat. 2. Clean the frame and apply a small amount of acetate if necessary. Figure 17.17A: Removing the broken joint 3. Hold the new joint in position with the heat pliers. Ensure that it is not angled in either plane. 4. Apply heat to the pliers and press the joint into position (Figure 17.17B). The heated joint will cause the acetate to melt around the base of the joint. 5. Release the joint once it is in position. Figure 17.17B: Applying the new joint REPAIRING THE BRIDGE (ACETATE) 1. Drill a small hole into the bridge on both sides and in corresponding positions (Figure 17.18A). 2. Cut a piece of rigid wire about 2mm shorter than the total of the holes. A straight section of a paperclip will serve the purpose. 3. Place the broken ends of the bridge in a shallow dish of acetone (Figure Figure 17.18A: Drill a small hole into the bridge on both the sides 17.18B). The acetone will begin to melt the acetate frame 4. Once the surface becomes quite soft, insert the wire and push the bridge together. Do not use too much force. There should be a slight ridge caused by the surfaces being pushed together (Figure 17.18C). 5. Set the frame into position by placing it in a soft material such as blu tack or plasticine which will allow it to set. It should be left for over 12 hours. Figure 17.18B: Place the broken ends of the bridge in a shallow dish of acetone N.B.: This repair will not work on all plastic materials, only those for which acetone is a solvent. Figure 17.18C: Insert the wire and push the bridge together September 2012, Version 1 Applied Optics Chapter 17-10  Frame Standard Alignment and Repairs SUMMARY IMPORTANCE OF STANDARD ALIGNMENT Accurate standard alignment ensures faster and more accurate adjustment to the features of the patient (this will be covered in a later lecture). While standard alignment is normally carried out by the laboratory when the spectacles are made, it should be checked by the practitioner before delivering the spectacles to the patient. LIMITATIONS OF REPAIRS While frames can be repaired, using the methods described in this lecture, the repaired frame is not as strong as it was originally. This is particularly true of the plastic bridge repair and solders to metal frame bridges, since the bridge of the frame is generally under the greatest stress. Frame repairs are best considered as a temporary measure and this should be emphasised to the customer. BIBLIOGRAPHY Jalie M. 2003. Ophthalmic Lenses and Dispensing. Butterworth Heinemann, London. Jalie M. 1984. Principles of Ophthalmic Lenses, ABDO, London. Wakefield KG and Bennet AG. 2000. Bennett's Ophthalmic Prescription Work, Butterworth-Heinemann. Brooks CW and Borish IM. 2006. System of Ophthalmic Dispensing. Butterworth Heinemann. Brooks CW. 2005. Essentials of Ophthalmic Lens Finishing. Butterworth-Heinemann. Wilson D. 2006. Practical Optical Dispensing 2nd Edition. Open Training and Education Network, Sydney. Wilson D and Stenersen S. 2002. Practical Optical Workshop. Open Training and Education Network, Sydney. September 2012, Version 1 Applied Optics Chapter 17-11