Temple Break Location
While both metal and plastic temple arms can be broken somewhere in the length of the arm between the end of the hinge attachment area and the tip, plastic temple arms pose a number of mechanical and cosmetic additional problems that require knowledgeable solutions and skilled repair.
While many non-spring hinge attachment points on modern and vintage temple arms are well affixed to the arm with rivets or thermo set anchors, even those with a center rod for reinforcement have an Achilles heel just past the end of the hinge plate where they tend to fatigue and snap off.
Vintage Plastic Frames vs. Modern Plastic Frames
It is not uncommon for an excellent condition vintage plastic frame from the 60s to the 80s come in with a clean break at the point where the hinge plate is affixed to the temple arm flank. Modern frames exhibit the same problem where the thermo set anchor area of a modern well made hinge affixes to the temple arm and develops a clean straight break right across the arm just past the attachment point.
This breakage is easy to understand once you recognize that all of the strain of pulling the temple on outward to remove the frame puts all the stress at the unreinforced area just past the end of the hinge attachment area.
Accordingly, when looking to execute an excellent repair, one needs to address the unreinforced nature of this break line. The solution is to introduce a pair of heavy gauge metal reinforcement rods inside the temple arm beginning at the end of the blind shut face lip of the temple arm, passing through the hinge block area, and extending as far as is practically possible.
We use a pair of 60 gauge model rods 100 millimeters long. The rods are acid etched in nitric acid to put a mechanically aggressively course surface on the rods. We then coat them in a catalyst activated resin and then they are slid into the drill holes.
An alignment rack must be used to ensure that the drilling passes centrally through the temple arm body, clears the hinge rivets or thermoses anchors, and extends out through the break and on into the sold body of the temple arm.
This repair leaves the temple arm far stronger that it was when new, and we have had units that come in broken, go out and remain in daily use for a decade.
This is a classic example of taking a design flaw of a frame, and turning around to being a strong point with no visible cosmetic flaws to the surface of the frame.
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Framefixers, 4736 Onondaga Blvd, PMB 106, Syracuse, NY 13219