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Spider Assembly to FrameStrength requirements for this bond vary dramatically.At the low end of the stress scale are drivers usinga small voice coil, with modest cone movement togetherwith a large diameter spider. Under these circumstances,the stress on the bondline is minimal, and the adhesivecan be selected for economy or dispensing ease, or both.At the high stress end of the scale are large coil and largeexcursion drivers, particularly those with smalldiameter spiders. In this type of driver, the adhesives aresubjected to simultaneous shear, cleaving, peel andthermal stresses. The bond must be slightly flexible yetaggressive and durable.Priming the surface of the frame with a Loctitecyanoacrylate primer will ensure the quickest possiblebond. A bead of low-viscosity cyanoacrylate, such as 401applied to the edge of the spider, will wick into the bondline,developing good handling strength in about20 seconds. If oversprayed with a Loctite ® accelerator,it is even faster. Both adhesive and accelerator make foran almost invisible bondline.Some spiders have a surface coating, such as moldrelease, that can delay or even entirely inhibit the cure ofcyanoacrylates. A simple remedy is to wipe the bore ofthe spider with a Loctite ® accelerator, such as 7452. Ifprimers (such as PRISM ® Primer 770 AdhesionPromoter) are being used, they should be applied tosurfaces other than the spider, as they may wick into thefibers and not evaporate fast enough for convenientassembly. The phenolic resins used in manufacturingspiders varies from slightly base to slightly acidic, andthe pH factor can dramatically influence the cure speedof cyanoacrylates.On drivers using plastic frames, the spider to framebond can be accomplished by direct heating of the bondline,causing the plastic to reflow into the spider. This isvery quick and economical, but makes rework of anyQC rejects impractical.Recommended products for the Spider Assembly to Frame:Loctite ® Cyanoacrylate Adhesives 401 or 410.See detailed Product Information on Cyanoacrylates on pages 22 and 23.11Assembling Speakers with Loctite® Adhesives