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Step 4Surround finishing and attachment
The coating of the stretch cotton interlock material can use med viscosity 2 part silicone thinly applied with a brush, this works the best, as it has a longer pot life, and flows somewhat, but costs more. If you want to economize try plumbing air set silicone (in 300 gr cartridge or tube) applied very sparingly with a putty knife but you have to work quite quickly and the surface finish tends to be uneven in early attempts.
VENTILATION and Plastic gloves are useful precautions.
Consult the web for suitable release agents, or can try cling wrap on each side of the mould. While setting align the 2 parts of the mould as they were separated originally. Apply enough pressure evenly, but not so much as to risk cracking the plaster. A No of large spring clips can suffice, or heavy weight (10's of KG for a 10 - 12 in) on a flat surface. Leave overnight or longer for 2 part, trim to size with sharp scissors, or trimming blade. Assess the outcome for weight, (as light as possible generally, mass similar to orig foam is achievable) appearance and no later leaks when held up to light, a minute dab of silicone will do if there's the odd one. PVA won't adhere to silicone hence coating material on non gluing side only. Silicone and a few special glues will adhere to silicone adequately but future removal from paper cones is problematic. If you coated the wrong side of the material, Silicone could be used on driver frame for the outer surround after centering has been fully checked. Cardboard or cork gaskets on the frame need case by case planning from the outset re salvage in one piece and later re-attachment.
The surround below was rejected and shows what happens when too much is applied it permeates to the gluing side and had excessive mass compared to a foam one. Very old heavier rubber surrounds can split eg Philips 10100 and 12100 so this could be as a replacement if the gluing aspect has been taken into account. Full range drivers with very light paper cones like Philips AD4200M or 9710 with a corrugated paper surround, also have a small Xmax, use of a roll surround isn't recommended. But it has been done by cutting off the old surround and using one with a narrow roll.
Another instructable "How to refoam your woofer" gives extra detail of surround attachment.
Proceed as per web guides for driver attachment, noting correct orientation, ie roll up or down, glued to upper or lower edge of cone etc. Ensure adequate cone travel with no rubbing. Recheck driver ohms with a multimeter and Fres if required, before system re-assembly.
Sit back and enjoy or collect beer dues.
VENTILATION and Plastic gloves are useful precautions.
Consult the web for suitable release agents, or can try cling wrap on each side of the mould. While setting align the 2 parts of the mould as they were separated originally. Apply enough pressure evenly, but not so much as to risk cracking the plaster. A No of large spring clips can suffice, or heavy weight (10's of KG for a 10 - 12 in) on a flat surface. Leave overnight or longer for 2 part, trim to size with sharp scissors, or trimming blade. Assess the outcome for weight, (as light as possible generally, mass similar to orig foam is achievable) appearance and no later leaks when held up to light, a minute dab of silicone will do if there's the odd one. PVA won't adhere to silicone hence coating material on non gluing side only. Silicone and a few special glues will adhere to silicone adequately but future removal from paper cones is problematic. If you coated the wrong side of the material, Silicone could be used on driver frame for the outer surround after centering has been fully checked. Cardboard or cork gaskets on the frame need case by case planning from the outset re salvage in one piece and later re-attachment.
The surround below was rejected and shows what happens when too much is applied it permeates to the gluing side and had excessive mass compared to a foam one. Very old heavier rubber surrounds can split eg Philips 10100 and 12100 so this could be as a replacement if the gluing aspect has been taken into account. Full range drivers with very light paper cones like Philips AD4200M or 9710 with a corrugated paper surround, also have a small Xmax, use of a roll surround isn't recommended. But it has been done by cutting off the old surround and using one with a narrow roll.
Another instructable "How to refoam your woofer" gives extra detail of surround attachment.
Proceed as per web guides for driver attachment, noting correct orientation, ie roll up or down, glued to upper or lower edge of cone etc. Ensure adequate cone travel with no rubbing. Recheck driver ohms with a multimeter and Fres if required, before system re-assembly.
Sit back and enjoy or collect beer dues.
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