To try to upgrade the body of the metal detector search coil, you need to know the material from which it is made. It is known that this is a quite soft thermoplastic. Most often it is made of polystyrene or capron. But one thing can be a serious problem. The wire was filled with a rather rigid epoxy. From the course of physics, we can recall that the components have poor adhesion, in other words, "they are not friends." That is why, all wires coming from the enterprise are “doubtfully” connected.
After 1-2 years of active use, “creases” of resin are observed on the surface of the coil. You can also see the opening of the end face of the surface - this is a serious problem, due to which water gets inside. All attempts to fix this problem using epoxy will not solve it.
But there is a solution. At the initial stage, we make an artificial “breakdown”: with the help of an awl we make chips-“creases” in all possible places. Further repairs should be carried out in two stages. Initially, the “Droplet” glue is used to patch all the tracks. Packages of 3 g is enough for any coil. At the second stage, all “creases” are completely being hidden using epoxy resin. The glue used at the initial stage ideally fills all chips, dries and is drawn into the gap.
When carrying out repairs, pay attention to the fastener of the AKA coil to the rod; it must remain intact to avoid additional expenses.
The renewal procedure is completed. You don’t need to try especially hard - at the start of operation, the sand will “polish” all your shortcomings. Pay attention that now the working surface of the renovated coil looks like new.
What have you done? - The most important work on updating the surface of the coil, which was performed by the “droplet” superglue. This surface was protected by epoxy resin.
When shall you start repair? For this it is necessary to make an inspection of the surface of the coil. If you notice a thin filiform crack - it is your case. And one more thing: try to create conditions so that the resin dries gradually, not in a day, but in two or three days. It is necessary so that the repaired surface does not have any prerequisites for cracking.
And the last nuance again arises from physics: pouring with glue must be carried out on a warm coil - when it dries, it will fill the gap.