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After winding up a small 5" search coil, had a small of problem of not having a shell that small to use.
So I improvised, which you can too.
Found a polyethylene juice container at the thrift store and another storage cup. Cut the top section off that would be used as the outside of a temporary mold. The storage cup was filled with coins 9for weight) to be used as the center of the mold.
The juice container top section was hot tack glued onto a piece of formica top. Then some painters tape was placed around the outside to help prevent or control leakage of epoxy. Some wax was rubbed onto the formica top to prevent any sticking and easy release.
Then poured a first layer of epoxy into the mold. Let it set up for 6 hours. Then carefully dropped the wound coil over the cup and into the epoxy. Pressed it into place a bit. Set the coil strain relief into position, held in place with mixing sticks.
Mixed up some more epoxy and filled in the top layer. I ran a little short of epoxy, so my strain relief was still somewhat exposed over the top of the epoxy. No big deal. Would take care of that later.
After 26 hours of curing, pulled the tape off the mold, took out the storage cup and then removed the juice container top off the shell. What came out was a rough coil. Sanded the area by the strain relief and filled it in with sculpting epoxy.
Waited about 8 hours for the sculpting epoxy to cure...
Grabbed several files and sandpaper the coil was trimmed and shaped to the final look.
Took some hobby wood that was lying around and made two search coil rod ears. They were fitted into place, then used JB Weld to glue them to the coil.
After this dries, going to laminate a layer of fiberglass cloth with epoxy to the sides of the ears that will also help anchor them to the coil. Thinking about spraying some automotive bed liner on the shell to add a protective layer top and bottom.
Hope this helps anyone without the appropriate shell...........
So I improvised, which you can too.
Found a polyethylene juice container at the thrift store and another storage cup. Cut the top section off that would be used as the outside of a temporary mold. The storage cup was filled with coins 9for weight) to be used as the center of the mold.
The juice container top section was hot tack glued onto a piece of formica top. Then some painters tape was placed around the outside to help prevent or control leakage of epoxy. Some wax was rubbed onto the formica top to prevent any sticking and easy release.
Then poured a first layer of epoxy into the mold. Let it set up for 6 hours. Then carefully dropped the wound coil over the cup and into the epoxy. Pressed it into place a bit. Set the coil strain relief into position, held in place with mixing sticks.
Mixed up some more epoxy and filled in the top layer. I ran a little short of epoxy, so my strain relief was still somewhat exposed over the top of the epoxy. No big deal. Would take care of that later.
After 26 hours of curing, pulled the tape off the mold, took out the storage cup and then removed the juice container top off the shell. What came out was a rough coil. Sanded the area by the strain relief and filled it in with sculpting epoxy.
Waited about 8 hours for the sculpting epoxy to cure...
Grabbed several files and sandpaper the coil was trimmed and shaped to the final look.
Took some hobby wood that was lying around and made two search coil rod ears. They were fitted into place, then used JB Weld to glue them to the coil.
After this dries, going to laminate a layer of fiberglass cloth with epoxy to the sides of the ears that will also help anchor them to the coil. Thinking about spraying some automotive bed liner on the shell to add a protective layer top and bottom.
Hope this helps anyone without the appropriate shell...........
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