Cavity shielding technique?

[cab32]

All the instructions I see for shielding pickup and control cavities involve cutting foil sheets to fit the cavity bottom, then cutting separate strips for the sides and then soldering to achieve electrical continuity. Is there some reason why the foil isn't formed to fit both the sides and bottom in one continuous piece to eliminate the need for soldering the shield sides to the the bottom? What am I missing here?

[UnklMickey]

cab32 said:

...What am I missing here?

just a little bit.

square and rectangular shapes would work well with a single single piece for the bottom and sides.

for instance, a cube shaped cavity would require a single piece 3x the length and 3x width of a side.

1x squares would be removed from each corner, leaving a cross.

the top, bottom and sides would be bent upward, and the seams joined.

cap the whole thing off with a cover (like a shielded pickguard) and you're done.



the problem comes with complex shapes like curves.

there isn't enough material around the inside of a curve to make the vertical wall. and too much material on the outside of a curve.

the outside would require numerous cut be made and the pieces could overlap, when bent upward.


depending on the shape of cavity, it might make more sense to carefully plan out the shielding and make it mostly out of a single piece.

in other cases, it would be simpler to make a bottom, and a long continuous strip for the vertical wall.

sometimes the best choice is a composite of the two methods.

and other times, with complicated shapes and angled wall, you just "wing it".



unk



BTW: welcome to GN2!


and keep on thinking those kind of thoughts, and asking those kind of questions.

sometimes the answer is "because nobody thought to do it that way". then you're onto something better.

[JohnH]

unklmickey said:

the outside would require numerous cut be made and the pieces could overlap, when bent upward.

The first one I did was like that, using thick foil, on a 'blob' shaped cavity.

I made a cardboard template of the cavity base, then copied that onto foil and drew another curve outside of it by a distance equal to the cavity depth. Then I sliced this outer zone radially at about 1" centres. The sides were then bent up and joined at the top and the whole thing could fold down into the cavity, in one electrically continuous piece. I did it that way because I was using thick Al foil and cant solder it. The 'strip' and 'base' method with copper is probably better.

cheers

John

[cab32]

Thanks for the comments. Now that I have started with some heavy copper foil, I understand the problem of curves. Turns out at least with an old style strat body pickup rout pattern, seperate bottom and side peices result in the least work and fitting.