Ground anodized AL

[RVG8tor]

I have a terminal block under the front east. It is mounted with 2 screws into the gold anodized spar cap. I need a ground here and the simplest thing would be to put a ring terminal on one of the screws that holed the terminal tray in place. I now anodized aluminum is not as good a conductor as non-anodized but is it good enough of a ground for switches?

If anyone has used a screw or bolt into the anodized parts for a ground, how did this work out?

Thanks

[terrye]

I made several electrical grounds on the anodized wing spar. I used a rivet shaver bit (flat cutting end) in my micro stop countersink to make a flat spotface through the anodizing and just into the aluminum. If you do this be sure you make a guide for the skirt and clamp it to the surface as the flat shaver bit wants to wander as it contacts the surface. I then alodined the bare aluminum and used a -3 platenut and hex bolt for the ground bolt. It is important to use an aluminum washer in contact with the alodined aluminum surface.

Not sure there was much gained by using the structure as an electrical ground return path over running ground wires. Especially as I have fully epoxy primered the inside of my structure.

In the fuselage I am considering running dedicated ground wires instead of grounding to the structure.

[RV6AussieNick]

Any anodised surface has poor conductivity, to gain a good electrical bond you need to remove the anodised finish in that area, at work I use what we call a bonding brush, you could probably find it at yard store, its basically a wire brush that grinds away the finish, before assembly treat the area with alodine 600 if available to maintain the corrosion protection whilst still allowing the bond
Hope that helps.

[DanH]

Use a ground wire.

Carefully removing the anodizing under the ring terminal only guarantees conductivity at that one point in the electrical path, which now has to run across connections between a number of other (anodized?) parts.

Not at all the same as using a one-piece longeron as a ground path.

[RVG8tor]

Originally Posted by DanH

Use a ground wire.

Carefully removing the anodizing under the ring terminal only guarantees conductivity at that one point in the electrical path, which now has to run across connections between a number of other (anodized?) parts.

Not at all the same as using a one-piece longeron as a ground path.

Dan I finally came to the same conclusion, I will just run the wire and be done with it.

Thanks for all the input guys.