DIY - Forrest of Tabs

B&C makes a fairly ubiquitous grounding block, which is used in many many builds. It is a very good product, however I have not finished my wiring diagrams yet, but have already used up most of the 48 tabs on the cockpit side. I also don't need 24 on the firewall side, only a few. It is also $99 USD ($170 AUD). 

So i decided to do it myself! 

Off to the aviation aisle of Ebay once again, i got myself some 1.5mm brass sheet. 

I picked up some doulbe spade terminals, which are designed to be soldered to a PCB. These have a 4mm hole in the middle. 

I got some matching 4mm, aluminium countersunk pull rivets. These are 120 degree, but i have a countersink for that:

I also got some 1/4" brass bolts, washers and nuts. I had to get stainless lock washers. 

The all up cost was about 1/2 the B&C part, plus it allowed me to make as many tabs on each side of the firewall as i wanted. It also allowed me to have 2 brass grounding bolts for redundancy. 

I think the B&C parts have a larger bolt - i chose to use a 1/4" (M6) as this is the same size as whats on the battery - so it's clearly big enough!

These were big countersinks and almsost went through the material. To combat the pilot wandering and enlarging the hole, i countersunk using a backing piece of MDF.

I match drilled the 2 plates together on the firewall to #30, to make sure the holes aligned. I then up-drilled them to 1/4". 

A custom DIY plate, meant i could size it as i wanted - in this case i made it wider than the bolt spacing to fit 12 more tabs in. 

This is the forward tab. 

12 tabs firewall forward is plenty.

Even though the tabs were mechanically held in place, i chose to also solder them. I think the solder would have probably been strong enough - bit i've never been one to shy away from over-engineering. Plus it was fun!

The soldering iron wasn't going to cut it.

My first go was a bit average unti l i got the hang of it. 

I tested the resistance of every tab, just in case.

The second time was much better. 

Here they are installed.

I worked out how long the bolts needed to be, then cut them down.

Finally, i laid out a map of the new arrangement in my wiring diagram. I should hopefully be able to find the wire i am after at a later date if need be.