Secondary base finished

Just got in from the garage.  Spent a couple of hours drilling and tapping the holes in the secondary coil and the bottom disc.

The eight holes around the perimeter are tapped to accept 20mm M4 bolts which will pass through corresponding 4mm holes in the secondary coil. The other eight holes started as 7mm plain holes and were then tapped to M8. They will be used to bolt the secondary coil down to the base.

The holes were drilled with the disc in situ inside the secondary coil. The drill size required is 3.3mm. After drilling the components were separated and the disc tapped to M4. The 3.3mm holes in the secondary were opened up to 4mm.

Here you can see the base disc bolted inside the secondary coil. Think it looks great and, as usual, completely over engineered.

I have used nylon bolts, not sure if it would be OK to use metal so opted for nylon.