Clamp on strike rail earth connector

Today I fabricated a mock up clamp to earth the strike rail. I started with one of the copper electrical lugs that I bought from Teslastuff.com.

You will not find these listed anywhere on the website or on the Teslastuff eBay shop you will have to email the owner Alan and ask for a price. They are far better quality than anything I have found available in the UK. If you know different drop me an email. I used a length of aluminium 1/2" square rod to make the pieces that form the clamp.

These pieces started off as one block which I drilled with a 12mm bit to form the internal curve and a 6mm bit to form the bolt hole. I used a file to produce the curve on the other end. The block was then cut down the middle using a slotting saw on the milling machine. The two pieces were then clamped back together in a vice on the milling machine and then a 4mm hole drilled exactly on the interface of the two pieces. Using a perfectly flat surface and a piece of fine glass paper I worked the adjoining surfaces this makes the 4mm hole slightly smaller so it clamps tight on the 4mm strike rail. 

Here are the assembled pieces. Straight away I spotted an improvement that could be made when fabricating the actual unit, if I put threads on the bolt hole on the top aluminium clamp plate I can dispense with the nut and use a shorter bolt. Also the actual unit will have copper clamping plates to reduce resistance (aluminium 2.7, copper 1.7ohm.m).

I will mount the finished clamp the other way up than shown above. There will be no need to move this clamp once it is in position on the strike rail. But, obviously, access to the grub screw will be needed to clamp the grounding wire.

With the improvements mentioned I think this clamp will do very nicely. Off to eBay to get some copper square rod.