Nut Size?

[BaDaBooM]

Thank a lot, that would be a much better option, will end up an expensive half nut. lol.
thanks for the links.

If it doesn't have to be a hexagon nut you can use the small threaded ring that comes with some 510 connections.

https://www.fasttech.com/p/1678700
510 to 510 Short Adapter / Battery Connector With Nut

 

[pez]

Right girls back to the kitchen there's washing up to be done. Oh, and two sugars........