Finding the centre of a round bar can be difficult and time consuming. In this video I use a round bar centre finder which can be purchased on ebay for less than £6 http://fave.co/2sdV94Q
This enables you to find the centre of ant round bar, tube or pipe easily and quickly.

If you want to find the exact centre of the end of the bar you can do that using a bell punch (if you don’t have access to a centre lathe) https://www.youtube.com/watch?v=PssrSGRxNk8