One of the reasons to have the "centring bar" sprung is one does not have to keep adjusting the tail stock to keep the correct amount of force applied. Makes life easier 
One can use just a straight bar - say silver steel (drill rod) 10/12 mm diameter. A point at one end and a centre drilled hole at the other end, suitable to take your dead centre. Remember to keep adjusting it
when in use.
Dave
One can use just a straight bar - say silver steel (drill rod) 10/12 mm diameter. A point at one end and a centre drilled hole at the other end, suitable to take your dead centre. Remember to keep adjusting it
when in use.Dave