[TheForge] slit & drift question

[Dave Mudge]

Dear TheForge,
I have a couple questions that I think some of you my have answers for.
I have a job coming up where I will have to pass 1/2" square pickets
through 3/4" x 1-1/2" flat bar.
I want to use the split & drift method.
1. How long does the split have to be to be in order to drift it out
to 1/2" square? even through 3/4" flat bar?
2. What is the best material that may be commonly found in a machine
shop to make the splitting chisel from?

thanks in advance,
dave mudge