I am planning on building a 5 axis cnc machine, most boards for cnc machines are either really expensive or use parallel ports,
is it possible to use the 2 extruder connectors for the other 2 axis's?
So, Smoothie firmware does not have -true- 5-axis support. It's planned though.
The best you will be able to get is 3-axis support, with two additional slaves axes.
That will do what you want, it just won't be as perfect planning/speed-optimisation-wise as a true 5-axis setup.
Right now I think the code needs a few modifications to actually support the two additional axes to function simultaneously.
Contact me at moc.liamg|ruhtra.flow#moc.liamg|ruhtra.flow when you start wiring up your machine and I'll help you with the configuration, it's not much.