I'm in Brisbane. Send me a PM. I might be able to help or if you are nearby , you can come and check out mine. Don't ask me how long it took to design. I was like you once.
The best solution (and the cheapest) today is without doubt the Linuxcnc Plasmac configuration.
I do have some Mesa cards here I could be convinced to part with. They with Linuxcnc will beat any THC hands down.
I have dual linear rails across the gantry (X)
and single 25mm rails on each side of the table
I actually looked at the gantry weight the other day. The second 15mm rail is hard to beat weight wise but next time round i might be convinced to run a combined gear rack with the V rail built in from TEA transmissions but I have not priced it.
If you have some data sheets and torque curves, I might be able to let you know if those motors will work OK.
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sorry link PlasmaC User Guide