Sturdy and Fast all Steel CNC , my first build

[JAZZCNC]

Hi,

Well the design looks strong but you have some quite major conflicts going on here.?

First the weight of the gantry really means your on the very edge of needing Servo's not steppers.!

Next because your using R&P then efficiency is very low so larger Nema34 motors will usually be needed to deal with this and the weight of the gantry.
The G540 is limited to 3.5A and 50V which isn't nearly enough for Nema 34 motors which you'll need at least 75Vdc or higher and more amps.
Nema 23 motors (even low inductance) just will just not be able to handle the Inertia this gantry's weight will put on them. Plus combined with R&P they will also struggle to give fast acceleration with that heavy gantry which you'll need for 3D work.
Even with larger Drives and higher 70Vdc voltage nema23 motors won't work with this weight gantry and high speed requirements.

Really I wouldn't recommend R&P for a machine this size and with your requirements for accuracy and 3D work, Ball-screws are the only way to go.!!. . . .You'll seriously regret using R&P.

Regards Steppers or servo's then I'd say lighten the gantry 20-30Kg and use Nema 23 motors running on 80Vdc drives with 70Vdc power supply and connected to 10mm pitch ballscrews.

If you don't lighten gantry then I'd say choose Servos has they will handle the inertia and speed much better.
Larger Nema 34 motors will handle the inertia at slower speeds but not do so well with the combination of speed and inertia has because they spin considerably slower than Nema23 motors they will struggle with reaching higher speeds anyway and the torque will be low at high speeds so with heavy gantry will struggle to handle inertia when changing direction.

So Above 80KG gantry at speed will need servos.

With Electrics in base of machine then I wouldn't recommend it has vibrations tend to loosen wires and don't mix well with sensitive electronics.!!

The 4mm steel will be fine for threads with rails.!