Cnc wiring!

[JAZZCNC]

Thanks for that jazz.
Stepper drivers and psu's.
I'm going to be running nema 23's 425oz 3amp. What stepper driver should I use? Some are rated up to 3amp and some more and then they are rated voltage wise. Until I decide on steppers I'm assuming I should hold off on psu's.
I see some people use 2 psu's driving two motors each. Can I just use one for the motors and a 5v supply, or is it best to use one for motors, another lower rated for fans etc and a 5v for the board?

Mick

Well it's little more complex than just amps.?
Not all steppers are equal and even thou may be rated same size doesn't mean they will perform the same. Inductance rating of the motor is very important to how well stepper will perform with a given voltage.

For instance, motor with high inductance will spin much slower than one with low inductance using the same voltage.
So if the steppers you buy have high inductance it will mean you'll need to run them with much higher voltage to get the same speed as Low inductance motor.

Then you have how the motor phases are wired. Steppers tend to come in two flavors. 4 wire and 8 wire.
4 Wire motors are less flexible because their phases are predefined at the factory. Often their phases will be series wired.
This means they will require much more voltage to achieve high speeds. Parallel wired motors, on the other hand, will reach same speeds with less voltage.
Often you'll find Series wired motors on Mills or machines which require high torque but less speed. This is because they produce higher torque lower down the rpm range but quickly lose torque as RPM's rise.

Parallel wired phases, on the other hand, give less low down torque but carry more torque higher up the rpm range. This is why parallel is preferred for routers.

8 wire motors allow Either series or parallel phases so again are preferred and easier to find than 4 wire parallel wound motors.

Voltage is the key to getting speed from stepper but at same time too much voltage can lead to over heating and resonance issues.
So this brings us back to inductance and why it's important. Lower inductance means higher speeds can be got with less volts and less volts equals less motor heating, less resonance etc.

So to answer your question about Drives and PSU will require knowing more about the motors. Would also help to know more about the machine spec and what you intend to do with it.

However if you want proven setup which works with most small to medium sized routers then the spec below works great.

Nema 23 3.1Nm 4.2Amp 8 wire motor wired parallel. Ideally with Inductance around 3mh or less.
Digital drives with voltage between 70-80V. Leadshine AM882 are great drive.
PSU with 60-68Vdc output depending on drive voltage. Current will depend on #motors and PSU type.

Now the Psu is little more involved because several types but the best solution by far is unregulated Toroidal PSU. It's gets little involved to why best but trust me this is the best setup for stepper motors. If really want to know why I will explain.

The reason you have probably seen people use 2 psu's is because they have bought off the shelf units which have limited current output so not enough to power 4 motors.
However the best solution is to build your own PSU which is very easy to do and doesn't require degree in electronics. We can help you with whats needed and will say if you can't wire this then you can't wire any of the machine it's that simple.
This way you get exactly what you need in terms of voltage and current in one setup and will work out cheaper than buying off the shelf units.

You will need a separate linear PSU for the Control etc and these are best bought off the shelf and cheap enough not bother building.

Hope this helps.