DIY CNC 2

rodw wrote:

1. Doubling the motor voltage almost quadruples available torque
 

No Rod, not always, ONLY at higher RPM, and "higher RPM" for stepper motor hugely depends on size, inertia, inductance...

rodw wrote:

2. Any power supply for CNC can be overrated by about 40% so for 3 or 4 x 2 amp motors a 5 amp power supply is plenty
 

This is OK, but NOT a rule, and it is not overrated, it is underrated.
The only simple general "rule" would be :more voltage = less current, but that does not explain much
There is to much math involved there, together with the above mentioned inductance, etc

rodw wrote:

3, If a drive does not have a max temperature spec, be guided by the temperature the windings start to melt which is typically around 130 deg C but your motors are silent on that too. 80-100 deg C is fine
 

Or simply, if you put your hand on the motor and your skin does not remain attached to the motor, all is good, despite hurting absolutely unbearably to much.
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rodw wrote:

I can't see where you mentioned how many drives you are using. For CNC all motors are almost never running in unison and requiring full current is rarely needed.
 

Stepper motors will draw the maximum current when not turning at all, but most drives have a setting for it to lower current when idle, usually at half the set current.

rodw wrote:

3 motors at 2 amps = 6 amps. 6/1.4 = 4.3 amp power supply required.As I said a 7 amp power supply is probably cheaper.
 

Don't, this implies it is a rule,it is not.
Stick to underrating 40-50% for 24-48V power supplies, 50-70% for 90-130V, roughly. So the lower the voltage = less underrating.

Logthor wrote:

Is it really that significant? Using a 48V PSU vs a 24V psu. Unrelated, but I feel like you may be sponsored by meanwell.


 

No, I can second most of rodw's numbers. I nearly said the same thing earlier and didn't bother, as your original list looked like a good start.

You will get much better speed from your steppers if you power the drives with 48V

The greatest improvement will be that the fast moves between cuts will be faster.

NWE wrote:

You will get much better speed from your steppers if you power the drives with 48V

Yes, this is a fact, and the drives you chose should be fine on 48V.
Edit:
You can use a 24V power supply and make the machine work and use it daily, later on if you see you might benefit from higher speeds, you can add the 48V supply.

I think I have a pretty good idea of what I need, but I might switch the LRS to a 48V 10A supply just so that I have room to grow in the future if I want to.

Yes, this is a fact, and the drives you chose should be fine on 48V. 

The drives have a 50V max but if you don't think it'll cause an issue I'll go for it and see.

I would expect that adjustable PSU to work just fine for this application. Like I said, I would not bother adding a capacitor. But if you do, don't use the 35V capacitors I suggested earlier, for use on a 48V PSU.

The supply seems to have protections in place already for this so I'm probably not going to bother but thanks for the heads up