[samsagaz]

Hey guys, i want to know wich will be the fastest stepper (nema 23 or 17) to use into an small (very small) drilling cnc
Weight to move will be very low (think abt 1kg of table (12mm MDF, 50x25cm) + 2 x SBR16 rails (that can be attached to the table) that will weight less than 2.5kg so total will be close to 3.5Kg.

I will use an fixed gantry to get an solid Y and Z axis and lighter X.


About Drivers was thinking about am882 that support 70V!

Well thanks in advance

[KOC62]

Your question is too general, as one can't say which is faster. There are other parameters you will need to add.
For example the lower inductance of the two stepper will be faster for a given power supply.

On a test bench I have driven my Nema 23 motor (6.8mH) to 4K RPM under no load with a 48VDC power supply.
At this speed it may not be of any practical use as the torque would be.just enough to turn the motor shaft.

[samsagaz]

Your question is too general, as one can't say which is faster. There are other parameters you will need to add.
For example the lower inductance of the two stepper will be faster for a given power supply.

On a test bench I have driven my Nema 23 motor (6.8mH) to 4K RPM under no load with a 48VDC power supply.
At this speed it may not be of any practical use as the torque would be.just enough to turn the motor shaft.

i know that its too general, but at least you say that i need to search the lowest inductance possible!

so need to search for Lowest Inductance and highest torque, right?

After search found this

option 1 4.2A 1.2mH and 150 N.cm Holding Torque
option 2 4.2A 1.8mH and 180 N.cm Holding Torque
option 3 4.2A 3.0mH and 250 N.cm Holding Torque

if i will need to move low weight option 1 will be the best then.

[KOC62]

Yes.
It takes time for current to build to full value. It's called time constant. The more inductance the higher the time constant. This in turn limits the upper RPM.
You can also check stepper specs to see the torque vs rpm.
Another factor that can help RPM is to raise the power supply voltage so it takes less time for the current to reach its full value. Often the stepper driver has a voltage limit which is lower than what the motor could take.

If you know the maximum torque the motor needs to move your table then it can help to decide what motor size is good enough. Right now we are dealing more with a qualitative view rather than a quantitative view. (i.e no torque numbers or RPM numbers as they are unknown right now).

[plcamp]

The motor may be able to handle the increased voltage just remember to use a driver board suitable for the target voltage. Another consideration is that actual machining will be at less than the full speed capability of the machine. Cutting speed, surface finish and tooling will how fast you should move the machine.