Im buying G340s , which servos and encoders to get?

[Konstantin]

Hello all.
I finally ordered the G340s and I am still not sure about the choice of motors.
I would like to know what is your particular setup and if you like it or not and what would you like to leave or change in the setup.

I plan to use it with a medium Bridgeport mill 9"x42" XY table.

Also I think I will have to assemble my own PSU. Any suggestions on that regard are welcome.

Thank you.
Konstantin.

[Mariss Freimanis]

Don't buy a G340! Get a G320 instead and pick an encoder that meets your resolution requirements. The drive price difference is equal to what you will pay for an encoder.

Mariss

[Konstantin]

Thank you Mariss.
I have ordered the 340´s already and they shipped, the thing is that those are for a friend of mine and it was his decision to purchase those. Could you offer me some more information regarding the servos and encoders?

I am too are looking to get some of your drives later. Why do you insist on 320s against 340s

Thank you.
Konstantin.

[Mariss Freimanis]

Mostly to save you money. The G340 is for when you are stuck with a high resolution encoder and a wimpy max step pulse frequency from your CNC program. If you correctly size your encoder resolution beforehand then the G340 is unnecessary.

How do you size the encoder?

1) Multiply your motor's no-load RPM by 0.8, then divide by 60 to get your rated speed in revs per second.

2) Divide your CNC program's maximum step pulse frequency by the results from (1).

3) Finally, divide the results from (2) by 4. That will be the maximum encoder line count to get 80% of no-load speed from your motor using your CNC program.

The number might be funny-looking like 203.666 lines; pick the first lower standard encoder line count from what your encoder manufacturer offers (200 lines in this example).

For those that like tidy equations:

Line Count = (Fmax * Kv) / (53.33 * Vs)

Where Fmax = CNC maximum step pulse frequency, Kv = motor's velocity constant expressed as Volts per 1,000 RPM, Vs = Your power supply voltage.

Mariss

[yantra3d]

Thanks a ton for that very helpful bit of information there Marris!