Geckos, power supply and servos

[snaggletto]

Hello,
I'm looking to put Gecko G320's/servos on an old Bridgeport CNC BOSS 5 I think (stepper motors are on it now). I need feedback on what I have so far;

1x toroidal transformer 120AC primary and 50V 24A secondary (1.2KVA). When rectified I should get (50 X 1.4)~70V 24A right? How many uF for the capacitor 10K+??

3x Electrocraft E643
Max Continuous Speed: 4800 RPM
Peak Torque: 720 oz-in 3.75 lb-in
Demag Current: 43 Amp
Motor Kt: 16.8 oz-in/ Amp
Motor Ke: 11.2 Volt /kRPM
Encoder: Renco 1024 ppr optical

The "seller" said the motors were 60V. Given motor Ke and max speed I calculate 11.2V X 4.8k rpm = 53.76V. Is 70V going to be too much voltage? Motor resistance and load will bring that 70V down right?

I should be getting more info on the motors. I'm planning on gearing them down maybe as much as 4 to 1. Any comments would be recommended.

By the way, I plan to use Mach2 for software and I will be running a 1.73Ghz AMD (XP2100 cpu).

[Al_The_Man]

You can usually take turns off of a toroidal transformer easily to bring the voltage down, There is a previous post where I outline this.
Al

[arvidb]

Yes, the 50 VAC will become about 70 VDC after rectification. But you cannot get more power after the rectifier than before, so the 24 A @50 VAC will go down to something like 17 A @ 70 VDC.

50 VAC * 1.4 = 70 VDC.
24 AAC / 1.4 = 17 ADC.

It doesn't really matter much what voltage you give the motors, as long as you have the current limit set correctly on the Geckos and the voltage is not too far off.

Arvid