CNC router steppers & power supply recommendations for GREX100 with 3 Gecko G203Vs

[Menatep]

Just got my hands on this machine recently and would like to finish it. The original builder of this machine recommends nema 34 906oz-in stepper motors for the X-Y axis and nema 23 425oz-in stepper motors for the Z-axis. Do you think that this would be enough considering that I am planning to cut wood, plastic, and soft non-ferrous metals? The complete gantry assembled with z-axis but without the router weights 90 pounds. Ball screws are 5/8” - 5tpi. Ideal cutting speed would be 100ipm, and jogging speed that I’d like would be 200ipm or so.

As far as electronics are concerned, I am planning to get Gecko G203V drives for all 3 axes and use Gecko G-REX G100 as the controller.

What kind of power supply would be ideal for powering the Gecko GREX G100, 3 G203V drives and 2 906oz-in and 1 425ox-in stepper motors from Keling Technology? When wired in bipolar/parallel connection the 906oz-in motors would use 2.1v and 6.1 A. 425oz-in motor would use 4.17v and 2.8 A

Many people on this site recommend that power supply voltage should be between 3-25 times its rated voltage and that a motor connected in bipolar/parallel connection would use 2/3 of its rated current. If that is the case, then I’m thinking that the ideal power supply will need 52.5v-80v and about 14.7 A ( (6.1 + 6.1 + 2.8A)*0.67*1.4 = 14.7 A ) for the 3 motors and 3 gecko 203v units… but I am not sure how the G100 will get power. It requires 12-24vdc power supply rated at 1.5A. Does G100 come with its own supply or do I need a separate power supply for it? Or is there a single power supply that can take care of everything?

I’m not really an expert in electronics, but what is the difference between single and dual shaft stepper motors? And what connection would be the best? I’m considering bipolar/parallel connection method and I wonder if it will be good for the cutting speeds I’m aiming for.

That’s about it…. Your replies would be greatly appreciated. If it helps, I will post more info about and some photos of this cnc router setup.

- Cutting dimensions: 40x28x7
- All 3 axes have 0.5" more travel than shown for limit switches
- Actual dimensions: 50x36x37 without motors or electronic components
- Gantry clearance without a table: 9.75"

- Linear Bearings
X: Fully supported THK 35 rails and bearings (1 bearing per rail)
Y: Fully supported Dual Vee bearings with hardened steel rails (cam adjusters on bottom rail)
Z: Fully supported IKO 20 rails and bearings (2 bearings per rail)

- Ball screws
X: Nook 5/8" - 5 tpi - with 2 Nook recirculating ball nuts so all play can be adjusted out
Y: Nook 5/8" - 5 tpi - with 2 Nook recirculating ball nuts so all play can be adjusted out
Z: Nook 5/8" - 5 tpi - with 1 Nook recirculating ball nut

ALL ball screws are supported by a bearing block on each end, the fixed end has two sealed dual angular ball ball bearings (these bearings take axial and radial loads), the other end has two sealed ball bearings.

Here are some pictures

Partly assembled machine...



Z-Axis...



Gantry attachment closeup...

[Oldmanandhistoy]

Hi,

If the stepper motors you have mentioned are wired bipolar then for bipolar parallel you will need 2 times the name plate rating.

For PSU current rating you need at least 2/3rds the total of all 3 motors.

Do you need stepper motors with such high holding torque ratings?

Single and dual shaft stepper motor, difference none other than dual shaft has the shaft coming out the back of the motor as well as the front.

I would stay close to 20 times Volts rating of the stepper to reduce heating.

John

[BobWarfield]

Gecko drives can run a max of 70V from the power supply. They are rated more, but that's what Mariss and others will tell you to give them as a max so they'll live through fluctuations. Make sure you set up the current limiting resistor properly for your motors and the Geckodrives will feed them the right voltages. You can ignore the nameplate from that standpoint except for their current limits.

The G100 itself has a wall wart for power. I'd stick with that.

You can read about my driver electronics to drive something similar to your requirements here:

http://www.cnccookbook.com/MTLatheCNCDrivers.htm

Best,

BW

[Menatep]

Some updates....

The Gecko GREX arrived today. It looks very nice.

The 906 oz/in motors were not available so i decided to go with 640oz/in motors. I hope it will not be too bad. There was an option of going with 1200oz/in motors instead, but i think this would have been overkill and i didn't want any problems associated with larger steppers.

Bob, I'm extremely impressed with your power supply build and i'm going to build the same thing.