Wiring Diagram Proof

[stein]

Yes, I know, yet ANOTHER wiring diagram posted here. This is in no way a schematic, but I feel like I'm missing a major passive component or two. Also, the system I've designed is a bit more complicated because of the encoders and their interface for the steppers. Motors are 1410 oz/in and use 6.3 amps, not sure if the current set resistor is even necessary. Also not so sure about the power supply design, seems a bit too simple. The transformer I'm using is:

http://cgi.ebay.com/12V-x4-at-1-2KVA...QQcmdZViewItem

Thanks in advance.
The schematic can be found HERE

I apologize for the quality of the drafting, I'm a far cry from an electrical engineer.

[CJL5585]

First of all, I would recommend wiring the transformer for an output of 24 Volts AC. After rectification and filtering the voltage will be approx. 34 Volts DC.

Wiring the unit at a higher voltage will not give you hardly any increase in overall speed but will cause A GREAT AMOUNT OF heat generated in the stepper motors themselves. Also, a stepper motor acts as a generator when excitation is decreased and the motor is slowing down in speed. At the high voltage, you will most likely exceed the voltage rating on the drives and will definately exceed the voltage rating on the filter capacitor.

One should use the lowest voltage possible to attain proper operation of the drives and the steppers. At 34 Volts DC, everything should be acceptable.

The Gecko's should be heatsinked and fan cooled. Each Gecko Should be fused with a 5 Amp fast blow fuse after the filter capacitor.

I would not recommend powering the computer and the power supplies on at the same time. The computer should be powered on, the program loaded then, turn on the CNC power. This relates to safety and the possible movement of the axis during startup under certain conditions.

The above is based on experience.

Hope this helps, and good luck.

Jerry

[CJL5585]

When the operating system is loading, it checks the parallel printer port for certain signals which relate to a printer being attached to the computer. Therefore, some signaling takes place at the output of the printer port.

This information transfer would be seen by the drives as control signals and could cause all sorts of problems and movements and could be very dangerous to the operator if he were close to the machine.

Just thought I would elaborate some on the dangers during system boot if the CNC controls were powered on.

Jerry

[ger21]

Jerry, thw Campbell breakout board has a charge pump circuit, which needs a signal from Mach2/3 before it will do anything. This is to prevent the problems you speak of.

One thing I noticed is your E-Stop. Looks like a software only E-Stop. Have you thought about having the E-Stop kill power to the power supply as well. If not, it's not much different than a pause. A real E-Stop works in all emergencies. Not just when the software has control.

[CJL5585]

Originally Posted by ger21 Jerry, thw Campbell breakout board has a charge pump circuit, which needs a signal from Mach2/3 before it will do anything. This is to prevent the problems you speak of.

Guess I did see the Campbell breakout board since you mentioned it, but it did not register in my brain at the time. Guess that has to do with too much stress and my age.

Jerry

[stein]

Well, first off, if the software crashes, no pulses can be sent, correct? Either way, if such an event was to occur as to require a hardware e-stop, the mast power switch can be hit as well. Having them in one button would be nice, I guess I could through another relay in there. Just figured it wasn't necessary. Is there an easier way?

Jerry, in response to both the computer and electrontics firing up at the same time, that is not the case. The relays which switch on the electronics and the electronics cooling case draw the 12v power from the computer supply, which, must be turned on first.

All other comments are taken to heart. I've reduced the voltage to 54, but less than that kills my torque. I think I can use the same recifier and cap.

Thanks again,
Ben

[ViperTX]

Well if the software crashes....no telling what pulses are sent.....and use the Gecko's recommendation for current set (limit) resistor.