New Machine Build- Boss 5 stepper drive question.

[Nick Hauth]

I started a thread in the Bridgeport/Hardinge forum. Maybe this is where I should have put it.
I want to run Mach on an old bridgeport with Boss 5. I am hoping to run the thing with as much of the original components until they fail. All axes jog under the Boss control,so I assume the drivers and stepper motors are currently working.
I would like to do away with my rotary phase converter and run everything except the spindle(VFD for that)with single phase 125 vac.
My only sticking point is the T2 transformer to the SX 1,2,and,3 transformer/rectifiers is three phase input.
I am not into electronics enough to understand what I am getting into.I do believe if I could drop the voltage to the correct level to each SX input,I would be home free.I believe the transformer said the output to be 60,70,or 80 volts and 15 amps.Voltage dependant on the output terminals used.
Is this as simple as doing a little calculation with Ohms Law? Or do I need a power source for each SX.
I am trying to do this with as little cash as possible. If this gets past the hobby/project phase,I don't mind spending on it. I just want to make some chips first and see if this is where I want to go.
Thanks for any help.
Nick

[keebler303]

I think you can separate the 3 saturable core reactors and run each off of single phase 220V. It is fairly easy to connect the machine to mach, I have mine done that way and it is really nice compared to the old control. I would recommend talking to Hillbilly here on cnczone. He sells a nice breakout board for connecting mach to a BOSS and has step by step instructions to walk you through which wire connects to which pin, etc. etc. Its pretty basic stuff and the result is great.

Good Luck
Matt

[Nick Hauth]

Yes,I actually bought a board from him. As nice a unit as anyone else is offering and less money.
You lost me at the saturable reactor.
I see three phase power coming in the mill and going two places. One is the spindle power. The other appears to be a step down transformer(T2).
T2 tag says it is a three phase transformer.The output(of each phase) is 50,60,or 70 volts(depending on which taps it is wired to) and 15va.
Two legs(L1 & L2)feed T1,a 125 vac 1kva transformer.This seems to feed everything else on the mill.
I just don't have the knowlege to know what I need to feed the SX 1,2,and 3 axis drives.This way I could get around the three phase altogether.
I suppose I could get a smaller motor and build a RFD to get me going.I was hoping for a simpler solution.

[keebler303]

Nick

Pardon my vagueness as it has been a long time since I have been in the back cabinet of my mill. There is a transformer back there. Under that are 3 saturable reactors (they look like transformers). They limit the current to the stepper motors. I have seen discussion in the bridgeport forum on people using single phase for the axis power supplies. I think they may have bypassed T2 and run the three saturable reactors in parallel off of single phase power. I really never paid much attention to it as I have 3 phase power available.

Have you done any searching in the bridgeport forum about converting to single phase? I think there is a lot of talk about it. It may prove helpful to troll around over there for a while.

Matt

[Nick Hauth]

I did put post over there. I think that the fact that this is a 30 year old machine, and that the ability to retrofit with reliable elctronics is hindering my quest for an answer.
I did a little searching for what a saturable core reactor is and it makes sense a little more whats going on. I was afraid this was a current control device.
I guess my next question is this:If I figure out the voltage out of T2 into the SX's,do I need to regulate the current into the SX's? Or will they(the SX's) only comsume what they need (current) to feed the axes at a given voltage?As the SX's purpose seems to be keeping the current controlled to the steppers.
I set out on this project to learn a few things and I think it's happening.
Thanks for the help.