DISabling servo drive power on a DX/SX system

[wjr09]

Anyone ever find/figure out/come up with a method of DISabling power to the servos on a DX or SX system? Like many, I've toyed with the idea of handwheels on my V2XT, and installing them is a trivial affair, but having the DRO on the controller's screen would be handy to say the least. Hitting the E-Stop disables the DRO as well as the servos, so no love going that way. Would it be as easy as simply using a mechanical/electronic switch to interrupt the power to the servos? Has anyone ACTUALLY done this? Would love to hear ideas on how it could be done.

[dreammstr6]

I'm not sure about your particular machine but on my Bridgeport EZ-TRAK SX it uses a weld proof contactor to break one wire of each dc servo to disable the servos but it still reads out the position.

[wjr09]

Originally Posted by dreammstr6 I'm not sure about your particular machine but on my Bridgeport EZ-TRAK SX it uses a weld proof contactor to break one wire of each dc servo to disable the servos but it still reads out the position.

Excellent. Thank you for letting me know. Any chance you know WHICH wire it interrupts? I don't know what a weld proof contactor is, but I'll be looking it up, shortly. If you have the time, could you tell me what wire it interrupts, or any label the wire might have on it that I might be able to suss it out myself? Thank you.

EDIT - If you could take a picture of this contactor that might help, too. Maybe a part number... Not having too much luck Googling it...

[dreammstr6]

on my mill it uses a motion science power amplifier. on the x axis the wires going to the contactor is 36 and 41 which is the positive wire for the motor. and on y the wires are 40 and 22 which is positive for y. the weld proof contactor is a interesting design. it uses a external solenoid to ingage the contacts which are spring loaded riding on a plastic shaft.

[wjr09]

Thank you very much for checking that for me. I have the MSI drives in my V2, as well, so will be going to check it shortly. I've built a few things in my life, but I'm not overly knowledgeable about electrical components. EDIT - I'm wondering if this can be something as simple as just interrupting the continuity of this wire for each axis... like using a mushroom switch with multi stage connectors on the back. (one for each axis)

[dreammstr6]

yvw. the relay is 2 parts 31918156 relay pole ac m and 31918154 magnetic relay. i don't see why a heavy duty double pole single throw relay wouldn't work. all that happens on my mill is anytime you take the machine out of manual mode by opening a program or selecting jog or such is that the contactor pulls in closing the circuit between the 2 power amplifiers and the motors.

[wjr09]

Awesome news. Thank you again! I'm going out to the shop to do some poking around. I'll let you know how it goes... I'm thinking that a mushroom switch, some wiring, a few gib locks, a quill lock, and some handwheels might add some functionality to my old girl.

[dreammstr6]

as long as the mushroom switch can maintain it's position and handle the amps should do the job. a quick and dirty test i did on a EZ-Trak DX was to pull the positive wire on the output of each amp and tape them up. i was testing for the readout change on screen when we had a bad bmdc card. maybe you will be lucky and be able to do the same

[wjr09]

Originally Posted by dreammstr6 as long as the mushroom switch can maintain it's position and handle the amps should do the job. a quick and dirty test i did on a EZ-Trak DX was to pull the positive wire on the output of each amp and tape them up. i was testing for the readout change on screen when we had a bad bmdc card. maybe you will be lucky and be able to do the same

Just came back inside from the shop. What you propose is exactly what I am thinking to try, tomorrow. (little too exhausted to do it tonight) Checking my MSI drives and the machine's schematics, it looks like I have wire numbers 331/332 , 333/334 , 335/336 for the motor wires coming from each drive. I'll do a continuity and voltage check to determine which is positive and which is ground and then isolate the positive lead as you say yours does through the switch/contactor. I'm thinking I'd like a slightly more graceful approach than basically a light switch for this because as you point out - it has to handle the amperage... I'll have to ask of and rely on the helpfulness of others for that.

Other than that, looks very straight forward for gib locks. Quill lock will be another story. The boss it usually exists in does not exist, so I'll peek inside the mechanism's cover for some ideas in there.

Looking forward to doing this as I've always thought it was one of the three shortcomings of my V2.

Thank you for your help. I appreciate it.

Edit -

Maybe I could use a SPST rocker or toggle, utilizing the 24V circuit within the cabinet, to trigger a relay (or 3 relays) for this and label it accordingly. (Manual/CNC)

[dreammstr6]

yvw. i'll help anyway i can. i would suggest a 110 contactor and a 2 position switch to break the wires. one contactor if 3 pole could do all 3 axis's and would be a simple circuit

[wjr09]

Originally Posted by dreammstr6 yvw. i'll help anyway i can. i would suggest a 110 contactor and a 2 position switch to break the wires. one contactor if 3 pole could do all 3 axis's and would be a simple circuit

Just making sure I understand correctly -

Are you suggesting a 110VAC contactor because the servos peak at 90VDC? Also, what's yvw? I'll go look up a contactor to see what they cost. Thanks!

[dreammstr6]

yvw. short for your very welcome. and why i suggested a 110 contactor most machines i have worked on use 110 for the control power for the spindle contactors. so would be easy to borrow power from that circuit to energize your extra contactor for the axis interuption