[Sparo2]

Hi everyone.

I'm new to the whole CNC world. In the past I would make everything by hand with no computer assisted machines. A buddy of mine who has been a CNC operator for 10 years has recently introduced me into the whole CNC world and I decided to buy one. Again I am new to all this so please go easy on me.

The machine is a 85 Okuma & Howa Millac 4va. Before I purchased the machine the seller ran it for me to make sure that everything worked. The only thing that didn't work was the tool changer. For some reason it doesn't pick up on any of the commands, but we'll leave that for another day. I just finished wiring my garage and decided to power everything up.

I'm going to start off by telling you guys how I have everything wired. From my main service panel I have 2 gauge cable feeding 220 V to my garage and into a 70amp breaker. From there the 220 V goes into a 3 phase rotary converter to generate my third phase. From the converter I have my three phases coming out and into a 60 amp breaker. From that breaker I have 6 gauge cable running to my CNC for power. Just so you know my rotary converter a a 25hp unit.

Now here's my problem...
I turn on the machine and push the machine ready button. I then send all the axis to home (x, y & z). A few minutes later the machine ready light turns off and my hydraulics turn off. I go to the service panel on the machine and noticed there is a relay that is pushed out (MS1). I push the relay back in, go over to the control panel, push in the machine ready button and the machine ready works again. Then a few minutes later the machine ready light goes out again and my hydraulic stop working again.

Again I am very new to this so I apologize if I sound like an idiot. Any help would be greatly appreciated.

[Greenbuggy]

1) where you located
2) Do you have a set of wiring and or ladder diagrams for this machine
3) what control is on the machine

I have a 1984 Okuma & Howa MC-4VA as well and I'm slowly learning my way thru it. If you have a Fanuc 6M and a set of wiring or ladder diagrams I would be more than happy to throw some money your way to get a copy or scan made of them.

There are distinctly different wire numbers between the Fanuc 6M controlled machines and the 11M controlled machines, so if you do not have a 6M disregard what I'm about to write below:

The machine ready system runs an e-stop loop thru all of the axis OT switches. These switches are LS1-LS6 that correspond with X+, X-, Y+, Y-, Z+, Z- travel limit. Wire numbers start around 200 and make a loop thru the "machine ready" pushbutton and E-stop operator right below it. When you hold in the "machine ready" button it supplies power to a cube relay that is supposed to latch on the upper left side of the cabinet with the servo and spindle drives and other non-computer electronics. If the machine has overtraveled you can hold in the "machine ready" pushbutton while using the jog buttons in jog mode or MPG in handle mode to move that particular axis away from the OT switch.

What sounds like is happening on yours is that the contacts in one of those Omron switches is going bad, when it heats up a little the resistance is such that it no longer holds the relay latched and the relay releases. If I were you I'd be pulling all of the covers off of the Omron DM switches on the right side of the spindle, on the base of the machine on the left side under the saddle and on the saddle in the middle under the sheetmetal, and checking resistance of the NC contacts with wire numbers around 200. If you find any that are over say 3-4 ohms I'd strongly recommend replacing them, ditto for any that appear to be badly corroded or seals compromised (wet inside)

Could be where wires interconnect on the terminal strips on the bottom left of the cabinet. No harm to be had spending some time with a screwdriver to tighten every one, especially on a 30 year old machine.

Could also be the relay contacts going bad - you could try replacing the relay as well. But I'd be starting with the limit switches as they are most likely to be damaged by chips/coolant and abuse in transit.

As for the tool changer I'm working thru some issues with mine as well, I have both the operations manuals in PDF for the 11M MC-4VA and 6M MC-4VA so if you PM me your email addy I can send you a copy that shows the error display on the tool changer. If the tool changer isn't responding to commands its likely that its lighting up an error and will not move until the error is resolved. Resetting the tool changer (if its a sequence doctor) is done by e-stopping and restarting the machine ready system, but some errors will not automatically clear until the condition causing them is resolved (in my case needed new batteries for toolchanger PLC and more way oil in the lube pump reservoir)

Another late to game thought: are your taps set correctly for voltage on the transformers, both the ones inside and outside of the machine? If you had lower than ideal voltage going thru the E-stop circuit it would exacerbate any problems you might already be having with corrosion or loose connections.