Milltronics Error 450 E-stop annoyance

[M_Controls]

I have been trying to diagnose a problem on a 5-year old Milltronics Partner ML-20 CNC lathe, and I was wondering if anybody else has seen a similar problem, and the solution. I have been troubleshooting CNC machines for three years. The annoyance is that the machine will just unexpectedly enter "Error 450: Emergency Stop." Sometimes it happens when the machine is completely idle. It is in a medium sized metalworking shop and no other machines have intermittant control problems, the electrical system is only 6 years old, so I do not suspect the power source; and I have repetedly measured the voltage. The problem occurs approximately once a week, but is entirely random. Once it happened about 6 times in a day, then waited a month. I have tried monitoring the 24VDC supply but it failed to malfunction when I was monitoring. I have talked to Milltronics repeatedly about this, and they keep saying try the same things over and over again - without results. One suggestion tried jumpering over the limit switches to rule out the opening of said switches, and rule out loose wiring there as well. Another suggestion was to jumper over the e-stop chain to rule out this part of the circuit as well. These jumpers did not help, the machine still acted the same. I have reseated all the computer boards & plugs, and checked for loose connections and bad solder joints all over. This has been ongoing for over 2 years now. The owner says he is about to throw it to the scrap bin. In the last 9 months other bizarre problems have been reported as well. One was that the spindle just quit turning in the middle of running a program, and the machine axes just came to a stop, with no error displayed on the screen. I seen this result, the screen just showed the tool path, and it was just dormant in the middle of the cut. I opened the electrical cabinet and looked at the spindle drive, it was in Stop mode and no faults. Does anyone have any ideas?

[Al_The_Man]

Is the E-stop string/relay hardwired to disable the servo's & Spindle etc? and does it have a contact on the e-stop relay to indicate to the controller that the e-stop has been activated, IOW is the e-stop input to the control for indication only?
If so you could leave the e-stop relay wiring the way it is for safety and jumper out the e-stop indication in to the controller.
If you have not already done the above, it could make sense that although you do not actually have an e-stop condition, the controller may think so by virtue of a defective conection/input into the controller.
Al.

[M_Controls]

It's one of the more complex e-stop wirings. I have already ruled out the e-stop and limit switch portion of the main e-stop chain by jumpering. They were two e-stop buttons - NC - in series, and in series with the NC limit switches. This loop exclusively controls a "control relay CR1C" in the "CNC card cage" - I/O board - so this is suspect as well. But this board is controlled by another I/O board, which is in turn connected to a PCI board in the PC via a small ribbon cable; so I cannot rule out either of these as well. What I haven't ruled out yet is shorting (to ground) of this loop. There is also another set of wires in parallel wiring on NO contacts of the e-stop buttons, which theoretically could also create the e-stop condition. But because the problem sometimes happens when the machine is idle, without external vibrations; and one e-stop button (& contacts) has been replaced; I do not suspect that this circuit is the culprit, but I can't rule it out - yet.

This is why I have asked if anybody else has seen this problem with Milltronics.

I must object to Milltronics lack of diagnostic data gathering - in the software programming - for this problem. I also dis Milltronics for mounting the spindle drive horizontally; for mounting it with less than 1" clearance on two sides for cooling, and less than 3" on a third side; and for the inaccessibility of the spindle motor wiring junction box - one MUST entirely remove the spindle motor to get to the spindle motor wiring junction box!

Milltronics used an overcurrent self-regulating type 24VDC power supply (linear), and did not install a fuse. So if an intermittent short occurs it could cause the problem described. My next plan is to change-out the power supply with a larger one, allowing me to insert a fast-acting fuse - of less current than the PS max, but about the same as the old one - to diagnose an intermittent short to ground.

[moldcore]

Yes, but it's made in America!

Our VM 24 (1999) has been rock solid except for some intermittent and unexplained electrical glitches. It has that same spindle drive but the cabinet for the VM24 is much bigger with plenty of clearance around it. It is sitting vertically. We had a service tech check ours about 2 years ago when a problem started appearing almost daily. It was his first Milltronics to service and had the same reaction, kept shaking his head. He found some bad connections some place that I don't recall now (up by motor I think), and the problem went away for awhile. It only took him a few minutes to find the problem. Now it only shows up about once every couple of months at most. Our problem was a spindle "oversomething" fault and the machine would have to be shut down for a few minute to clear the error. It was real annoying to say the least. The problem never showed in the middle of a program fortunately, only when the spindle was restarted after a tool change or first thing in the morning. Sorry that's not much help

[doug9251]

I am getting the same thing now with my '96 partner 6. w/ a 15 hp motor.
It just e-stops (error 450) when it feels like it. Sometimes changing tools, while cutting, and jsut sitting there.

It is a ghost in the machine. I was told by Bob in parts, that it was probably (in my case) the cable package the goes from the spindle drive to the top of the motor. 6 or 8 little red and black wires that break going into the phoenix connector.
Bob told me to dike off, strip and tin them.

But, the machine started cooperating agiain, and I'm under the gun to get parts out....so hit the blinkey green button.

Doug.

[Mudflap]

I had a similar problem on my 2001 ML-20. It would just fail to run, or stop and show an error. It's been long enough that I don't remember the error, it may have been E-stop. We couldn't find the problem, we were ready to send the control in to Milltronics for them to repair it to find the problem. It turned out to be a failing microswitch on the chuck safety guard.

[M_Controls]

Originally Posted by Mudflap I had a similar problem on my 2001 ML-20. It would just fail to run, or stop and show an error. It's been long enough that I don't remember the error, it may have been E-stop. We couldn't find the problem, we were ready to send the control in to Milltronics for them to repair it to find the problem. It turned out to be a failing microswitch on the chuck safety guard.

Mudflap: I believe the chuck guard saftey switch does not cause an error message to come up on the screen. I also had to replace the chuck guard safety switch on my client's ML-20 (recently), and it did not cause an error message. BTW, I believe that the chuck guard safety switch broke because of the model selected and the method of mounting (dual-mounted, through 2 thru-holes in the switch and flange or panel-mount on the plunger actuator). What's more, I found that it had been attempted to be sealed with blue silicone, and so perhaps was broken previously, I suspect perhaps at the factory. The mounting creates stress from heating & cooling, since different substances expand and contract different amounts when the temperature changes enough. I recommend that the two side mount bolts be left somewhat loose allow some slippage.

I also drilled a 1/8" hole in the cover to allow drainage of seeping coolant - since this switch works on low voltage the coolant does not hurt it except that over a long period of time it may corrode the internal switch metals - but this will happen anyways as this is not a sealed switch by the switch manufacturer's design! It allows coolant in by way of the actuator plunger! (And around the switch housing.)

[M_Controls]

This is in regards to the original post that started this thread:
First, let me say a quick word regarding my last post, the machine had two separate problems. One was the chuck guard safety switch, but that did not cause the "Error 450: Emergency Stop," so that was a separate isssue.

I replaced the 24VDC power supply with a larger one (2.4A -> 3.6A, linear), and put a 2.5A fuse in the output to indicate whether or not there was a short somewhere. The customer has not had a problem with it since - 3 weeks. It is possible that the power supply was failing for just a split-second occasionally (I could not catch this happening with my recording meter), or it was undersized and just barely supplying enough juice - it has an automatic overload protection, so it would just shut-down for seconds occasionally if this was the case. High enclosure temperature also derates the PS output rating and thus can cause this PS shut-down, but we could not link this problem to summer heat. I may never know which problem was occurring, but I now know how to fix it - providing it is actually fixed permanently. Only more time will tell.

[Farmers Machine]

Most of my ghosts when my ML 20 and RH30 were new in 2001 were from to high voltage 254 to 263 on a rural coop line. bought a transformer and took care of them. There is a 220 volt sticker on the box cover and that is not 240 volts it really means 220. other problems with machine " Locking up" were caused by summer heat. Opend the cabinet and ran with fans blowing on USA control box and servo amps.

[M_Controls]

Replacing the 24VDC power supply with a larger output model seems to have fixed the "E-stop" error annoyance. I will never know if it was defective or just sized too conservative. The linear type power supplies are derated according to ambient temperature, and it was probably getting to 40 degrees centigrade (about 105 F) in the cabinet. Those power supplies have automatic thermal shutdown, which would automatically re-start (after the "E-stop" condition occurred) when it cooled sufficiently, that could occur very quickly in the case of a marginal overload. So I suspect that the PS was operating as designed by the PS manufacturer, but I would never install a used power supply in another customer's machine to find out. This machine is in Maine, USA; we do not have nearly the hottest summer temperatures in the country. And, my closing comment: I was not able to associate the failures with high daytime temperatures. I wish good luck to all of you.

[pixburghenat]

Originally Posted by Mudflap I had a similar problem on my 2001 ML-20. It would just fail to run, or stop and show an error. It's been long enough that I don't remember the error, it may have been E-stop. We couldn't find the problem, we were ready to send the control in to Milltronics for them to repair it to find the problem. It turned out to be a failing microswitch on the chuck safety guard.

I had the same thing happen on an ML15 and I can't remember if there was an E stop error.

But, I had the spindle lube pump act up and it was giving me an E Stop.

enat

[M_Controls]

2007 update: The new 24V power supply fixed the problem, but there has been other occasional problems with the same machine. I also had to replace the main lube pump due to electrical corrosion caused by coolant getting in to the pump electronic controls. The next two replacements quickly failed, the pumps would go crazy and just keep pumping too much oil at irregular and reduced intervals, regardless of the pot setting. So I had to replace the uinit with a Bijur mechanical timer unit (model TMD-1; 26350-1) that is better sealed against outside contamination.