[rbickle]

Gentlemen,

I have an older model VF0E mill which I have cleaned up and been using for light work for several years.
Lately, the machine has started to get an "X axis servo error too large" error when homing the X axis. It does this at power up and after power up.
This doesn't happen all of the time, only occasionally, but it is becoming more frequent. Last time I fired it up, It wouldn't home the X axis at all.

I removed all of the way covers and cleaned everything up. I exposed the limit switch and am able to see the value change in the diagnostics screen when I press the switch.
I can look down the underside of the table and see that the ramp is centered on the switch properly.
I have reseated the connector for the X axis on the back of the machine as well as the X encoder.
I have opened up the coupler box and checked that the lead screw coupler bolts are tight.

I still have the error. It doesn't seem to matter if I zero the X axis with "Power UP / Restart" or "Zero RET" all or X axis only.
The machine will move the table left slowly then either home correctly or get the error with everything else the same.
I can jog X right and home again. Sometimes no problem, sometimes an error.

I think I'll just change the X axis home switch and see if that corrects it, but I though you gurus might have seen this before.

Thanks,
Rick

[Donkey Hotey]

You said older but, that isn't enough. We need to know if this is a brush or brushless machine to start (what year on the ID plate?).

Second bit of troubleshooting: most axis amplifiers and cables on these are the same. You can try swapping X and Y amps and see if the problem is with the axis or the amplifier. If it's still the X axis, you could do the same with the motors or cables, except...

Does the X axis ballscrew turn freely or could the bearings be seized? Common failure for older oil-pump fed equipment is the whole Vactra 2 way oil problem. The restrictor orifices plug, oil stops going to the bearing packs, they're under way covers so we don't notice until something stops working.

[rbickle]

Thanks for the reply, sorry, should have been more specific.

The machine was made in 08 of 2000. VF0E.

I can freely turn the X and Y lead screws. I currently have all of the way covers off.
I do suspect that the way oilers are not working properly, so I am replacing all of the metering valves and changing oil to mobil 1 as recommended by Haas. Also removed the old filter as it was clogged up.

I don't think that the problem is binding with the axis because it only happens when the X axis tries to home. When the table gets to the X home position, that's when the error sometimes happens.

I also have the following screen after startup, and I cannot find any information on the meaning of it.

Attachment 497868



Thanks again.
Rick

[Donkey Hotey]

Excellent and thorough reply. So we know it's a brushless machine and all the amplifiers are commonly available. That's good news.

The messages on the screen may be significant and may not. I had a bunch of problems with my VF-2 and also noticed a bunch of stuff written to that page. If you cycle through the Alarms button, it will take you through that screen and you can clear it if you like.

Me? I'd probably swap amplifiers first, just because it's easiest. Next, I'd swap the X and Y cables to see if it's related to one of those. Then maybe the motors. I read elsewhere a situation where a home sensor was slow to respond. It showed 1 or 0 after it parked but, it delayed in its action. You might watch that on the diagnostics screen as the machine is trying to find home. See if it trips immediately or is sluggish.

[machinehop5]

...locate the SIG Pot on the X amp board and give it about 1/8 of turn CW ...see if issue disappears. The X amp maybe borderline working and just out of tune because someone the than qualified personal has adjusted in the pass.

I'm not a Haas guy per say yet... but, doesn't Haas have a test program for Follow error adjustment? They should at leased have a readout some where in the settings.

DJ

[rbickle]

Greg,

That's exactly what I was thinking with the home switch. I can see that it changes state, but it may be too slow to actuate before the axis hits the stops.
I can try swapping the X and Y axes and see if the problem follows the axis or the hardware. It may error like that though since the switch offsets and such will be different.

Thanks,
Rick

[Donkey Hotey]

I was saying to remove and completely swap the components from axis to axis. I haven't had to do this yet but, I assume the X and Y axes have the same cables, same motors, same switches. I'd swap one component at a time until I got to the part that was acting up. Parameters and settings shouldn't affect that.

[rbickle]

I received the replacement home switch today and installed it. Problem solved.
The original switch did still trigger, but apparently too slowly for the machine. I tested both switches with a meter and noticed that the new one actuated much earlier in the compression that the old one.

Now I just have to put it back together. Just ordered a bunch of stainless Torx screws from McMaster to replace all those black oxide Allen head cap screws.
Half of those had balls of rust inside which makes then strip out easily. Had to grind a few of them off with a carbide rasp.

Thanks,
Rick

[Donkey Hotey]

It's always a good time to clean things out and do some housekeeping. On those stainless screws, do you know about galvanic corrosion? The stainless might corrode in the cast iron table. Coolant might protect it but, it's something to think about. Alloy steel screws are almost the same potential galvanically so they won't rot in the hole.

Since you have all of this apart, does your machine have the hydraulic counterbalance strut and tank? I'm toying with retrofitting my 2004 and wondering how much hassle it is to maintain.

[rbickle]

Yes. Last night I spent a couple of hours cleaning up the stainless way covers with a flapper wheel. Bright and shiny now.

I've never had a problem with corrosion on stainless hardware. The black oxide allen screws are just too prone to stripping. I'll keep that in mind though.
I'll also put some blue loctite on all of the screws which should help to insulate the threads.

This thing is 23 years old. If it runs good for me another 5 years, maybe I'll spring for a new one.

That counterbalance is on the Z axis? I don't think my machine has that. There are no external tanks or devices attached to the side. I have not taken the Z covers off yet though. Will plan to do that soon and change the metering valves too.

It's a shame that the previous owner didn't take better care of it. I couldn't believe the chips and dried up oil that was under the way covers.
I actually found a rat nest under the Y axis way cover toward the front. I bet that rat got a rude awakening when the thing powered up!
So far, I like the machine. Seems to be built well. I mainly bought it for the tool changer function.

[Donkey Hotey]

Yeah, you'd know if you had the counterbalance. It includes a big gas cylinder and gauge mounted to the side of the column. So 2000 didn't have them either? I'm not crazy about the Z axis being at 50% while at rest. I wanted to take some of that load off.

[gwood]

This error would normally be either a mechanical bind, servo tuning or failing servo, or servo motor causing a lag of the axis
from where it thinks it should be at a given feedrate, in this case at the homing speed.

[savagemachines]

I ran into this, My machine decided to identify as an arc welder. The xaxis power cable went bad in the center of the casting under the saddle. So I couldnt see it. I thought it was the servo amp and swapped in my b axis one. It was able to get it up and going then the cable completely failed and started its welding dance. I would look at your power cables to servo motors. I am trying to find out where to source the ampenhol connectors on the end. The power is 18-10 and the signal is 20-29. 12awg - 4c for power and the signal looks like 22awg - 10c. your millage may vary. the signal has a special molex on the connection in the back.