Haas Y Axis Home Problem

Had this pop up and now and then this week on my Haas VF-0. When homing out the Y axis sometimes I would get an alarm "162 Y Servo over current". So I would simply press Home All Axis again, and it would be fine, well today it happened everytime, and I cannot get the machine to home out. Called Haas....of course late in the day and we tried several resolutions....switched the Y axis wire with the X axis wire under the luibe panel to rule out the switch...all is fine. Able to turn the ballscrew by hand....nothing stuck. Went into diagnostics and again ruled the switch to be fine. We ended the phone call with Haas having me remove the front way cover to see if something was stopping the Y axis from completing it's move home. Well I did that and everything looks perfectly normal, and in fact was rather clean under there. When the axis goes home, it depresses the switch and upon reversing is when it throws the alarm. By the time I tried calling Haas back with this info, it was 4:50pm and you know what that means.....voicemail....RATS....I need to work this weekend! Anybody ever have this problem, or have any ideas what it could be? I seem to recall having a problem like this when I first got the machine back in February and Haas had me change some parameter to actually move the home location a few thousands different and it went away, but I think that was for the X axis......they said it was too close to the limit, or something of that sort, can't for the life of me remember how it was done, and never thought of it while I was on the phone with them....anyone know what I'm talking about?

Later,
Russ

Russ,

I think you are referring to the "Grid Offset"..

It is parameter 126 for the Y axis...

I assume this is "brushed" machine..as you say VF0..

But first I'd shut the machine down..wait 10 minutes,(for the caps to bleed off) open the electric cab and remove and reseat all the Y axis driver cables..just the ones that plug in...The small reddish brown ones...no need to undo the ones screwed to the drive.. (that is if this is a brushed machine)..

I have seen this clear the alarm sometimes..as it is just weak/ dirty connection between the cable and board..

If you do change the grid offset parameter..make sure you right down your start value..and you might have to go either way..up in value or down..just go a small amount say 10..it will be a number like 33867 to start with..

FWIW, I used to get a servo alarm once in a while on my '96 VF3, at random intervals. It was always the Z axis, unless I had the 4th axis hooked up, in which case it became an alarm on the A axis. But when it finally became a non-resettable alarm, the LED's were out on the axis drives. The little power supply that fed the control circuits on the drive had died.

Russ,

Worth mentioning too..if you do change par 126..you would need to reset your Y axis work offsets too..as you are changing the y axis grid with this parameter..

Hi

I got a similar error once on our HAAS VF4

Please try this.

The Homing LS or (Proximity switch ) is fixed with 2 screws ,Loosen them ,then shift the switch away from you along the Y axis ...you can do this because they have provided some clearance on the holes..we are talking of something like 1 or 2 mm.)
CAUTION
IF IT DOES THE HOMING AFTER THAT , YOU WILL FIND THAT THE HOME POSITION IS SHIFTED BY ONE BALLSCREW PITCH. SO RESET ALL THE Y OFFSETS !!!

It is supposed to be done with a parameter ,But I didnt know how ,So I did it this way . Works fine after that.
MJM

Ok . I'm not absolutely certain which way I moved it finally,but I tried both ways .....

MJM

WMS....tried reseating all the cables....no change. Messed with Offsetting the grid, but didn't get anywhere with that either. To be honest though, I'm not really sure that was what I did several months ago, when I first got the machine and had this problem with the X axis...I seem to remember giving the service tech at Haas some position readings off of the screen and then he had me adjust something somewhere (not sure if it was a parameter or what)and then zero the machine and tell him the result of the new reading and he fine tuned it from there. In any event the current parameter reading for the X grid offset is 2300, the Y is zero, and the Z is 2100. I went all the way up to 2300 in the Y axis and still no change...would alarm. So I tried option number two from above......

sudtechcnc.....your suggestion worked! I loosened the two bracket screws on the proximity switch and was able to barely move it in the minus direction shortening the stroke, and PRESTO....machine goes to zero every time! Thanks a bunch! I am still going to call Haas on Monday and see what they say and ask about the settings I changed for the X axis to solve this about six months ago, and why we can't do the same for the Y axis. All right...time to go make some chips!! Thanks again sudtech!!

Go Red Sox!!
Russ

Russ,

Glad to hear you are running again..

The cable thing was along shot..but easy to do first..

I seem to remember giving the service tech at Haas some position readings off of the screen and then he had me adjust something somewhere (not sure if it was a parameter or what)and then zero the machine and tell him the result of the new reading and he fine tuned it from there.

Click to expand...

That would have been the "Distance To Go" value from the Position screen.. After you Zero-ed the axis you where working on..

My bet is that you might have needed to enter a minus value, (if you went from 0 to +2300 with no effect)..


But no matter, as you are making chips. And that is all that matters..

WMS........still not completely resolved. After lunch started machine up again, and got error when zeroeing axis', but at least when I did it a second time it zeroed no problem. I am still going to call Haas on Monday, or Tuesday (holiday Monday) and talk about those settings....it must be right on the edge. Don't understand why it would change the way it did, but maybe Haas can explain.

Later,
Russ

What are your consequences of Y not finding its home?

My X limit switch was screwed, until replaced i had to manually home the machine. Fortunately my software allowed me to pause a job and home the tool prior to a tool change or tool path.

Glad to hear it Russ.
you are welcome.

Looks like imminent switch failure .
better ask Haas to come with the spare switch ..

MJM

Started up the machine this morning....no problem....it ran great all morning. Shut it down for lunch, came back an hour later....won't run....can't zero the "Y". Talked with Haas and tried some more trouble shooting. Switched drives to rule out a bad drive.....same problem. Changed quite a few parameter settings to no avail. Was basically told the motor is most likely failing and I can get one from Haas for about $1500.00. I hate disagreeing with these guys, but I don't think it is the motor, so I pulled off the back way cover and fiddled around with the proximity switch again. I still think sudtech has it nailed....it's on its way out. When the machine goes to zero in the Y axis it contacts the limit switch and keeps going until you hear a soft thud, which is the table hitting the soft plastic stop that's installed on top of the ballscrew to prevent the housing under the table from smacking into the stop block with the bearings inside it(can't think of the technical terms for those things) which would then cause the 162 alarm Y servo overcurrent. So I backed the table away from the switch and pushed the switch in and out and could hardly hear any clicking noise at all. So thinking the switch is not getting depressed enough to make solid contact inside the unit, I wrapped a few layers of masking tape around the dog where the switch engages and whaddyaknow! It worked!! Not only did it work just once....it worked several times, even after shutting it down and starting it up again. The only thing I had to change was the parameter for the setting distance to zero, because at first I would get an alarm the distance was too short, but once I increased that...it works like a charm!! Just hope the masking tape doesn't wear off until the new switch gets here, which I will be ordering tomorrow. Should be an easy fix...two screws and plug it in. Happy days again!

Best Regards,
Russ

Its better not to run the machine with switches in that condition. (expecially the zero ref switch)

because thats which decides the position.

Now till its replaced . Everytime the machine is off and on again you have to take the trouble to ensure that the position (for the first job is correct).

pretty risky if you ask me.

MJM

sudtech....I hear ya....but for the 30 seconds it takes to check zero that first time in the morning to get 10 hours of production out of the machine is certainly worth it to me. Until the switch comes in it will stay on all day. It should only take a day for the switch to get here so I am hoping to be installing tomorrow.

Later,
Russ