[LUX93]

I've been having problems with a YCI Supermax with Fanuc O-M control. The machine was working fine last week, came in Monday and had a servo alarm for the x,y,z and couldn't get the machine to move. Somehow it lost it's parameters, so I punched in the 900's and communication settings and reloaded the parameters. It was overtraveling on X when Zero Returning so I powered off and did P+Cancel and it homed. I set my G54, and did not have any backlash problems when indicating. I ran looped program for about 20 minutes to check if it would go back to the proper zero. Y location is fine but X is off by about an inch, any ideas what would cause this?

[botha.y]

Going at low speed back and forth do you notice X going off position? If at low speed you are not losing your position, it might be 517 parameter servo loop gain, check that X has same value as Y and Z. If your machine was working properly last week your encoder should be fine, but if you are working semi-closed loop maybe swap the encoder between two motors to make the test just in case. You say you don't have a backlash problem, but having an inconstant backlash due to wear can also cause such an issue with several displacements, check that your backlash is constant at all positions. Check all those first.

[LUX93]

I'm not seeing any backlash when checked over several positions. It's only on X, it's not doing any rapid moves, I just have a program that drills 5 holes looping, the longer it runs the farther off it gets. I've checked the servo loop settings 512-513 they are at 1195 and 517 is 3000. I'm not a machine repair expert so I don't really know what these numbers mean. I'm just wondering if it's something more than a parameter, trying to get a machine guy out here but no luck so far.

[ifixcnc]

Call the US main office in Santa Fe Springs CA, they have free tech help. They are known as YCM these days.

[LUX93]

Just an update, emailed and called YCM and they were of no help. We did determine the problem, there is a drive belt that goes from the servo motor to the ball screw, apparently it is done this way so the machine has a smaller footprint. The pulleys are aluminum, so the oxide that forms eats up the belts, there was a pile of rubber shavings inside the enclosure. What sucks is, when I called YCM for a part, they could not tell me anything without the part number from the manual, which we don't have, when I asked if we could get a manual they said no. Luckily, it's available elsewhere, but YCM has sh!tty customer service. Hopefully we can get rid of this pile within the next year. Thanks for everyone's help.