Doosan Lynx 300 randomly jumping .010

I've been having an issue on my 2 axis lathe at work where a tool will randomly jump exactly .010. Important to note that it can jump in either X or Z, doesnt matter. When it does jump, the other axis stays dead on. It doesn't matter what kind of tool it is. It doesn't matter which tool holder it's in. It can jump positive or negative. I've had jobs set up where I've run off a bunch of good parts, then one tool jumps .01 in one axis, I'll adjust the tool, run off a bunch more good parts, then it jumps BACK to where it originally was.

At first I thought I was making a mistake somewhere or bumping something, but it's happened 5 or 6 times now in the past week and it's the same thing every time. I've run this specific machine for a year and a half now and have never had this problem once until the past week. It's always a single random tool moving .010 in a single axis while the other axis is fine. I can run off 20 parts that are perfectly fine then have it happen randomly. I work at a job shop I've been doing a lot of low count orders and this has happened on multiple different programs that are proven and have been run for years.

My boss thinks I'm crazy and that I'm making it all up. Does anyone have any clue what could be going on or am I crazy?

What control is it?
Once the control “jumps”, is each tool after that one off the .01? As in, does the issue follow through.
I was thinking an axis encoder has a problem, like it looses a 1/4 revolution which might equal .01 or something, But that would be for only one axis.

I would check the encoder as well as clean your limit switches for that axis. Are you sending the turret home at the end of the program or for tool changes?

Try running your parts without sending the turret home at all (once you've already homed it for the power-up), just move the turret far enough out to not crash on tool changes. That might give you a better idea of what is going on. If it is hard to convince your boss of the issue, it will be equally as hard to recreate the issue to a service tech. I own some Doosan lathes and have had some of the same issues as you speak but they were only on the Z-axis and weren't hopping around to the X-axis.

thinking out loud, but how many programs are in the control? this was a siemens 840c, but If you got to many programs
on the control weird thing started to happen. cleared the machine out except for a few programs and issues seemed
to clear up

Not sure about the drive system on a lynx- but if it’s timing belts the belts could be jumping a tooth? Might need to be re-tensioned or replaced.

Seeing as it can happen on either X or Z, you may want to check for loose wires in the controller cabinet, incoming power issues such as phasing, a bad ground, possible interference from other equipment. Also, make sure that all the screws and bolts are tight on servos, encoders, belts, etc.