Strange issue with lathe today. <resolved>

[dmbgo]

I might be doing something strange, but my lathe keeps losing it position, resulting in a broken tool tip and damage to the job while boring.
Here's what I am doing:
1/ measure the hole that I am starting with ( in this case 15.76mm)
2/ Move the X: axis with the mpg until it is just inside the hole.
3/ Set the X: position to the measured diameter of the hole. (15.76mm) and the z: axis to zero, just outside the hole.
4/ create a job in intercon to bore 1mm out of the hole, taking the hole to 16.76mm
5/ Run the job, which completes successfully
6/ measure the bored hole again and set the axis to match the real diameter, say 16.5mm
7/ modify the existing job to now bore the hole to 17.0mm
8/ start the modified job and have the tool hit the workpiece at with the X: axis saying 16.06mm and the z: axis saying it's at -1.030mm. The X: axis is really at about 27.0mm from the centre line of the lathe, not 16.06 as the DRO is reporting.

I have done this twice now, and have checked obvious things like loose pulleys on the axis etc. I am perplexed.

When I said "losing it's position", I might have been more accurate by saying that it is moving to the wrong position, which causes the crash. I must be doing something to cause this, I have had no issues turning, and I seldom need to bore things.

As a background, the machine, is a cheap Chinese lathe, fitted with ballscrews and Adtech AC Servos by me.

[kb58]

How long had it been working correctly, and what's the last change made (if any) before it started moving to the wrong position? Were any cables changed in any way? Was any software updated or modified? First thing I'd do with it powered up and at a static position, is to wiggle every connector in the system, watching for an "emotional outburst."

[dmbgo]

It has been working for several years, but I did replace a couple of driver ICs in the early days, due to an impetuous bad decision on my part.
That being said, I went and did something else, then altered my program to start 20mm in front of the job, so that I had time to hit stop before any catastrophic damage occured. After doing that I ran the same job again. The lathe behaved flawlessly, and has done since then.
The issue seems to have gone. Perhaps it heard me typing as I was asking for help and knew the game was up.

[dmbgo]

For interests sake, I have now worked out the cause of my issue.
The issue occured when I measured the size of the hole after running an initial job. I would then change the X: position to alter the X: position. What I didn't do was realise that I was using a differen boring bar to the one that intercon thought I was using, so the offsets in the tool table were causing my issue. If I had bothered to put this boring bar into my tool table the issue wouldn't have happened.

[suntravel]

Fine that you figured it out. I have labels with the tool# on my quick change toolholders, to avoid putting in wrong tools.

Uwe