[megaisomot]

Currently I'm operating a Kitamura H-800 HMC with a Fanuc 15M control. The problem popped up just yesterday when I tried to jog the table toward negative X direction. The jog speed was extremely low (7.8 in/min). There was no problem jogging the table back toward positive X direction. The other 3 axis appeared to be normal as well when using the jog function. Jogging speed under #1423 in the control was set to 1000 mm/sec.

I tried MDI mode to rapid traverse the table toward ONLY the negative X direction and experienced the same problem as in jogging mode. The same thing can be said when I attempted to run an existing program in Auto mode. Rapid traverse speed with toolpaths relating to the negative X direction was affected.

I appreciate anyone out there that can render an opinion as to what's wrong with the machine.

Thx

[gridley51]

I would hazard a guess that the 1000mm/second that you are trying to set is outwith the allowable setting range and the control is defaulting.
1000mm/sec is 60 metres a minute which seems a bit quick for an old machine.

[megaisomot]

Actually it's a typo. The setting should be 1000 mm/minute. However, it's strange that the slow rapid traverse speed occurred only in one direction of the X axis. No problem with G1 feed for all four axis in any direction.

[springlakecnc]

Check this out:

I solved a simular problem once. The gibb was lose, so going one direction, was no problem, BUT, going the other direction, the gibb sucked in to the point of, slowing AND sometimes stopping the axis!

Remember, when troubleshooting, deturmine if the problem is mechanical or a control problem first. Try turning off the cnc and reach up under and turn the ball screw by hand, that may tell you something.

Good Luck.

[megaisomot]

Thanks springlakecnc. That's a good thought. I took your advice, opened up the machine and inspected the gibbs for traces of looseness. The gibbs seemed to be well secured at both ends of the table. This ruled out the mechanical problem portion.

While I used MDI to return the table to home position, I noticed that as the table approached close to home it decelerated at a speed of 7.8 in/min. This speed is similar to the speed that I read off of the display while jogging the table in the troubled -X direction. The deceleration mode was activated when one of the button on the multiple plunger limit switch box hit one of the rams on the end plate near home (there is another plate at the other end of the machine's limit on the X axis. Same thing for Y and Z). The next step for me was to move the table away from the end plates located at each end of the machine limits to release all of the buttons on the X, Y and Z limit switch boxes back to OFF state. I activated the PMC mode and search the Ladder Diagram area that related to deceleration mode to check if anyone of them was on. Only the deceleration mode at -X was still on while others showed OFF state. It turned out that one of the button on the X axis multiple plunger limit switch box was jammed with sticky coolant and fine chips. I took apart the box and reset the switch, the problem was solved. However, the X axis limit switch box is in a very bad condition. All the seals surrounded the buttons are worn & could not keep out coolant or impurities. It needs to be replaced.

Anyway, I really appreciate the advice given by the members in here.

Thx,
Kev.