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Thread: lathes

  1. #13
    *Registered User*
    Join Date
    Mar 2006
    United States


    The mudracer may be right about the B-Axis motor to leadscrew slipping. This is the likeliest reason. However, I had a SKT21LMS that I worked on that I never got fixed. It would home out but could be off one revolution either way. It never would change while the machine was on but the next day could revert to the previous location, always by one revolution. Fanuc and Kia could never fix it.

  2. #14

    Default B+ axis Over Travel fault

    I spent a few hours yesterday homing the machine and testing all the limits over and over again. I did notice that after the machine homed the machine position would register .0191 for B axis not Zero. I called the dealer I got the machine from last year and they suggested I Shut the machine off and power it up holding the "P" ( which is also the "O" ) and "Cancel" buttons down while the computer boots. It worked. I homed the machine and all axis Zero'ed correctly.
    I did'nt stop there though. I checked the limits over again and would sometimes get that .0191 error again. It I believe is the amount of B+ axis over travel which the parameter is set to 500 ( 1/2 a millimeter). So I think maybe that the software limit is too close to the home prox sensor. I'm going try mudracers advice and increase that limit to 1000 like it is set for the x and y axis ( and watch it closely). Most likely the the coupling slipped a little on the Ball screw, ( the screws on it weren't very tight).
    I had a similar problem to Lyfordln with a Bridgeport 760Vmc z axis homing some times off by a revolution , and it was that the homing proximity switch was too close to the timing mark on the encoder. All it took was moving the trip dog a little so it would hit the switch aprox 180 degrees from the timing mark on the encoder.

    Thanks for the replies

    Last edited by tapburrbit; 04-12-2008 at 11:57 AM. Reason: typo's

  3. #15


    Be carefull when using the cancel+P while booting. If you slip up and hold delete+p youll wipe out the parameters and cancel+del+p wipes out the entire controll.

    as for the stored stroke error. if you cant get it fixed add a g23 to your program start line and this will ignore any saftey zones.

  4. #16


    We recently also got our SKT21 LMS with a 0I TC controller. We faced the same problem with ridgid tapping. Then we got the advise by KIA to activate rigid tapping with M126 and after that it worked fine.

  5. #17

    Lightbulb Ridgid Tap with main spindle and live tool !

    Quote Originally Posted by g-coder05 View Post
    I used to run an SKT21 LMS, the machine was ok i guess. i never could get it to rigid tap right (live spindle or main) i wound up havind to use a floater to get a decent thread. there tech support is a little lacking unless you speak Korean. Cumsa hamita....
    Hey I'm using these G-code sequences for rigid tapping on my SKT 21 LM (Fanuc Oi-Tc)

    G28 U0. W0.
    G40 G80
    T0606 (TAP 3/8-16)
    G0 X0. Z.5
    G97 S500 M3 (speed)
    G84 X0. Z-.5 R0. F.0625
    (X-> position, Z->depth, R->retract in front of the workpiece, F->feed in in./rev. <pitch of thread>)
    G28 U0. W0.

    G28 U0. W0.
    T0606(TAP 3/8-16 FACE LIVE TOOL)
    G0 X0. Z.5 C0.
    M90 (use the high pressure c-axis brake if you don't want any torque limit alarm)
    P4 P1000 (use a pause to let the ''M90'' going all the way before tapping starts)
    G97 S500 M13
    G84 X0. Z-.875 C0. P500 R0. F31.25
    (X->position, Z->depth, C->angle of main spindle, P->pause of .5 second at the bottom of hole, R->retract in front of the workpiece, F-> feed in in./min <pitch of thread multiplied by speed>)
    G28 U0. W0.

    If any questions about, this send me a private message

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