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IndustryArena Forum > MetalWorking Machines > Okuma > Machine Not Cutting to Size
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  1. #1
    Join Date
    Oct 2018
    Posts
    14

    Machine Not Cutting to Size

    I was trying to diagnose why my part was not coming out correct. I've discovered that the position the machine is cutting in is not the same position as the code dictates. On the initial roughing operation the part is supposed to be cut to an OD of about 25mm but the measured part is coming out to about 27mm in diameter. I used a coax to determine that the X and Y position is correct and I think I can rule out the touch setter being the problem because the lengths are nearly identical to the exact same tool in our other Multus. Does anyone have any suggestions as to where to go from here? The machine is Multus B300-W. Thank you.

  2. #2
    Join Date
    Jun 2015
    Posts
    4131

    Re: Machine Not Cutting to Size

    hello again chronos, machine is not calibrated

    an easy fix : you have to edit the touch setter position; on osp 300, lb3000ex2, you find it in para\sensor position

    modify X+position with +2 or -2; do some trials

    pls be carefull, if you modify X+ position, check also X-position

    if you are going this way, maybe you should check also both Z positions

    if touch setter is down, and you press parameters buttons, it should open for you the "sensor position" inteface

    if you search on youtube "okuma touch setter calibration" you should find the movie " touch setter - how to calibrate"; i never watched it, because the guy recomands using tools, and i do it without tools

    so far i never calibrated multus, but only Y radial turrets :
    ... step 1) touch setter calibration
    ... step 2) encoders zero offset calibration

    I used a coax to determine that the X and Y position is correct
    if this verification is done corret, it means that step2) is ok, so all you need is step1)

    I think I can rule out the touch setter being the problem because the lengths are nearly identical to the exact same tool in our other Multus
    what lengths are identical ? are you reffering that putting same tool in both machines + measuring, should return similar offset values ? kindly
    Ladyhawke - My Delirium, https://www.youtube.com/watch?v=X_bFO1SNRZg

  3. #3
    Join Date
    Apr 2009
    Posts
    1262

    Re: Machine Not Cutting to Size

    Are you touching off in Z direction then rotating head 90 degrees for cutting? Or are you touching off in x and cutting without rotating the head?

    If 1 then head rotation center position is off.

    If 2 then calibrate touch setter position.

    Best regards,
    Experience is what you get just after you needed it.

  4. #4
    Join Date
    Oct 2018
    Posts
    14

    Re: Machine Not Cutting to Size

    I'm in the process of calibrating the touch setter. I spoke with an Okuma expert and he told me to use one of our tool holders of a known length/diameter to calibrate the touch setter. I did what he said to calibrate Z+, I touched of on the tool holder and adjusted the tool offset until the number on the calibration parameter screen read the exact length of the tool holder. I am not getting very far with the X+ calibration however. When I touch off X+ in base A the number on the parameter screen changes by a large amount and is not giving a number that makes sense.

  5. #5
    Join Date
    Jun 2015
    Posts
    4131

    Re: Machine Not Cutting to Size

    hi

    I spoke with an Okuma expert
    aha ... he was in a hurry ?

    he told me to use one of our tool holders of a known length/diameter to calibrate the touch setter
    so far so good : you need to know some absolute dimensions and offset zero reference planes ...i won't develop this right now

    I did what he said to calibrate Z+, I touched of on the tool holder and adjusted the tool offset until the number on the calibration parameter screen read the exact length of the tool holder
    when you calibrate the senzor, you should not edit the offset of the tool, but only the parameter value

    those number from the parameters should have really random values, but in the end, it will work

    pls, can you share the image from your parameter interface ?

    When I touch off X+ in base A the number on the parameter screen changes by a large amount and is not giving a number that makes sense
    unfortunately i don't have a multus, but if you could make a short movie with this procedure, maybe i can help ...



    to calibrate the senzor, you need to know the reference positions : pls look in attached image : for a radial turret, i know that offsetX=0 means that turret is at 90mm away from the lathe main axis; unfortunately, i don't know the reference position for a multus, so i made 4 drawings; my bet is on :
    ... drawing 3, thus M spindle line coaxial with S axis
    ... drawing 4, thus M spindle axis coaxial with S axis

    if i would know the reference position, maybe i can help

    On the initial roughing operation the part is supposed to be cut to an OD of about 25mm but the measured part is coming out to about 27mm in diameter
    just modify X+ value inside parameters with + or - 2, and see what happens / kindly
    Attached Thumbnails Attached Thumbnails Untitled.jpg  
    Ladyhawke - My Delirium, https://www.youtube.com/watch?v=X_bFO1SNRZg

  6. #6
    Join Date
    Jun 2015
    Posts
    4131

    Re: Machine Not Cutting to Size

    hello again i was looking over youtube for multus calibration, and i found this video

    it is not about a calibration procedure, but about showing that the machine is calibrated, by running some geometrical checks

    you may achieve same calibration ( same geometry ) values with different gridshifts: you may change touch setter position parameter, or edit axis base zero offset, and still have the machine calibrated; all those parameters may have random values, or specific values that point to real absolute dimensions

    overall, video it is pretty good; however :
    ... points 2-4, show that M spindle is coaxial with S spindle, and this determination calls for a centro; using the taster is not so exact, because :
    ...... there is palpator tir
    ...... even if tir is low, there is taster 360* fidelity
    ...... there is cnc axis backlash
    ...... it can not detect excentricities as well as a coax
    ... points 1&6 show that B axis articulation, togheter with X&Z, can move among a circle with it's center on part face; at least for 0* and 90*
    ... points 8&9, togheter with 4&5 show that B rotation is perpendincular on XZ plane

    i don't believe that the video covers all geometrical checks for your machine ( maybe you should search for such a list ); to have a clue, check this out : https://www.okuma.eu/technologies/in...tuning-system/

    if i would need to deal with a multus, i would go like this :
    ... senzor calibration
    ... Z paralel S
    ... X perpendicular S
    ... Y perpendicular XZ plane
    ... S axis is on B rotation plane
    ... M axis intersects B articulation
    ... encoders zero offset calibration

    kindly

    https://www.youtube.com/watch?v=eOzQeLata3o
    Ladyhawke - My Delirium, https://www.youtube.com/watch?v=X_bFO1SNRZg

  7. #7
    Chronos Guest

    Re: Machine Not Cutting to Size

    So I would change the Z value on the parameter page until the value on the offset page reads the known length of the tool?

    EDIT* I figured it out

  8. #8
    Join Date
    Jun 2015
    Posts
    4131

    Re: Machine Not Cutting to Size

    yes ... kind of

    that tool with known lenght shoud be a caliber, that is deliver with the machine, and has the 'length' engraved on it

    So I would change the Z value on the parameter page until the value on the offset page reads the known length of the tool?
    like this, you calibrate Z offset origin, more precisely you will put it in a position that is in accordance with that caliber

    however :
    ... you may shift that origin how you wish, thus it is not critical that "offset" is equal to "known lenght of the tool"; feel free to declare it how you like, where you like, maybe to sync it with an external tool presseter ?
    ... this procedure calibrates the tool, thus it is calibration towards Z+; think also about calibration towards Z-, thus program zero calibration

    you may calibrate Z+ and Z-, thus making zero offset and zero program to reflect an absolute position inside the machine; those positions you corelate with a CAM, and inside it you may simulate machine movement, check for colisions, etc

    i hope you find these usefull / kindly
    Ladyhawke - My Delirium, https://www.youtube.com/watch?v=X_bFO1SNRZg

  9. #9
    Join Date
    Jun 2015
    Posts
    4131

    Re: Machine Not Cutting to Size

    hei, one more thing : if the machine controller allows editing touch setter position and encoders origin, you may shift them how you like

    this function is not available on all cnc brands



    story time : somewhere, someone has buyed a tool preseter, so to enhance production, reduce auxialary times, etc; he find out that each machine had a different zero, so he could not use the preseter for all the machines



    is better to know how to edit all these zeros, and choose not to edit them, instead of needing to edit them but without knowing how / kindly
    Ladyhawke - My Delirium, https://www.youtube.com/watch?v=X_bFO1SNRZg

  10. #10
    Join Date
    Jun 2015
    Posts
    4131

    Re: Machine Not Cutting to Size

    On the initial roughing operation the part is supposed to be cut to an OD of about 25mm but the measured part is coming out to about 27mm in diameter
    hello again, that difference of 2 mm seems big, but it does not mean that something bad happened recently

    it is possible, that the machine was aligned a few times in the past

    however, is not enough to align a machine, also the touch setter needs to be re-calibrated

    otherwise, the touch-setter will show the difference between actual turret position and a past position ( it may be the position before machine shipment )

    each time the turret is re-aligned, new position is shifted from the previous; touch setter needs calibration, so to diminuate the position shift effect among offsets, etc / kindly
    Ladyhawke - My Delirium, https://www.youtube.com/watch?v=X_bFO1SNRZg

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