Techinical Diference between GO and G1


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    Default Techinical Diference between GO and G1

    I hope I am posting in the right area.

    I am writing a new post with some new cutting strategies for cutting melamine.
    One thing that has always bothered me is the transition between interpolation moves such as G1 and G0 moves.
    Every controller I work with makes you come to a full stop during this transition.
    My goal is to eliminate that. I have several reasons for doing that. I would rather not get into a discussion about why.

    I know on some stepper machines they reduce the micro steps to move faster during G0 moves.
    Does this apply to servos as well?
    I understand from a practical standpoint that G1 speeds need to be set in code and G0 is usually a controller variable.

    It there anything stopping me from setting the max cutting speed to that of the G0 speed and being careful when cutting?

    FYI: My new post will be written for the OSAI Open-XS controller.

    Thanks,
    Bob

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    Community Moderator Jim Dawson's Avatar
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    Default Re: Techinical Diference between GO and G1

    A G0 move is a rapid move to reposition the tool bit (or table) for the next cutting sequence. On many controllers, it is not a coordinated move. In other words the X and Y may not arrive at the commanded positions at the same time. Normally the Z axis would be retracted to a safe location before executing the X/Y G0 move at the set rapid speed.

    A G1 move is a coordinated linear move of one or more axis, and is normally done at cutting speeds. A G1 move could be accomplished at any speed you set in the G-code, up to the maximum speed the machine is capable of.

    No, setting different step resolution would not apply to servos.



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    Default Re: Techinical Diference between GO and G1

    Hi Jim,

    I have a clear understanding of the difference between a G1 and G0 move and their practical use.
    What I want to do is eliminate the stop at the transition between the two.
    I am wondering if I can get around that by setting the MAX interpolation speed to be the same as G0 speed in order get around that? Of course I would have to be careful only to use that speed when out of the material.
    The last time I tried this was on a Shop Bot with steppers and it could not be done because G1 moves used smaller micro steps and would error out if I tried to move a G0 speeds when out of the material.
    I dont know whats going on in the background with Servo motors and why exatly the machine must come to a full stop when changing from G1 to G0 and visa versa.
    I am trying to work arround it.



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    Community Moderator Jim Dawson's Avatar
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    Default Re: Techinical Diference between GO and G1

    There is no reason that you couldn't make a G1 move at the maximum speed that the machine is capable of. It is possible that they are changing the acceleration parameters when transitioning from a rapid to a G1 move. That might require that the axis is not moving during the accel parameter change, I know this is true on some controllers. Normally the acceleration (and decel) is set a bit lower on a rapid move to get a longer ramp time and smooth out the machine a bit.



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    Default Re: Techinical Diference between GO and G1

    That is very interesting.
    Ac and Dec would almost be moot becase it would not be starting from a stand still or slowing to a stop.
    I plan on cutting at 25 to 30 meters/min and transition to 80 m/m for rapids. Should be pretty high up on the curve already.
    I am pretty sure I can change the Ac and Dec settings with code on the fly if I needed to.
    Not sure that it would require a full stop to take effect.
    My plan is to do a smooth lead in and a smooth "lead out" thus eliminating 2 full stops per part.
    Theoreticlly, this should cut down on machining time, machine wear and bit wear.



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    Community Moderator Jim Dawson's Avatar
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    Default Re: Techinical Diference between GO and G1

    I know on the controllers (Galil Motion Control) that I use, I can change the accel on the fly, but decel can only be changed when motion is stopped. It errors out if I try to change the decel parameter when in motion.

    Having said that, leaving the accel/decel parameters at cutting values may not make that much difference, but you will notice it soon enough if your machine doesn't like it. Things might get a bit jerky at the rapid speeds. It just depends on how much control you have over the internal parameters on your controller.



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    Default Re: Techinical Diference between GO and G1

    hello bob, hello guys some details about okuma capabilities :

    rapid - trapezoidal chart + ipw palier; deceleration may begin sudden or progresiv
    feed - sharp corners of the rapid cinematic are replaced with radius
    * feeding at rapid speed will force the servos

    rapid - linear interpolated or not
    feed - always linear interpolated
    * not linear interpolated mode is faster

    rapid - more diff allowed
    feed - less diff allowed
    * diff increases with speed

    it is possible on some controls to change the transition dynamics between rapids and/or feeds :
    ... acceleration+exact_stop_window setings from parameters, available for input through display interface
    ... exact_stop_window setings are available :
    ...... for input also from code
    ...... as a common value for both rapid and feed, or
    ...... as separate values, one for rapids, and another for feeds ( depends )
    ... hicut option will smooth the transition between feed movements
    ... nubs option will interpolate an entire toolpath
    * hicut and nurbs can be edited in such a way, to deliver a desired balance between speed and precision

    and there are more things that tick

    i am sorry, but about OSAI Open-XS i dont have experience

    Quote Originally Posted by Closetguy View Post
    I would rather not get into a discussion about why
    please, i am interested; can you, or sombody else, share other examples, besides post5 ? or do you have ideas that could not perform in reality, because of cnc limitations, or whatever reason?

    about post #5, i have done a similar thing, for exactly the same reason as you described : cut down on machining time, machine wear, etc

    kindly !

    ps : GO vs G0 / nice one

    we are merely at the start of " Internet of Things / Industrial Revolution 4.0 " era : a mix of AI, plastics, human estrangement, powerful non-state actors ...


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    Default Re: Techinical Diference between GO and G1

    Quote Originally Posted by Closetguy View Post
    That is very interesting.
    Ac and Dec would almost be moot becase it would not be starting from a stand still or slowing to a stop.
    I plan on cutting at 25 to 30 meters/min and transition to 80 m/m for rapids. Should be pretty high up on the curve already.
    I am pretty sure I can change the Ac and Dec settings with code on the fly if I needed to.
    Not sure that it would require a full stop to take effect.
    My plan is to do a smooth lead in and a smooth "lead out" thus eliminating 2 full stops per part.
    Theoreticlly, this should cut down on machining time, machine wear and bit wear.
    What would you be cutting at 30meters /min and have rapids of 80meters /min, what machine do you have and what is your spindle max RPM, this will determine how fast you can cut

    Last edited by mactec54; 09-02-2017 at 01:05 PM.
    Mactec54


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Techinical Diference between GO and G1

Techinical Diference between GO and G1