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  1. #21
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    Quote Originally Posted by essid.mh View Post
    How to calculate the optimal tolerance. No CAM software development company can answer to this question until now.
    I have the rethink and the algorithm that allows to identify the optimal tolerance and other mathematical models that can be programmed in CAM or post processor software in order to improve the high speed machining quality of freeform surface and increased the useful life of the CNC machine elements . Essid Mohamed . Teacher researcher . ISET SFAX and UGPMM. ENIS. Tunisia.
    https://www.linkedin.com/in/essid-mohamed-567865177/
    Mohamed ESSID | Ecole Nationale d'Ingenieurs de Sfax, Sfax | ENIS | Mechanical Engineering Department
    So how does this work then?
    I want to make the same part on 3x machines.
    #1 machine is a large Haas VF8 machine - a big heavy table with slow acceleration and deceleration.
    #2 machine is a much smaller Haas - smaller lighter table with the next generation faster processing control and much better acc/dec.
    #3 machine is a gantry design machine - the table is fixed and the axes are a bridge/portal design. So although mass of component on the table is irrelevant, unfortunately I have an issue with the X axis where there is "some" out of squareness to the Y.
    This has an early Fanuc control with no lookahead processing.

    How can you tell me what tolerances I can achieve on each machine please?

  2. #22
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    It’s amusing how many people always say how easy it is, then list off dozens of if’s and’s or but’s. Holding tight tolerance isn’t easy, hence all the special requirements to accomplish it. The best advice I read was to keep your head about you. Getting frustrated is a game changer for me! Best of luck

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  4. #23
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    Quote Originally Posted by essid.mh View Post
    How to calculate the optimal tolerance. No CAM software development company can answer to this question until now.
    I have the rethink and the algorithm that allows to identify the optimal tolerance and other mathematical models that can be programmed in CAM or post processor software in order to improve the high speed machining quality of freeform surface and increased the useful life of the CNC machine elements . Essid Mohamed . Teacher researcher . ISET SFAX and UGPMM. ENIS. Tunisia.
    https://www.linkedin.com/in/essid-mohamed-567865177/
    Mohamed ESSID | Ecole Nationale d'Ingenieurs de Sfax, Sfax | ENIS | Mechanical Engineering Department
    Thanks for posting this / these and will read your article with great interest,

    "Analytical modeling of the CNC machine axis motion in high-speed milling with local smoothing"

    Mohamed Essid1,2 & Bassem Gassara1 & Maher Baili3 & Moncef Hbaieb1,2 & Gilles Dessein3 & Wassila Bouzid Saï1


    Received: 26 March 2019 /Accepted: 10 July 2019

    # Springer-Verlag London Ltd., part of Springer Nature 201

    ________________________________

    Abstract

    In high-speed milling (HSM) of free-form surfaces, the tool path is mainly characterized by a set of short discontinuous segments in tangency. These discontinuities bring an intense kinematic parameter fluctuation of the computer numerical control (CNC) machine axes. The smoothing of the programmed tool path and the optimal choice of the manufacturing process parameters ensure a high productivity with the required quality of the machined surfaces. Precise estimation of the machining time allows an accurate evaluation of the machined product cost. Thereby, this is achieved by studying the effect of the tool path smoothing and the CNC controller parameters on the axis kinematics and the following errors. This paper focuses on the geometrical modeling of the local smoothing block adopted by Sinumerik CNC. Further, a kinematic model is proposed to simulate the axis motion in linear interpolation mode with local smoothing. The identification of the interpolator reduction effect on the programmed tolerance leads to the identification of the smoothing model adopted by the CNC unit. Then, the axis kinematic behavior is modeled while taking into account the drive parameter axes defined by the manufacturer of the CNC unit. The experimental results showed a smooth variation of the axis feed rate along the smoothing blocks and a good correlation with the proposed models.


    Keywords: Tool path setpoint . Interpolator . Following error . Hermit polynomial . Feed rate.


    ___________________________________


    @essid.mh ~ Some interesting references there esp. from the Siemens quarter.

    ___________________________________

    1. Siemens (2010) SINUMERIK 840D sl/828D basic functions function manual. Edition 03/2010

    2. Siemens (2009) SINUMERIK 5-axis machining. Edition 05/2009

    3. Fan W, Lee C-H, Chen J-H (2015) A realtime curvature-smooth
    interpolation scheme and motion planning for CNC machining of
    short line segments. Int J Mach Tools Manuf 96:27–46. https://doi.
    org/10.1016/j.ijmachtools.2015.04.009

    4. Sencer B, Ishizaki K, Shamoto E (2015) A curvature optimal sharp
    corner smoothing algorithm for high-speed feed motion generation
    of NC systems along linear tool paths. Int J Adv Manuf Technol 76:
    1977–1992. https://doi.org/10.1007/s00170-014-6386-2

    5. Zhao H, Zhu L, Ding H (2013) A real-time look-ahead interpolation
    methodology with curvature-continuous B-spline transition scheme
    for CNC machining of short line segments. Int J Mach Tools Manuf
    65:88–98. Redirecting

    6. Wang H, Wu J, Liu C, Xiong Z (2018) A real-time interpolation
    strategy for transition tool path with C2 and G2 continuity. Int J
    Adv Manuf Technol 98:905–918. https://doi.org/10.1007/s00170-
    018-2242-0

    7. Huang J, Du X, Zhu L-M (2018) Real-time local smoothing for
    five-axis linear toolpath considering smoothing error constraints.
    Int J Mach Tools Manuf 124:67–79. https://doi.org/10.1016/j.
    ijmachtools.2017.10.001

    8. Yang J, Hu Q, Ding H (2016) A two-stage CNC interpolation algorithm for corner smoothing trajectories with geometric error and dynamics constraints. Procedia CIRP 56:306–310. https://doi.org/
    10.1016/j.procir.2016.10.02

    9. Tulsyan S, Altintas Y (2015) Local toolpath smoothing for five-axis
    machine tools. Int J Mach Tools Manuf 96:15–26. https://doi.org/

    10.1016/j.ijmachtools.2015.04.01410. Yang J, Yuen A (2017) An analytical local corner smoothing algorithm for five-axis CNC machining. Int J Mach Tools Manuf 123:
    22–35. https://doi.org/10.1016/j.ijmachtools.2017.07.007

    11. Yan Y, Zhang L, Zhang K (2016) Corner smoothing transition algorithm for five-axis linear tool path. Procedia CIRP 56:604–609.

    https://doi.org/10.1016/j.procir.2016.10.119

    12. Bi Q, Shi J, Wang Y et al (2015) Analytical curvature-continuous
    dual-Bézier corner transition for five-axis linear tool path. Int J
    Mach Tools Manuf 91:96–108. https://doi.org/10.1016/j.
    ijmachtools.2015.02.002

    13. Shi J, Bi Q, Zhu L, Wang Y (2015) Corner rounding of linear fiveaxis tool path by dual PH curves blending. Int J Mach Tools Manuf
    88:223–236. https://doi.org/10.1016/j.ijmachtools.2014.09.007

    14. FANUC (2003) FANUC Series 30i/300i/300is-MODEL A user’s
    manual. Edition 2003

    15. Gassara B, Dessein G, Baili M et al (2013) Analytical and experimental study of feed rate in high-speed milling. Mach Sci Technol
    17:181–208. https://doi.org/10.1080/10910344.2013.780537

    16. Gassara B, Baili M, Dessein G et al (2013) Feed rate modeling in
    circular–circular interpolation discontinuity for high-speed milling.
    Int J Adv Manuf Technol 65:1619–1634. https://doi.org/10.1007/
    s00170-012-4284-z

    17. Gassara B, Dessein G, Baili M et al (2013) Kinematic behaviour
    modeling of the axes of a machining center in high speed milling.
    Adv Mater Res 698:39–48. https://doi.org/10.4028/www.scientific.
    net/AMR.698.39

    18. Pessoles X, Landon Y, Rubio W (2010) Kinematic modelling of a
    3-axis NC machine tool in linear and circular interpolation. Int J
    Adv Manuf Technol 47:639–655. https://doi.org/10.1007/s00170-
    009-2236-z

    19. Pessoles X, Redonnet J-M, Segonds S, Mousseigne M (2012)
    Modelling and optimising the passage of tangency discontinuities
    in NC linear paths. Int J Adv Manuf Technol 58:631–642. https://
    doi.org/10.1007/s00170-011-3426-z

    20. Suh S-H (2008) Theory and design of CNC systems. Springer,
    London

    21. Chen J, Ren F, Sun Y (2016) Contouring accuracy improvement
    using an adaptive feedrate planning method for CNC machine tools.
    Procedia CIRP 56:299–305. https://doi.org/10.1016/j.procir.2016.
    10.012

    22. Annoni M, Bardine A, Campanelli S et al (2012) A real-time
    configurable NURBS interpolator with bounded acceleration, jerk
    and chord error. Comput Aided Des 44:509–521. https://doi.org/10.
    1016/j.cad.2012.01.009

    23. Dong J, Wang T, Li B, Ding Y (2014) Smooth feedrate planning for
    continuous short line tool path with contour error constraint. Int J
    Mach Tools Manuf 76:1–12. https://doi.org/10.1016/j.ijmachtools.
    2013.09.009

    24. Pateloup. V (2005) Kinematics behavior improvement of high
    speed machine tool. Application to the tool path computation of
    pockets machining. PhD Thesis, Université BLAISE PASCAL –
    Clermont II

    25. Erkorkmaz K, Altintas Y (2001) High speed CNC system design.
    Part I: jerk limited trajectory generation and quintic spline interpolation. Int J Mach Tools Manuf 41:1323–1345. https://doi.org/10.
    1016/S0890-6955(01)00002-5


    __________________________________________________ __________________________________________-




    ^^^ Just a sketch of what @essid.mh is trying to go on about.

    @essid.mh not sure that (somewhat) inappropriately hijacking an old "Zombie" thread (that is substantially off topic to your purpose and topic) will serve you well or this forum


    However you might devise a new thread title that perhaps would stimulate discussion and interaction + perhaps be of the form of a question - a genuine question ?

    There's not really a specialized section or sub-forum for this kind of thing ?

    Defining what this kind of "thing" might be - might be a useful start ?

    There's no [ Shop-math / algorithms / engineering section ] sub-forum here ?


    _____________________________________

    General topic of reverse engineering proprietary algorithms on control and CAD/CAM systems for academic purposes comes to mind - (no judgement here as that is a common problem.).


    ____________


    May edit or clean up later on : Time willing.

  5. #24
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    Holding this tight of a tolerance can be done, but in reality, it won't be the tolerance that you produce with the tool, most likely. This tolerance will be achieved by hand sanding and perhaps polishing the part. Even with a really nice turned appearance, with a flat nose tool (like Iscar Cutgrip), the first couple of tenths (of an inch) will polish away in about 2 seconds. After that, it becomes serious effort to remove more material.

    I prefer to polish to achieve a stable fit, so this means turn to the high side of the tolerance window, or even a little higher (to avoid scrapping most of the parts). But this is never an easy (aka, cheap) task and will take a lot of stamina to do it all day for a day or two. You will need to become expert in 'reading' your emery cloth, which grit to use, how long to use it for, etc. It is still important to try to achieve maximum repetitive accuracy with your lathe. If it cannot repeat within a half thou consistently, you're in for a lot of hand work.

    Long parts that need a center support add another wrinkle to this, unless the center hole is drilled in the same chucking as the part is turned in. Any deviation of the center hole from true running will create taper on the part as the tailstock wobbles around doing its best to restore the position, but it cannot correct eccentricity within the degree of this small tolerance window. And this will make the diameter at the end of the part too small, and that effect will gradually diminish as your tool works towards the chuck. So you could be fighting tapering issues for this reason. I take the time to dial in the far end of long parts before inserting the tail center. This finicky process can take as long as machining the piece (on a CNC) but it's the way to produce fewer scrap parts.

    Edit: to dial in a long piece, you need minimal grip at the chuck end so that you can move the part readily with a mallet. This can be achieved with using a very short grip surface (1/4" long) in the chuck (or relieve a collet so only the front 1/4" does the gripping). However, if you can drill the center hole in place AFTER the chuck has already clamped, then you shouldn't need to worry about dialing anything in.

  6. #25
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    Quote Originally Posted by cameraman View Post
    Thanks for posting this / these and will read your article with great interest,

    "Analytical modeling of the CNC machine axis motion in high-speed milling with local smoothing"

    Mohamed Essid1,2 & Bassem Gassara1 & Maher Baili3 & Moncef Hbaieb1,2 & Gilles Dessein3 & Wassila Bouzid Saï1


    Received: 26 March 2019 /Accepted: 10 July 2019

    # Springer-Verlag London Ltd., part of Springer Nature 201

    ________________________________

    Abstract

    In high-speed milling (HSM) of free-form surfaces, the tool path is mainly characterized by a set of short discontinuous segments in tangency. These discontinuities bring an intense kinematic parameter fluctuation of the computer numerical control (CNC) machine axes. The smoothing of the programmed tool path and the optimal choice of the manufacturing process parameters ensure a high productivity with the required quality of the machined surfaces. Precise estimation of the machining time allows an accurate evaluation of the machined product cost. Thereby, this is achieved by studying the effect of the tool path smoothing and the CNC controller parameters on the axis kinematics and the following errors. This paper focuses on the geometrical modeling of the local smoothing block adopted by Sinumerik CNC. Further, a kinematic model is proposed to simulate the axis motion in linear interpolation mode with local smoothing. The identification of the interpolator reduction effect on the programmed tolerance leads to the identification of the smoothing model adopted by the CNC unit. Then, the axis kinematic behavior is modeled while taking into account the drive parameter axes defined by the manufacturer of the CNC unit. The experimental results showed a smooth variation of the axis feed rate along the smoothing blocks and a good correlation with the proposed models.


    Keywords: Tool path setpoint . Interpolator . Following error . Hermit polynomial . Feed rate.


    ___________________________________


    @essid.mh ~ Some interesting references there esp. from the Siemens quarter.

    ___________________________________

    1. Siemens (2010) SINUMERIK 840D sl/828D basic functions function manual. Edition 03/2010

    2. Siemens (2009) SINUMERIK 5-axis machining. Edition 05/2009

    3. Fan W, Lee C-H, Chen J-H (2015) A realtime curvature-smooth
    interpolation scheme and motion planning for CNC machining of
    short line segments. Int J Mach Tools Manuf 96:27–46. https://doi.
    org/10.1016/j.ijmachtools.2015.04.009

    4. Sencer B, Ishizaki K, Shamoto E (2015) A curvature optimal sharp
    corner smoothing algorithm for high-speed feed motion generation
    of NC systems along linear tool paths. Int J Adv Manuf Technol 76:
    1977–1992. https://doi.org/10.1007/s00170-014-6386-2

    5. Zhao H, Zhu L, Ding H (2013) A real-time look-ahead interpolation
    methodology with curvature-continuous B-spline transition scheme
    for CNC machining of short line segments. Int J Mach Tools Manuf
    65:88–98. Redirecting

    6. Wang H, Wu J, Liu C, Xiong Z (2018) A real-time interpolation
    strategy for transition tool path with C2 and G2 continuity. Int J
    Adv Manuf Technol 98:905–918. Error: DOI Not Found
    018-2242-0

    7. Huang J, Du X, Zhu L-M (2018) Real-time local smoothing for
    five-axis linear toolpath considering smoothing error constraints.
    Int J Mach Tools Manuf 124:67–79. Error: DOI Not Found.
    ijmachtools.2017.10.001

    8. Yang J, Hu Q, Ding H (2016) A two-stage CNC interpolation algorithm for corner smoothing trajectories with geometric error and dynamics constraints. Procedia CIRP 56:306–310. https://doi.org/
    10.1016/j.procir.2016.10.02

    9. Tulsyan S, Altintas Y (2015) Local toolpath smoothing for five-axis
    machine tools. Int J Mach Tools Manuf 96:15–26. https://doi.org/

    10.1016/j.ijmachtools.2015.04.01410. Yang J, Yuen A (2017) An analytical local corner smoothing algorithm for five-axis CNC machining. Int J Mach Tools Manuf 123:
    22–35. https://doi.org/10.1016/j.ijmachtools.2017.07.007

    11. Yan Y, Zhang L, Zhang K (2016) Corner smoothing transition algorithm for five-axis linear tool path. Procedia CIRP 56:604–609.

    https://doi.org/10.1016/j.procir.2016.10.119

    12. Bi Q, Shi J, Wang Y et al (2015) Analytical curvature-continuous
    dual-Bézier corner transition for five-axis linear tool path. Int J
    Mach Tools Manuf 91:96–108. Error: DOI Not Found.
    ijmachtools.2015.02.002

    13. Shi J, Bi Q, Zhu L, Wang Y (2015) Corner rounding of linear fiveaxis tool path by dual PH curves blending. Int J Mach Tools Manuf
    88:223–236. https://doi.org/10.1016/j.ijmachtools.2014.09.007

    14. FANUC (2003) FANUC Series 30i/300i/300is-MODEL A user’s
    manual. Edition 2003

    15. Gassara B, Dessein G, Baili M et al (2013) Analytical and experimental study of feed rate in high-speed milling. Mach Sci Technol
    17:181–208. https://doi.org/10.1080/10910344.2013.780537

    16. Gassara B, Baili M, Dessein G et al (2013) Feed rate modeling in
    circular–circular interpolation discontinuity for high-speed milling.
    Int J Adv Manuf Technol 65:1619–1634. https://doi.org/10.1007/
    s00170-012-4284-z

    17. Gassara B, Dessein G, Baili M et al (2013) Kinematic behaviour
    modeling of the axes of a machining center in high speed milling.
    Adv Mater Res 698:39–48. https://doi.org/10.4028/www.scientific.
    net/AMR.698.39

    18. Pessoles X, Landon Y, Rubio W (2010) Kinematic modelling of a
    3-axis NC machine tool in linear and circular interpolation. Int J
    Adv Manuf Technol 47:639–655. Error: DOI Not Found
    009-2236-z

    19. Pessoles X, Redonnet J-M, Segonds S, Mousseigne M (2012)
    Modelling and optimising the passage of tangency discontinuities
    in NC linear paths. Int J Adv Manuf Technol 58:631–642. https://
    doi.org/10.1007/s00170-011-3426-z

    20. Suh S-H (2008) Theory and design of CNC systems. Springer,
    London

    21. Chen J, Ren F, Sun Y (2016) Contouring accuracy improvement
    using an adaptive feedrate planning method for CNC machine tools.
    Procedia CIRP 56:299–305. https://doi.org/10.1016/j.procir.2016.
    10.012

    22. Annoni M, Bardine A, Campanelli S et al (2012) A real-time
    configurable NURBS interpolator with bounded acceleration, jerk
    and chord error. Comput Aided Des 44:509–521. https://doi.org/10.
    1016/j.cad.2012.01.009

    23. Dong J, Wang T, Li B, Ding Y (2014) Smooth feedrate planning for
    continuous short line tool path with contour error constraint. Int J
    Mach Tools Manuf 76:1–12. https://doi.org/10.1016/j.ijmachtools.
    2013.09.009

    24. Pateloup. V (2005) Kinematics behavior improvement of high
    speed machine tool. Application to the tool path computation of
    pockets machining. PhD Thesis, Université BLAISE PASCAL –
    Clermont II

    25. Erkorkmaz K, Altintas Y (2001) High speed CNC system design.
    Part I: jerk limited trajectory generation and quintic spline interpolation. Int J Mach Tools Manuf 41:1323–1345. https://doi.org/10.
    1016/S0890-6955(01)00002-5


    __________________________________________________ __________________________________________-




    ^^^ Just a sketch of what @essid.mh is trying to go on about.

    @essid.mh not sure that (somewhat) inappropriately hijacking an old "Zombie" thread (that is substantially off topic to your purpose and topic) will serve you well or this forum


    However you might devise a new thread title that perhaps would stimulate discussion and interaction + perhaps be of the form of a question - a genuine question ?

    There's not really a specialized section or sub-forum for this kind of thing ?

    Defining what this kind of "thing" might be - might be a useful start ?

    There's no [ Shop-math / algorithms / engineering section ] sub-forum here ?


    _____________________________________

    General topic of reverse engineering proprietary algorithms on control and CAD/CAM systems for academic purposes comes to mind - (no judgement here as that is a common problem.).


    ____________


    May edit or clean up later on : Time willing.
    You've earnt your money here

    He did post on eMastercam with an enhanced version.
    Attached Thumbnails Attached Thumbnails capture.jpg  


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