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Thread: Diagonal Hobbing

  1. #13
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    Default Re: Diagonal Hobbing

    hello again, please check attached image long story short : sync zy

    the time required for real trials on that multus-u4000 is much shorter than the time that i need to fully understand this kind of process and develop sharp code

    if the hob is spinned directly by M axis ( like and end-mill ) , i recomand using the hob in the area near the tool shank, for better cutting rigidity

    when wear appears, simply move towards the top ( maybe also reduce cutting specs ), so a fresh row of teeth will be delivering the finished surface

    i may be wrong, since flipping the tool requires reversed sense of the M axis, and it may possible that a new tool could not be used towards the shank, but only towards the top, so a bit of rigidity will be lost, but it may be just fine; kindly

    Attached Thumbnails Attached Thumbnails Diagonal Hobbing-01-png  
    Last edited by deadlykitten; 11-10-2017 at 07:57 AM.
    Ladyhawke - My Delirium, https://www.youtube.com/watch?v=X_bFO1SNRZg


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    Quote Originally Posted by deadlykitten View Post
    hello again, please check attached image long story short : sync zy

    the time required for real trials on that multus-u4000 is much shorter than the time that i need to fully understand this kind of process and develop sharp code

    if the hob is spinned directly by M axis ( like and end-mill ) , i recomand using the hob in the area near the tool shank, for better cutting rigidity

    when wear appears, simply move towards the top ( maybe also reduce cutting specs ), so a fresh row of teeth will be delivering the finished surface

    i may be wrong, since flipping the tool requires reversed sense of the M axis, and it may possible that a new tool could not be used towards the shank, but only towards the top, so a bit of rigidity will be lost, but it may be just fine; kindly
    On this machine "X" is up and down... "Y" is front to back, z is left to right.

    And what u said about moving to a new row of teeth when it becomes dull is exactly what i want to do. But i dont want to shift it occasionally, i want it to shift and use the entire length of the tool every pass/part. Thats why its called diagonal hobbing. It increases tool life, uses all the teeth on cutter, and its also the method for creating "taper root splines" by means of a conical hob tool.

    Heres the unedited code straight off the multus using the conversational gear software.

    Attached Files Attached Files


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    Default Re: Diagonal Hobbing

    Note that the name "taper spline" does not reflect the actual code. Its what i named it, the code produces no taper whatsoever.

    I realize this is a difficult mess to wrap your head around. Even when its right in front of u.. its kept me up at night and been on my mind constantly bc challenges like this is why i chose the trade... I will get this done or scrap every part trying.
    Im not currently setup on this job but it will be back aroundin the near future. The guys that are doing the spline for us are 600 miles away and really sticking it to us on an order of these, from what im told anyway.



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    Default Re: Diagonal Hobbing

    On this machine "X" is up and down... "Y" is front to back, z is left to right
    hello corey i think i know how this axis are named; a normal lathe has XZ, and Y is an option

    moving to a new row of teeth when it becomes dull is exactly what i want to do. But i dont want to shift it occasionally, i want it to shift and use the entire length of the tool every pass/part.
    this is how i see things : tool has active length of 100%; when tool cuts, it uses only 10% of its active length, and this 10% is moving between 0% and 60% ( or 60%-0% ) as the turret is moving to left

    after a while, wear occurs, so is no longer possible to use 0-60%, but [0+5]-[60+5]%, where 5% represents the portion of a new row of teeth

    i dont know exactly if you must go from bigger diameter to the smaller diameter among the tapered tool, or viceversa, but tool requires feed among Y among a certain portion, and this portion may be shifted as wear occurs i hope that i explained it well

    *all numbers used are theoreticall

    i want it to shift and use the entire length of the tool every pass/part
    i dont think that you should wish for this / if the process requires a tool with an active length AL=n, than the real tool must have AL=n+2*clearance, so to have a bit of comfort

    the longer the tool, more comfort created, but also rigidity is lost

    Heres the unedited code straight off the multus using the conversational gear software
    i have not yet open that file; all i need is just the code outputed for a simple ( cilindrical ) hob, for a single Z pass

    after that, we can develop

    if the code is created for this tapered hob, but it does not perform well, than onestly, i dont think that it is a good idea to remove errors and add good code; i simply wish to develop from a good working code

    also, i am not sure if i will succed, but i will try

    its kept me up at night and been on my mind constantly
    there are better ways to have white nights

    Note that the name "taper spline" does not reflect the actual code. Its what i named it ...
    i am really waiting for the day when i will simply create a file with a particular name, without any content at all, and the cnc will machine parts

    i would call it : just_get_it_done_and_clean_yourself_and_do_whatever_without_letting_me_know.go_now

    Last edited by deadlykitten; 11-10-2017 at 02:34 PM.
    Ladyhawke - My Delirium, https://www.youtube.com/watch?v=X_bFO1SNRZg


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    Quote Originally Posted by deadlykitten View Post
    ; all i need is just the code outputed for a simple ( cilindrical ) hob, for a single Z pass
    thanks for your time! Much appreciated...
    Yes that code in the file is for a simple hob with one z pass. That is all the machine will output.

    However, i "think" in could be edited to feed in both x & z at the same time... on this particular machine and part, y is only used for an approach or retract, the variation in tooth depth will and must come from the big to small diameter change of the cutter as it travels to the left in z and upwards in "x". Y is to remain fixed other than lead in/out of the cut.

    The cutter has extra markings on it from a normal hob. Has 2 diameters and an extra "L"...

    Attached Thumbnails Attached Thumbnails Diagonal Hobbing-conicalhob_end-jpg   Diagonal Hobbing-conicalhob_side-jpg  


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    Default Re: Diagonal Hobbing

    good day corey you desire for extra movement on X, while i thougth of Y

    if hob position, relative to M spindle axis, is :
    ... coaxial ( just like an endmill ), than X is required ( i guess this is your real setup )
    ... perpendicular ( just like when using an attachement ), than Y is required ( this is what i have imagined : hob suport from both ends )

    i will look soon over your code / kindly

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


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    Default Re: Diagonal Hobbing

    Quote Originally Posted by deadlykitten View Post
    ... coaxial ( just like an endmill ), than X is required ( i guess this is your real setup )
    if this is your case, and you have allready feed X axis ( and it wiped the teeth ), than it simply means that it was a wrong ratio

    i dont know how to compute the ratio between the 2 linear feeds, but last video that i shared show the process that you need, so maybe the guys that posted it can provide the answer

    Last edited by deadlykitten; 11-11-2017 at 10:17 AM.
    Ladyhawke - My Delirium, https://www.youtube.com/watch?v=X_bFO1SNRZg


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    Default Re: Diagonal Hobbing

    hello after my own math, which i can not test it, ( pls find attached draw ), i would recomand a 2nd feed travel of 64.776mm, coresponding to a 1st feed travel of 63.094mm(=2.484inch) so to achieve a part with 3.279 degress taper, using a hob with 3.199 degress taper

    what is the length of your hob ? is it at least 65mm ?

    at this stage, i would measure the conicity of the hob ( because this approach is based on that value ), compute a 2nd feed travel, and do a part

    i still have no clue about :
    ... the theory about how to compute the exact ratio
    ... how the cnc syncs M&S ( initialty i thought it is flat turn, but now i doubt it )

    Attached Thumbnails Attached Thumbnails Diagonal Hobbing-01-jpg  
    Last edited by deadlykitten; 11-12-2017 at 05:03 AM.
    Ladyhawke - My Delirium, https://www.youtube.com/watch?v=X_bFO1SNRZg


  9. #21
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    Default Re: Diagonal Hobbing

    hello, i have looked over your code this is where X movements can be implemented :

    Code:
    (CUT PASS)
    OCUT
    SB=SRPM M14
    X=HSIF             ( X=X_start )
    G01 Z=ZSTA+ZCL1 F=FAPR G94
    G01 Y=YPOS*[[PIND/2]+[CUTD/2]-DDEP] F=FAPR G94
    G95
    F=FEED
    G01 Z=ZEND-ZCL2    ( X=X_end )
    G00 Y=YPOS*[[PIND/2]+[CUTD/2]+YAPR]
           Z=ZSTA+ZAPR ( X0 )
    M164
    M01
    RTS

    please, what is the purpose of this comment : (INTERRUPT SUBROUTINE) + (ACTIVATED BY YELLOW BUTTON) ?


    also there are many unnecessary movements that can be eliminated, etc, but i consider the ratio problem more important; once the ratio will be fixed, maybe i will rewrite that code ( for posterity's sake, etc )


    please excuse me for repeating : the ratio key is inside the tapered hob ( thus measuring it should provide an idea ); also these guys, i think, can provide an answer : M.T. S.r.l. – Produzione moduli rotanti

    kindly

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


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    Default Re: Diagonal Hobbing

    MS sync methods :
    ... flat turn : master spindle = S
    ... M556 : master spindle = M

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


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    Default Re: Diagonal Hobbing

    [ sugestion for measuring the hob taper angle ]

    hobe taper angle is represented in image 1 with blue lines; i need this value ( or data that can lead to this value ), so to provide a ratio, which i hope it will work i am not sure, but i think it will work ...

    the hobe itsself is a part; if we consider removing from it the geometry marked with yellow, the result is a conical end mill, capable only for side machining, and not for face machining

    i made the analogy between hob and end-mill so to make it easier to locate the needed geometry, etc ...



    image 2, drawing 1 : lets consider the hob slided on an arbor, until it hits a shoulder; this arbor is rotated directly by the M spindle ( i guess this is your real setup, or maybe close to it )

    image 2, drawing 2 :
    ... remove the hob from the arbor, without removing the arbor from the spindle
    ... check arbor tirr in 2 places, so to have an idea
    ... also make sure that the arbor axis is paralel to X axis ( adjust B head to be paralel with X axis )
    ... by B head, i mean that horse head that is inside the multus

    image 2, drawing 3 :
    ... when arbor is checked to be paralel to X axis, and arbor tirr is good, put the hob on the arbor
    ... the play between the arbor and the hob should be something arround tolerance=0.02; so to make it is possible to put in ( or take out ) the hob by hand, with normal effort, and without putting stress on the B head; the arbor should have a thread at the end, so after the hob is slided, just use a nut ( or a screw ) to secure it, not to fall down; this nut ( or screw ) should be torqued very light, only to secure the hob not to fall, thus there should not be used high torque, like when securing the tool against cutting forces; in this stage is not required to be used that thing that goes inside the zone marked in image 2b; in this stage the assamble should be tighten soft, with a gentle hand, not to be secured for cutting forces, but only enough not to fall apart when measuring
    ... check the tirr on the hob, just like on the arbor; the [ hob tirr ] should be close to [ arbor tirr ] + [ less than the play between arbor and hob ]

    image 2, drawing 4 :
    ... take a dial indicator with a magnetic base
    ... magnetic base on the chuck and dial on the hob
    ... in this stage it is important to avoid extra precision when using the dial, otherwise precious time will be lost
    ... please use this tips :
    ...... the angle between dial axis and a horizontal ( or Z axis ) can be 10 .. 15 degrees without worries
    ...... the dial axis is not required to be contained inside [ ZX ] plane; it can make 20 degress without worries
    ...... the dial axis is not required to intersect the hob centerline
    ...... the dial axis is not required to be perpendicular on the hob taper
    ......... in other words, is enough to make contact and just have a position which is subject to common sense
    ... for best results, from now on :
    ...... always rotate the hob in same sense; do not reverse sense
    ...... always feed the X axis from top to bottom, or viceversa; do not revere sense
    ......... sense reversing will lead to extra forces on the dial indicator, making it to lose precision
    ...... always make sure that the dial is armed at same value; i would recomand 0.3 - 0.5; if, for example, 0.43 is chosen, than never go over 0.43; if somehow 0.47 is reached, go back to 0.2, and after that back again towards 0.43 ( thus no dial reversing )
    ... rotate the hub to make sure that the heighest point is reached ( shown in image 3 )

    measure like this, along the taper, 4..6 points; dial should always show same value

    take a photo of the cnc screen, coresponding to each measurement, and send them to me if you wish, you may use a program that records axis position from the cnc and saves them to a file

    kindly

    Attached Thumbnails Attached Thumbnails Diagonal Hobbing-01-jpg   Diagonal Hobbing-02-jpg   Diagonal Hobbing-2b-png   Diagonal Hobbing-03-jpg  

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


  12. #24
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    Default Re: Diagonal Hobbing

    You're on the right track and that is my hob/arbor setup, except that it is reversed... large end of hob is toward "top" of machine. the cutter will start into workpiece at full depth first then fade away in x positve and z negative movements. Mainly so the b horse head is moving up and away from chuck (other than z- move). i have to make this a safe dummy proof setup so i dont make things too hard on myself when i train the next operator on this job! But im years from that now... it will take some time to get your requested info. This machine hasn't sit idle since we got it in april. Thanks for the help and im amazed by the fast response! I think the hob angle u want is on the cutter but it doesn't hurt to double check i suppose.



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