please help with G132

[deadlykitten]

hello this code cuts 2 cw arches among the surface of a cilinder : 360-270* & 270-180*

problem is that only 1st G132 works, while 2nd shows attached funky error

however, if i put 1st G132 into brakets, than there is no error

please help ! kindly

 
    G50 S1900

    LRAD = 10
    LDIA = 100
    V1   = LRAD / [ VPAI * LDIA ] * 360

  ( * )

    G00 X500 Z250
    T0808
    M110
    SB = 1000 M13

    G119
 
    G00  X + LDIA
    G00  Z + LRAD C-V1
    G132 Z      0 C  0 L + LRAD F0.12 G95
    G132 Z - LRAD C-V1 L + LRAD F0.12 G95

    M02
 

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[deadlykitten]

hello, i simplified the code even more + attached image

i also sent it to my okuma rep / kindly

    G50 S1900

    G00 X500 Z250
    M110 T0808
    SB = 1000 M13 G119 F0.12 G95

    V1 = 10 / [ VPAI * VSIOX ] * 360

    G00  Z+10 C-V1 X50
    G132 Z  0 C  0 L10   ( it works only if i cancel this line )
    G132 Z-10 C-V1 L10 

    M02
 

[deadlykitten]

I think V1 calculation is wrong

hy kurmay, you are right : there was a mistake ... i tried to simplify the code that i shared, but i did no test it duuuh

i looked over your code from #3, and i noticed that you used M15, so i added it to my code, and voila, it works

thanks a lot man, you hit it

F[SB*0.2]

i guess you should execute it in G94



i looked also over the codes that you shared at #4 & #5; i did not tried to understand them, but thanks for your time to create those

now i will go to run some trials and create the comp codes / thx

[deadlykitten]

hello kurmay, after using G132, program duration reduced with cca 2seconds, and that is cool thanks again !


i also hit a case : for example the arch is among a cilinder o27.74, but tool is cutting at X7.5 ( attached image )

even if i wish the arch to be cut at o27.74, this won't happen, because tool position is 7.5, and 7.5<>27.74

to get it right, i needed to put also the tool at X27.74, and this would mean cutting with a lot of overhang

so i did a trick :

    NOEX VZSHX = - [ 27.74 - 7.5 ]
    G00 X27.74
    G132 etc
    NOEX VZSHX = 0

like this, the tool was positioned at X7.5, but the controller did the math like how it was at X27.74

there are also other methods to deliver this "trick"

if tool_X <> cilinder_diameter, then G132 won't perform as it should; like how G132 will deliver as expected only for engraving operations ( when tool cutting edge is positioned right on the cilinder )

---

there is a thing with your code; pls check this section from #3:

    G00   X170 Z0 C90
    G01   X152 F[SB*0.2]
    G01   Z0    C80 M16 G41

last line comands only the C axis ( from 90* to 80*; even if the program line does not modify the position of Z axis, Z will move because of the G41 ), and this requires a different feed; that movement, even if it is in feed, is not cutting, but is a simple positioning so to begin the compensation; but you may loose time because feed value is not correct

in other words, the cnc will generate the toolpath, but it won't travel among it at desired feed

to fix it, use this formula : feed_for_CZ_G94 = sqrt ( ( a ^ 2 + b ^ 2 ) / ( a ^ 2 + c ^ 2 ) ) * F, where :
... a = 360 * dz
... b = 500 * dc
... c = X * dc * pi
... F = desired feed in G94

dz&dc represents how much Z&C axis changes; they are always positive; if Z goes from 0 to -30, or to +30, in both cases, dz will be 30; same for dc

example 1 )
G00 Z0 C0 X100
G01 Z-10 F100 G94
in this case dz=10, dc=0 and X=100; do the math, calculate a b c; b & c will be 0, and the final result will be 1*F; so the correct feed will be F100, thus the code is correct

example 2 )
G00 Z0 C0 X33
G01 C-10 F100 G94
in this case dz=0, dc=10 and X=33; a will be 0; do the math, and the result will be ( 500 * 10 ) / ( 33 * 10 * 3.14 ) * 100 = 500*100/(33*3.14)=482; you need to rewrite the 2nd line like this G01 C-10 F482 G94

example 3 )
G00 Z0 C0 X50
G01 Z11 C45 F100 G94
in this case dz=11, dc=45 and X=50; write your 2nd line like this :
G01 Z11 C45 G94 F = sqrt ( ( (360 * dz) ^ 2 + (500 * dc) ^ 2 ) / ( (360 * dz) ^ 2 + (X * dc * pi) ^ 2 ) ) * 100
G01 Z11 C45 G94 F = sqrt ( ( (360 * 11) ^ 2 + (500 * 45) ^ 2 ) / ( (360 * 11) ^ 2 + (50 * 45 * 3.14) ^ 2 ) ) * 100

kindly sorry for the long reply, i tried to write it as short as possible ?!

[deadlykitten]

hy kurmay, if you shared those parametric examples at posts 4 & 5, then this is how i would code such pockets : toolpath inside a dwg ( attached image ), that i convert to G-code, and that code is inserted inside a general structure

to make it parametric like yours, then i would edit this code

comments are there to help locating each segment of the toolpath

i shared it to show that i use a soubroutine for shortest_path, and another to compute CZ feed; like this, i can edit it futher more, without worries about the need to change feed or to add M15,M16

code is pretty versatile: to put the pocket to another diameter, is enough to change LDIA value; it's fast, at least faster than recreating it inside a CAM / kindly

 

    NOEX V1 = 4000      ( n )
    NOEX V2 = 4*0.036   ( f )

  ( * )

    G50 S1900
    M867

    G00 X500 Z250
    M110 T+7*10101

    NOEX LDIA     = + 50                          ( cilinder dia 50    )
    NOEX VZSHX    = - [ LDIA - 40 ]               ( tool cuting at X40 )

    CALL OSUB

    NOEX VZSHX    =     0
    G00 X500 Z250 M12 M63

    M02

OSUB

    NOEX V3 = - 360 / VPAI / LDIA                 (*1)

    CALL OCAXS LV01 =                  -V3*[6]    (*2)

    SB=V1 M13 M08 G00 X+LDIA Z-42.286 C-V3*[6] M63 G95 G119

    G132  M15   Z = -44.286    C = -V3*[8]    F = V2   L2 ( arch intro )
    CALL OFCZT LZ = -60       LC = -V3*[8]   LF = V2      ( left       )
    G132  M16   Z = -62        C = -V3*[6]    F = V2   L2 ( corner 1   )
    CALL OFCZT LZ = -60       LC = +V3*[6]   LF = V2      ( up         )
    G132  M16   Z = -60        C = +V3*[8]    F = V2   L2 ( corner 2   )
    CALL OFCZT LZ = -15       LC = +V3*[8]   LF = V2      ( right      )
    G132  M15   Z = -13        C = +V3*[6]    F = V2   L2 ( corner 3   )
    CALL OFCZT LZ = -13       LC = -V3*[6]   LF = V2      ( down       )
    G132  M15   Z = -15        C = -V3*[8]    F = V2   L2 ( corner 4   )
    CALL OFCZT LZ = -46.286   LC = -V3*[8]   LF = V2      ( left       )
    G132  M16   Z = -48.286    C = -V3*[6]    F = V2   L2 ( arch exit  )

RTS ( . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . )

(*1) ( transformation factor, that allows converting a distance among cilinder perimeter into spindle phase )
(*2) ( soubroutine that helps indexing C axis among the shortest path )