I's & J's

[boomer187um]

what are the I's and J's in my code?

G90
M99:WJET
G00X10.328Y4.25
M04
F240.
G02X10.328Y4.25I10.J4.25
M03
G00X14.394Y5.934
M04
F240.
G02X14.394Y5.934I14.066J5.934
M03
G00X16.078Y10.
M04
F240.
G02X16.078Y10.I15.75J10.
M03
G00X14.394Y14.066
M04
F240.
G02X14.394Y14.066I14.066J14.066
M03
G00X10.328Y15.75
M04
F240.
G02X10.328Y15.75I10.J15.75
M03
G00X6.262Y14.066
M04
F240.
G02X6.262Y14.066I5.934J14.066
M03
G00X4.578Y10.
M04
F240.
G02X4.578Y10.I4.25J10.
M03
G00X6.262Y5.934
M04
F240.
G02X6.262Y5.934I5.934J5.934
M03
G00X14.406Y10.
M04
F240.
G02X14.406Y10.I10.J10.
M03
G00X12.736Y19.541
M04
F240.
G01X12.756Y19.612
G02X12.955Y19.553I10.J10.
G02X13.325Y19.01I12.829J19.07
G03X15.55Y18.228I14.54J18.91
G01X15.592Y18.29
G02X15.762Y18.173I10.J10.
G02X15.947Y17.541I15.493J17.751
G03X17.821Y16.111I17.071J17.071
G01X17.88Y16.156
G02X18.006Y15.992I10.J10.
G02X17.986Y15.335I17.619J15.675
G03X19.327Y13.395I18.91J14.54
G01X19.397Y13.42
G02X19.466Y13.225I10.J10.
G02X19.244Y12.606I19.J13.042
G03X19.919Y10.346I19.877J11.564
G01X19.994Y10.349
G02X19.999Y10.142I10.J10.
G02X19.596Y9.622I19.5J10.112
G03X19.541Y7.264I19.877J8.436
G01X19.612Y7.243
G02X19.553Y7.045I10.J10.
G02X19.01Y6.675I19.07J7.171
G03X18.228Y4.45I18.91J5.46
G01X18.29Y4.408
G02X18.173Y4.238I10.J10.
G02X17.541Y4.053I17.751J4.507
G03X16.111Y2.178I17.071J2.929
G01X16.156Y2.12
G02X15.992Y1.994I10.J10.
G02X15.335Y2.014I15.675J2.38
G03X13.395Y.673I14.54J1.09
G01X13.42Y.603
G02X13.225Y.534I10.J10.
G02X12.606Y.756I13.042J1.
G03X10.346Y.08I11.564J.123
G01X10.349Y.006
G02X10.142Y.001I10.J10.
G02X9.622Y.403I10.112J.5
G03X7.264Y.459I8.436J.123
G01X7.243Y.387
G02X7.045Y.446I10.J10.
G02X6.675Y.99I7.171J.93
G03X4.45Y1.771I5.46J1.09
G01X4.408Y1.71
G02X4.238Y1.827I10.J10.
G02X4.053Y2.459I4.507J2.248
G03X2.178Y3.889I2.929J2.929
G01X2.12Y3.843
G02X1.994Y4.008I10.J10.
G02X2.014Y4.665I2.38J4.325
G03X.673Y6.605I1.09J5.46
G01X.603Y6.58
G02X.534Y6.775I10.J10.
G02X.756Y7.394I1.J6.957
G03X.08Y9.654I.123J8.436
G01X.006Y9.651
G02X.001Y9.858I10.J10.
G02X.403Y10.378I.5J9.888
G03X.459Y12.736I.123J11.564
G01X.387Y12.756
G02X.446Y12.955I10.J10.
G02X.99Y13.325I.93J12.829
G03X1.771Y15.55I1.09J14.54
G01X1.71Y15.592
G02X1.827Y15.762I10.J10.
G02X2.459Y15.947I2.248J15.493
G03X3.889Y17.821I2.929J17.071
G01X3.843Y17.88
G02X4.008Y18.006I10.J10.
G02X4.665Y17.986I4.325J17.619
G03X6.605Y19.327I5.46J18.91
G01X6.58Y19.397
G02X6.775Y19.466I10.J10.
G02X7.394Y19.244I6.957J19.
G03X9.654Y19.919I8.436J19.877
G01X9.651Y19.994
G02X9.858Y19.999I10.J10.
G02X10.378Y19.596I9.888J19.5
G03X12.754Y19.613I11.564J19.877
M03
G00X9.858Y19.999
M04
F240.
G02X10.378Y19.596I9.888J19.5
M03
M30

[tex]

They are very likely to be circular interpolation codes.

[mrainey]

http://www.nfrpartners.com/nfrg2g3.htm

[FarmerDK]

Hey boomer187um !
post #3 has all you need.

What i failed to notice on my job is:
"...No - we've probably forgotten something. But that's why CNC programmers make those big bucks."

[underdog]

the I's J's and K's are coordinates that match up with X, Y and Z respectively, and , depending on how your controller uses them, they are either; 1) the distance from the STAR of the arc to the Center of the arc you are cutting, OR 2) the coordinates of the center of the arc you are cutting. If they seem like crazy, odd numbers then they are probably number 1 above. CHeck your controller handbook to see what your controller is expecting.

[Geof]

I's and J's I can understand but the program is for a waterjet cutter and has M03 and M04 which to me are spindle forward and spindle reverse. What the **** does M04 do on a water jet? Suck the water back up!!! That would be a trick.

[boomer187um]

M04 is water on, M03 is water off

[HuFlungDung]

Underdog,
Your point#1 is something I have never seen: the machine is always positioned at the start of the arc (obviously), so the G02 or G03 code contains the XY coordinates of the endpoint after the arc is traversed, and I and J are the XY coordinates of the arc center. That being said, the arc center coordinates are sometimes reckoned as absolute coordinates (relative to the part X0Y0), but more often, they are reckoned as incremental coordinates relative to the start point (current position) of the machine. If that's what you meant, then good

[Geof]

Originally Posted by boomer187um M04 is water on, M03 is water off

Yes I had figured that but I think it is ridikulus (to quote Harry Potter). If someone trained on a water jet machine transferred to cnc mill or lathe and used M04 to start the spindle life could get interesting; most cutters prefer to run forwards. It is frustrating that all the different manufacturers could not agree on standards that are truly universal; like this and whether the I's and J's are going to be interpreted in incremental or absolute. The situation is something like it was with fasteners before unified threads when everyone had their own threads so their customers were trapped for parts and service.

[underdog]

HuFlungDung,

I think we're saying the same thing aren't we? Its seems the machine builders have gone in 'generations' - I worked on one ancient machine that was ONLY incremental - Yuk! Then there was absolute and the programmers looked on it and said it was good, but the I's and J's were still incremental distances from the start of the arc to the arc center ( we're talking slightly less ancient machine now). Then the I's and J's became the absolute coordinates of the arc center (making more sense now- and easier to do standing at the machine) and finally, probably in response to howls of anguish from us - we have the R radius value. Thats how I've seen it unfold.

[mrainey]

I can only recall personally using a few controls that allowed absolute coordinates for arc centers - specifically the old Bridgeport BOSS 5, the G & L 2300, and some of the older Cincinnati Milacron models (cut me some slack, it's been a while). I'm sure there are more - what are others you've used?

I remember some older controls ( late 70's - early 80's) such as Okuma 2200's and Fanuc 6's using signed incremental distance from start point to center point. I think the Fanuc already had the option for the R. The Bendix 5 control on a Monarch VMC75 I worked with used the unsigned incremental distance, as I remember.

For manual programming, I never saw an advantage in the R or the absolute coordinates over the IJ/IK method. You had to calculate the two legs of the triangle with any of the methods to get all the info you needed to determine the start and end points, plus location of the arc center.

Variety in available features and programming styles is definitely the theme in CNC.

[wisp]

On our new deckel maho mills with a heidenhein controls, i,j,k is an absolute X,Y,Z coordinate for center of arc.

on our mazaks, its an incremental distance from the start of the arc to then end

on our mori seiki's it and incremental distance from the start of the arc to the center of the arc.

welcome to the frustrating world of programming.