[Kool Parts]

Need a little help from some of you lathe guys on this program.
When it gets to the G3 line it throws a fit. Just not familiar enough with the lathe yet to spot the problem.
Thanks,
Gary
G00 X-0.988 Z-2.6778
Z0.069
X-1.021
G01 X-1.036
Z-2.686
X-1.021
G00 X-1.003 Z-2.6778
Z0.069
X-1.036
G01 X-1.051
Z-2.686
X-1.036
G00 X-1.018 Z-2.6778
Z0.069
X-1.051
G01 X-1.066
Z-0.0893
G03 X-1.052 Z-0.131 K-0.0417 I-0.055
G01 Z-2.686
X-1.051
G00 X-1.033 Z-2.6778

[mariojl]

Hi Gary:
After figuring it out I found that your program can't work that way; it has three mistakes:
1) The I -0.055 is wrong, it must be positive.
2) The distance of starting point of the G3 to the I-K position calls for a 0.069 R. while at the end of it is not even and calls for a 0.062 R.
3) The command G3 must be G2
That means that probably your drawing is wrong or you calculated dim are.
Mario

[Kool Parts]

Mario,
Thanks for the input.
I guess the real question is will the Haas control allow you to machine on the Negative side of X0.0...
I am warming up the Ice box now and will try a few things.
Gary

[Machineit]

It is the relationships of XYZ and IJK that you need to understand. IJK are infact XYZ but they are the second calling in a line of code. In other words it's X=X1 and I=X2.

If you are making a move in the X+ direction, the I call will always be I-. This goes for XY and Z. That is because the IJK are the distances to the center of the arc from the ending position of the arc, and that will always be opposite direction of the end point.

This is definitely not my forte, I struggle with it always, but I'm trying. Gets even better when you add endmill radius' and tool tip radius.

Here it is from the manual:

Using I, J, K addresses:

I, J and K address are used to locate the arc center in relation to the start point. In other words, the I, J, K
addresses are the distances from the starting point to the center of the circle. Only the I, J or K specifi c to the
selected plane are allowed (G17 uses IJ, G18 uses IK and G19 uses JK). The X, Y, and Z commands specify
the end point of the arc. If the X, Y, or Z location for the selected plane is not specifi ed, the endpoint of the arc
is the same as the starting point for that axis.
To cut a full circle the I, J, K addresses must be used; using an R address will not work. To cut a full circle, do
not specify an ending point (X, Y and Z); program I, J or K to defi ne the center of the circle. For example: G02
I3.0 J4.0 (Assumes G17; XY plane)

Mike

[txcncman]

Based solely on your program, the numbers are wrong. Not sure how you came up with them. But they are wrong. Post a part print for more assistance.

[Machineit]

When I have trouble writing these I find that simply drawing the arc on paper and writing the start finish and center point locations makes it much easier to see how to write it.

This is really helpful with adding the radius's etc.. You will then see to add the tool nose radius etc. The locations have to be spot on or the control will reject it.

Many great programmers here, so post the move you need to make and they can help.

Mike

[mariojl]

[QUOTE=Machineit;
If you are making a move in the X+ direction, the I call will always be I-. This goes for XY and Z. That is because the IJK are the distances to the center of the arc from the ending position of the arc, and that will always be opposite direction of the end point.
[/QUOTE]

Hi Mike, excuse me, but please let me correct you, because your statement is contrary to the manual you cited.
The "I" is the relative distance from starting point to the center of the arc, and it can be either positive or negative, for depending the type of arc (concave or convex) that is cutting, the center of the arc may be above ( I+) or bellow (I-) the starting point.



Mario

[Kool Parts]

Hey thanks for the input guys. I appreciate it as I will have more stupid questions as move forward.
Without going into the whole story I had to change boring bars anyway so I started from scratch.
Changed the cad-cam post to output R. instead of I-K values. Now no problems.:banana:
Just trying to get as many questions under my belt before Tue when I will get my "training day" from the HFO.
I have a bunch of questions relating to the programing of the safety zone on the tail stock :tired:
Thanks,
Gary

[Machineit]

Hey thanks for the input guys. I appreciate it as I will have more stupid questions as move forward.
Without going into the whole story I had to change boring bars anyway so I started from scratch.
Changed the cad-cam post to output R. instead of I-K values. Now no problems.:banana:
Just trying to get as many questions under my belt before Tue when I will get my "training day" from the HFO.
I have a bunch of questions relating to the programing of the safety zone on the tail stock :tired:
Thanks,
Gary

That's great Gary. Have fun with the new machine!

The book is always pointing out that you can't do full circles with "R" moves, but of course two 180 deg "R" moves equals a full circle!

Mike

[angelw]

Hey thanks for the input guys. I appreciate it as I will have more stupid questions as move forward.
Without going into the whole story I had to change boring bars anyway so I started from scratch.
Changed the cad-cam post to output R. instead of I-K values. Now no problems.:banana:
Just trying to get as many questions under my belt before Tue when I will get my "training day" from the HFO.
I have a bunch of questions relating to the programing of the safety zone on the tail stock :tired:
Thanks,
Gary

Hi Gary,
Don't be too complaisant with the use of "R" format. As pointed out by mariojl, there are multiple reason why your original I,K format code didn't work, but at the end of the day, the control raised an alarm due to the arc end point not falling on the arc trajectory based on the given Start point and Arc Centre described by the I and K.

Now lets say that the your Start point and Arc Centre are correct and an error was made in calculating the end point. When using the "R" format, and when its geometrically possible, the control merely calculates a centre point to satisfy the given Start and End points. Accordingly, you can end up with an incorrectly shape part and not be aware, because no alarm is raised. You can't be any less accurate in your coordinate calculations when using the "R" format when a precise profile is required; "R" format just fudges the centre if you make a mistake with the Start and End point coordinates.

I understand that this is a Haas control being discussed, but the math involved will be the same as with a Fanuc control. Fanuc actually state in their programming manuals:

"If an arc having a central angle approaching 180 is specified with R, the calculation of the center coordinates may produce an error. In such a case, specify the center of the arc with I, J, and K".


Regards,

Bill

[Machineit]

Hi Gary,
Don't be too complaisant with the use o "R" format. As pointed out by mariojl, there are multiple reason why your original I,K format code didn't work, but at the end of the day, the control raised an alarm due to the arc end point not falling on the arc trajectory based on the given Start point and Arc Centre described by the I and K.

Now lets say that the your Start point and Arc Centre are correct and an error was made in calculating the end point. When using the "R" format, and when its geometrically possible, the control merely calculates a centre point to satisfy the given Start and End points. Accordingly, you can end up with an incorrectly shape part and not be aware, because no alarm is raised. You can't be any less accurate in your coordinate calculations when using the "R" format when a precise profile is required; "R" format just fudges the centre if you make a mistake with the Start and End point coordinates.

I understand that this is a Haas control being discussed, but the math involved will be the same as with a Fanuc control. Fanuc actually state in their programming manuals:

"If an arc having a central angle approaching 180 is specified with R, the calculation of the center coordinates may produce an error. In such a case, specify the center of the arc with I, J, and K".


Regards,

Bill

Ya, it's kinda like have an arc that just won't fit in a drawing, so you use a spline instead!

Mike