Fanuc 16ia cutter comp parameter - cutter comp in a "straight line toolpath"

[dandrummerman21]

Sorry for the terrible title, I wasn't sure how to explain it in a few words.

So I have a part that has a woodruff key cut into it, and I wanted to use cutter comp to adjust the depth. The tool is a woodruff keycutter, and I am plunging straight into the shaft in the Y direction.

I thought this was possible but the machine doesn't move as expected and I didn't see a relavent parameter.

Here is my code:

G0G55X1.38Y-.85S300M3
G43H5Z.1M8
G1Z-.4365F50
G1G41D5Y-0.506F1.5 (I want this to go further with a cutter comp adjustment)
G4X1
G40G1Y-.85F20.
G0Z5.M9


So If i put in a -.005 value in for cutter comp, it will move over .005" in X over the length of the move. Since the next movement is straight back out in Y, I expected it to not move sideways but instead go further in Y only.

I tried removing the dwell and having the next block be a Y move but it did not work.

Is this possible? Or am I stuck doing it other ways (such as modifying code, or using macro variables in my program)

 

[BajaFire]

Can you turn on cutter comp outside the part? Usually a change in direction (X to Y or Y to X) is required for cutcom to activate
G0G55X1.5Y-.85S300M3
G43H5Z.1M8
G1Z-.4365F50
G1 G41 D5 X1.38 F1.5
Y-.506
G4X1.
Y-.85
X1.5G40

 

[dandrummerman21]

Thanks for your reply. I just tried that.

So what that does is brings the tool to X1.385 (which I don't really want), then it goes up to Y-.501 (which i do want).

But when it comes out of the slot, the machine immediately feeds X to X1.375 and feeds back out at the same time. So that's a no-go.

I have edited the program for now, I need the parts to run. This keycutter is a resharp but I will be putting brand new ones in in the future, so I want to still be able to simply use cutter comp if possible.

 

[EmGo]

From what I understand of your explanation, you are trying to use an undersized keyseat cutter to cut a keyseat - like a .425" cutter to do a .5" keyseat, yes ?

In order to do this, your undersized cutter needs to move in an arc. Cutter comp can't just make a smaller cutter bigger. Imagine that you have a 4" radius arc on a part and you will cut it with a 1" end mill. The path of the end mill will be .5" away from the arc on the part. If you use a .5" dia end mill, then the path will be .25" away from the described part arc.

That's what cutter comp does, it adjusts the toolpath to account for the actual size of the cutter, as opposed to the programmed cutter size.

So to do what you want to do, you can't just tell it "G41 and plunge". You have to give it a toolpath, add the comp value while the tool is moving along that path, then later on remove that value. I don't think you can add a G41 while on an arc but don't know fanuc very well. Normally you would add or subtract the comp while travelling on a straight line towards the cut.

So write a path that looks like a teardrop from your set point. Add the comp while travelling along the straight line towards the keyseat arc in the shaft, then arc around the keyseat, then remove the comp while travelling along another straight line back to your set point.

If you use the correct cutter later you will want to remove all this mickeymouse crap but for figuring it out now ...

If my stupid vmware license hadn't timed out I could draw it for you but ... sorry. I despise software. Or the companies who implement it, actually. Software should be free, I'm sick of their shit.

 

[dandrummerman21]

From what I understand of your explanation, you are trying to use an undersized keyseat cutter to cut a keyseat - like a .425" cutter to do a .5" keyseat, yes ?

No.

Woodruff keyseat cutters are usually about .015" bigger than nominal. In this case, it's a 3/4 keyseat cutter, which the print says can be .750/.768 diameter. My brand new one is about .765. The resharpened one in the machine is about .755

There is a dimension from bottom of radius to other side of the shaft that I need to hit.

I am not interpolating the radius. Just plunging straight in and straight out. I wanted cutter comp to just elongate the Y travel of my cutter, but instead it applies compensation in X over the length of my travel, which I do not want.

All i did to get it working (right now) is change -.506 to -.501. The next time we change tools, it might be a brand new one, we'll need to change it back in the code. Yes, it is easy to change the code, but I thought I could accomplish it with cutter comp, which all of my operators understand the use of, hence the parameter question.

 

[EmGo]

I wanted cutter comp to just elongate the Y travel of my cutter, but instead it applies compensation in X over the length of my travel, which I do not want.

It doesn't care what you want It's not designed to do that.

 

[dandrummerman21]

Sure, thanks.

 

[rklopp]

It sounds like you need a short segment of contour at the bottom of the keyway where the segment is parallel to the shaft. Otherwise, there's nothing for the cutter to compensate off of. You might be able to get this to work by programming a path like a square-bottom U shape (the dashed line below), where the bottom of the U is at the depth you want and the two legs are equidistant from the centerline of the keyway by the radius of the cutter (the red thing) plus 0.001 or whatever is the shortest move your control will allow. If I misunderstood what you are trying to do, I apologize.

 

[angelw]

So I have a part that has a woodruff key cut into it, and I wanted to use cutter comp to adjust the depth. The tool is a woodruff keycutter, and I am plunging straight into the shaft in the Y direction.

I thought this was possible but the machine doesn't move as expected and I didn't see a relavent parameter.

Here is my code:

G0G55X1.38Y-.85S300M3
G43H5Z.1M8
G1Z-.4365F50
G1G41D5Y-0.506F1.5 (I want this to go further with a cutter comp adjustment)
G4X1
G40G1Y-.85F20.
G0Z5.M9


So If i put in a -.005 value in for cutter comp, it will move over .005" in X over the length of the move. Since the next movement is straight back out in Y, I expected it to not move sideways but instead go further in Y only.

I tried removing the dwell and having the next block be a Y move but it did not work.

Is this possible? Or am I stuck doing it other ways (such as modifying code, or using macro variables in my program)

The control is doing exactly what you're asking it to do. You can do what you want to do by creating pseudo Cutter Radius Compensation in the following manner:

G0G55X1.38Y-.85S300M3
G43H5Z.1M8
G1Z-.4365F50
D01
G1Y[-0.506+#[12000+#4107]]F1.5 (I want this to go further with a cutter comp adjustment)
G4X1
G1Y-.85F20.
G0Z5.M9

In the above example where D01 is specified, #[12000+#4107] will equate to #12001, which is the System variable for the first Wear Offset for Cutter Radius Comp if your control is using tool compensation memory C. You will have to determine what tool compensation memory your machine is equipped with so that the correct System Variable is used.

All i did to get it working (right now) is change -.506 to -.501. The next time we change tools, it might be a brand new one, we'll need to change it back in the code. Yes, it is easy to change the code, but I thought I could accomplish it with cutter comp, which all of my operators understand the use of, hence the parameter question.

The above example code will achieve what you want. The value entered in the Offset Registry needs to be specified with the direction the tool is to offset. For example, to have the tool move further in the Y Minus Direction by 0.005, the registered value would have to be -0.005.

Regards,

Bill

 

[angelw]

You might be able to get this to work by programming a path like a square-bottom U shape (the dashed line below), where the bottom of the U is at the depth you want and the two legs are equidistant from the centerline of the keyway by the radius of the cutter (the red thing) plus 0.001 or whatever is the shortest move your control will allow.

That strategy will result in a Tool Compensation Interference alarm being raised if the required 0.005 offset is used.

Regards,

Bill

 

[PROBE]

Sorry for the terrible title, I wasn't sure how to explain it in a few words.

So I have a part that has a woodruff key cut into it, and I wanted to use cutter comp to adjust the depth. The tool is a woodruff keycutter, and I am plunging straight into the shaft in the Y direction.

I thought this was possible but the machine doesn't move as expected and I didn't see a relavent parameter.

Here is my code:

G0G55X1.38Y-.85S300M3
G43H5Z.1M8
G1Z-.4365F50
G1G41D5Y-0.506F1.5 (I want this to go further with a cutter comp adjustment)
G4X1
G40G1Y-.85F20.
G0Z5.M9


So If i put in a -.005 value in for cutter comp, it will move over .005" in X over the length of the move. Since the next movement is straight back out in Y, I expected it to not move sideways but instead go further in Y only.

I tried removing the dwell and having the next block be a Y move but it did not work.

Is this possible? Or am I stuck doing it other ways (such as modifying code, or using macro variables in my program)

Have a look on my post here https://www.practicalmachinist.com/forum/threads/max-vmc-backlashes.399467/#post-3885939 regarding the impact of the backlash on the uncontrolled move of the axis perpendicular to the axis of the movement.

Stefan
Cogito Ergo Sum

 

[SeymourDumore]

It sounds like you need a short segment of contour at the bottom of the keyway where the segment is parallel to the shaft. Otherwise, there's nothing for the cutter to compensate off of. You might be able to get this to work by programming a path like a square-bottom U shape (the dashed line below), where the bottom of the U is at the depth you want and the two legs are equidistant from the centerline of the keyway by the radius of the cutter (the red thing) plus 0.001 or whatever is the shortest move your control will allow. If I misunderstood what you are trying to do, I apologize.

View attachment 405720

Yupp, that would have been my suggestion.
Some controls behave differently, though sometimes it's just a parameter change.
The Haas ( will check in a minute ) should do it without a move.
I KNOW that a Brother HS3100 will do it without a move. Hell, that control will comp even without an actual programmed move.
On a Fanuc though, if the plunge and retract didn't work, I would have tried the following:

G0G55X1.38Y-.85S300M3
G43H5Z.1M8
G1Z-.4365F50
G1G41D5Y-0.506F1.5 (I want this to go further with a cutter comp adjustment)
G01 X1.379
G40G1Y-.85F20.
G0Z5.M9