Strange tool length offset issue

[tcom-frazzled]

I just finished installing and setting up a renishaw nc3 on my cnc router. Since the machine doesn't have an ATC, I set it up so that Txx calls macro 9000 for a tool change. In the macro, I have the machine go to a predetermined manual tool change location, wait for the manual change, then on cycle start it executes the tool measurement macro., sets the active tool with a m6 T#149, and returns to the calling program.
The issue I'm having is that after returning to the program, z moves are not going to the commanded height, almost like it is applying the offset twice. I can watch the program zipping by and the commanded z height is not being followed. Oddly, if I jump out with a reset and go to the MDI, commanded Z heights are fine.
Anyone have a thought on what might be going on here? After tool changes, the code calls a g43 h to apply the offset.

[dcoupar]

I'm guessing this must be some super-secret proprietary macro, or you probably would've posted it here so maybe someone could figure out what it's doing.

[txcncman]

Would need to see the code.

[mick.w]

is it possible the probe is resetting your tool #'s, we had a similar problem and we simply recall our tool #'s using goto function

mick

[tcom-frazzled]

Nothing secret about the quick toolchange macro, I'm just not in front of the machine right now to grab the code to post it.

The thing that is really confusing me is that the running program is calling z moves that specify negative coordinates, like z-0.0125, but the position in the current workpiece coordinate system where it ends up is almost an inch higher. If I reset while it is cutting in air and go directly to the MDI, I can issue a g01 z0.125 f20 and it goes to the appropriate position without issuing any other commands.

I've checked the tool offsets and the macro programs them correctly. When it goes back to the program, the correct tool number is indicated, the correct H and D values are specified, and G43 is active. I'll post code this evening.

[txcncman]

Is it stuck in G91 Mode?

[tcom-frazzled]

So, they say a picture is worth a thousand words. Here is a capture of the screen showing the just executed retract G00 Z0.4 that had been executed and look at the Z position on the screen. You can also see from this screen cap what modal G codes are active. Maybe this is just a lack of understanding on my part about how tool length offsets appear while the machine is running, because if you look at the two attached screenshots, you'll see that it is exactly the tool length above the workpiece while running.

[txcncman]

What is in the G54 offset for Z?

[tcom-frazzled]

Z offset is -4.2390. I used the tool change macro to install tool 1, then used the MDI to execute a G43 H1 to set the offset active. After which I touched off the top surface of the material and used the indicated Z position to input the offset.

Maybe it is just my understanding of how G43 works that is the problem. When jumping between G49 and G43H1, I would expect the Z position to remain the same on the DRO and just the tool length offset to be applied and to tool to move in the positive direction by the distance of the length value. What I'm seeing is that when I jump between G49 and G43 modes, the DRO value changes.

[txcncman]

Oh. No. I think I am understanding now. What I am not seeing is if you confirmed the DRO tool position is the actual tool position in the machine. If the DRO is reading 1.4126 positive above the set Z work zero, is that the actual distance from tool tip to the set Z work zero in the machine?

[tcom-frazzled]

Yep, that is the actual position of the tool above the workpiece when this is running.

[txcncman]

Ok. Then yeah. You were misunderstanding the order of operations for the DRO to get where it is. Sorry for the misunderstanding and bad communication. If the DRO says the tool tip is at 1.4126" above the Z work zero and it physically is that distance, then all is well.