G71 not retracting straight back along Z

[CPMFG]

I am using a G71 roughing cycle with a boring bar. After making the rough pass, I would like it to retract along Z without any X movement. The Fanuc manuals don't mention anything about this behavior and I can't find a parameter related to it. Control is an Oi-TF Plus
(Error: The note in the picture is wrong. It's retracting to the start of the pass it just finished, not "next pass")

 

[sinha]

What you want is the standard behavior.
Probably, model F-PLUS has modified the toolpath.
There may not be a parameter to change this behavior.
You may try searching for G71 in the parameter manual, and analyse all occurrences.

But, what is the harm in the new toolpath?

 

[William Lynn]

Are you using G71 to profile or are you just boring straight in Z? If straight, try G90 if your controller uses it.

 

[sinha]

Are you using G71 to profile or are you just boring straight in Z? If straight, try G90 if your controller uses it.

It is a good suggestion, though the cycle time would be more than that with G71.

G90 is standard.
But, they might have modified G90 toolpath also. One needs to check.

 

[rjwalker1973]

I am using a G71 roughing cycle with a boring bar. After making the rough pass, I would like it to retract along Z without any X movement. The Fanuc manuals don't mention anything about this behavior and I can't find a parameter related to it. Control is an Oi-TF Plus
(Error: The note in the picture is wrong. It's retracting to the start of the pass it just finished, not "next pass")
View attachment 399979

Can you post the code? It should go straight back unless something has been modified like Sinha said.

 

[alphonso]

On my 0TC and 21iTB the move back to start point is a Z move. Maybe some parameter sets the behavior?

 

[CPMFG]

Can you post the code? It should go straight back unless something has been modified like Sinha said.

G0G28U0W0
G40G80G99
G97S2500M03
T0606
M8
G00X1.15Z0.1
G96S400
G71U600R200
G71P406Q413F.012U-.01W0.003
N406G00X2.21
G01Z0
Z-3.01
X2.18
G03X1.2054Z-4.475I-2.446
G01X1.18
N413X1.15
G00Z.5
G97S1500M09
G00G28U0W0
M34(CHIP CONVEYOR OFF)
M01

 

[CPMFG]

But, what is the harm in the new toolpath?

The insert makes contact with the material on the way out.

 

[CPMFG]

Someone I know who has the same machine had the same issue. They had to change a parameter, so now just waiting to hear back once the service tech gets back with me. Will update when I can.

 

[angelw]

G0G28U0W0
G40G80G99
G97S2500M03
T0606
M8
G00X1.15Z0.1
G96S400
G71U600R200
G71P406Q413F.012U-.01W0.003
N406G00X2.21
G01Z0
G01 Z-3.01
X2.18
G03X1.2054Z-4.475I-2.446
G01X1.18
N413 G01 X1.15
G00Z.5
G97S1500M09
G00G28U0W0
M34(CHIP CONVEYOR OFF)
M01

I would be surprised if it made any difference to your issue, but the blocks in Red above are not required.

 

[DouglasJRizzo]

One glitch in G71 is that if you're doing ID boring, the last X axis line has to be the same as the starting X axis.
So if you're starting with a 1.25" bore, you have to end with a 1.25" bore

Example:

G0G54G99T0505
X6. Z4.M8
G97S1250M3
X1.25Z.25
G71U.1
G71P1Q2U-.01W.002F.008
N1G0X2.
G1Z-1.
N2X1.25
G0Z4.M9
ETC

 

[CPMFG]

One glitch in G71 is that if you're doing ID boring, the last X axis line has to be the same as the starting X axis.
So if you're starting with a 1.25" bore, you have to end with a 1.25" bore

Example:

G0G54G99T0505
X6. Z4.M8
G97S1250M3
X1.25Z.25
G71U.1
G71P1Q2U-.01W.002F.008
N1G0X2.
G1Z-1.
N2X1.25
G0Z4.M9
ETC

Doesn't mine start and end at X1.15?

 

[DouglasJRizzo]

Doesn't mine start and end at X1.15?

Yes, it does. However, you do have an "R" word on your DOC line. That "might" be interfering as it's an ID cycle.

 

[sinha]

The insert makes contact with the material on the way out.

It will make contact only at the start point. If you provide some Z clearance, it will lie outside the workpiece.

 

[CPMFG]

It will make contact only at the start point. If you provide some Z clearance, it will lie outside the workpiece.

Theoretically yes. In practicality no. It retracts to Z.1 There is plenty of tool deflection to allow for unwanted contact.
Regardless, I need this retract behavior changed.

 

[rjwalker1973]

It will make contact only at the start point. If you provide some Z clearance, it will lie outside the workpiece.

I agree. could also go to type 2 roughing. Don't think it will matter much, but the type 1 can be a bit wonky on the retract.

 

[sinha]

One glitch in G71 is that if you're doing ID boring, the last X axis line has to be the same as the starting X axis.

Theoretically, it is not required. The last point on the profile automatically gets radially extended up to the cycle-start X. At least, this happens in case of OD machining which results in some air-cutting. Since air-cutting is not desirable, X clearance may not be given.
Finishing allowances not shown in the figure below.
.

I am not sure about this behavior in ID machining.
Please check it once again and let me know. I will modify my write-up accordingly.
I expect this in ID machining:

 

[BT Fabrication]

G0G28U0W0
G40G80G99
G97S2500M03
T0606
M8
G00X1.15Z0.1
G96S400
G71U600R200
G71P406Q413F.012U-.01W0.003
N406G00X2.21
G01Z0
Z-3.01
X2.18
G03X1.2054Z-4.475I-2.446
G01X1.18
N413X1.15
G00Z.5
G97S1500M09
G00G28U0W0
M34(CHIP CONVEYOR OFF)
M01

the N413 is telling to end the program but you are telling it to move X right with it into the part.

 

[DouglasJRizzo]

Theoretically, it is not required. The last point on the profile automatically gets radially extended up to the cycle-start X. At least, this happens in case of OD machining which results in some air-cutting. Since air-cutting is not desirable, X clearance may not be given.
Finishing allowances not shown in the figure below.
View attachment 400054.
I am not sure about this behavior in ID machining.
Please check it once again and let me know. I will modify my write-up accordingly.

In ID machining, if you do not end at the X start, per my example, the tool will strike the work piece on retract in Z. This has occurred on every Fanuc model I've tried it on. Fanuc System 10, 11, 12, 0, 6, 32.

 

[sinha]

It is not clear to me as to where it will strike the workpiece. From the last point on the profile, it should come back to the cycle-start point, showing dogleg effect, on model C and earlier models. Model D has some difference (it has radial retraction, followed by axial retraction).

In any case, since radial clearance is not required, this does not come into the picture.