Fanuc G36/G37 wrong wear offset value.

[EKrol]

Hello everyone,

Machine: Doosan SMX2600S
Control: Fanuc 31i-b

I use a calibrated tool (30mm ball) to set thermal parameters before using the toolsetter to set tools.
The values of the calibrated tool are known so i measure the tool with the toolsetter and adjust parameters so the wear value becomes 0.
Works great. All tools are always <0.01mm from toolsetter.

The only weird thing is that i always get a 0.07mm wear value difference between using the toolsetter manual en via G36/G37.
In my program i correct for this value so thats not a problem but i dont get why its doing that.
Speed is always 30mm/min for measuring. Its 0.07mm in X and in Z direction.

Anyone know why?

Gr

 

[sinha]

Try manipulating parameters 6241 and 6251/6252.

Even though the delay in sensing the deflection (causing an overshoot) and transmitting the signal is pretty small (typically 2 milliseconds), it does affect accuracy. Therefore, a low feedrate is preferred during measurement. The measurement feedrate is stored in parameter 6241 which automatically applies when the tool is within a small distance of the target surface. This distance is stored in parameter 6251 for X axis and 6252 for Z axis.

 

[EKrol]

Try manipulating parameters 6241 and 6251/6252.

Even though the delay in sensing the deflection (causing an overshoot) and transmitting the signal is pretty small (typically 2 milliseconds), it does affect accuracy. Therefore, a low feedrate is preferred during measurement. The measurement feedrate is stored in parameter 6241 which automatically applies when the tool is within a small distance of the target surface. This distance is stored in parameter 6251 for X axis and 6252 for Z axis.

tnx for the reply.
But if a change the feedrate it also changes the feedrate for the manual use of the toolsetter. So that wont change it. Just tested it at 10mm/min and get the same error.
Its almost like there is a setting to compensate G36/G37. The repeatability of the toolsetter is phenomenal BTW.

Gr

 

[sinha]

The 6241 feedrate is internal to G36. Won't affect other feedrates. Make is very low. Also, check the other two parameters. Should be at least 1 mm

 

[EKrol]

The 6241 feedrate is internal to G36. Won't affect other feedrates. Make is very low. Also, check the other two parameters. Should be at least 1 mm

Yep you are right. Sorry. But the error is thesame on F30 and F10.

current parameters:
6241 30.0000
6251 5.000
6252 10.000
6253 0.000
6254 5.000
6255 10.000
6256 0.000

Gr

 

[sinha]

Reduce 6241

 

[sinha]

G36 is currently using F30, when the target surface is close. F10 is not being used for actual measurement.

 

[EKrol]

Yep you are right. Sorry. But the error is thesame on F30 and F10.

Gr

G36 is currently using F30, when the target surface is close. F10 is not being used for actual measurement.

Did set 6241 to 5mm/min. The error was now 0.036mm.

 

[EKrol]

G36 is currently using F30, when the target surface is close. F10 is not being used for actual measurement.

i did change 6241 to 10 when i did the F10 test

 

[EKrol]

The thing i don't get why it's different from using the toolsetter manual and automatic. The error from the delay of the sensor would be the same on the same feedrate i guess?

 

[sinha]

I don't have answer for everything.
May try reducing 6241 to 2, for more accuracy. Watch the feedrate display for confirmation.
Also, reduce the proximity distances; otherwise too much time would be wasted.

 

[sinha]

There is more to G36 than I have explained. If this much information does not solve the problem, I will look at it again.

 

[sinha]

You may also try G31. That will involve some coding, though. Use 2-touch method.

 

[EKrol]

You may also try G31. That will involve some coding, though. Use 2-touch method.

I will try to make a program using G31 on Monday. Tnx for the information

 

[EKrol]

You may also try G31. That will involve some coding, though. Use 2-touch method.

Did a quick test with G31. The problem is if the tool touch the toolsetter it just stops. No message. Just stay still with green light on.

 

[sinha]

Are you not able to retract it?

 

[EKrol]

Are you not able to retract it?

Its not going to the next line. G31 U1; G01 U-1; its stuck at G31. I can retract it by hand.

 

[rjwalker1973]

G31 is signal interrupt it will stop immediately if the stylus makes contact because it is used for safe positioning of your probe to prevent crashes. Sounds like it is doing the same with the tool. Not sure why the manual and automatic is different unless the response time from the tool setter is different between the two cycles. Be careful messing with federates, especially if it is your probe cycles themselves. I recalibrate my tool setter and probe anytime I have to change federates.

 

[sinha]

It will be more clear if complete program is posted.

 

[EKrol]

It will be more clear if complete program is posted.

i will.