Fanuc 3TF thread cutting stops at second line "buf"

[Han-F2a]

Hi Guys,

I have a Mondiale Gallic 420 cnc lathe with Fanuc 3TF that I use for making model engine 2 stroke parts. It lost all parameters, and I re-entered them from my list. It works fine again, but thread cutting doesn't work anymore. When I go through the 2 G76 lines single block, it positions the tool nicely, locks the rpm at the bottom of the screen , and even gives an x and z value in "distance to go". Then the word "buf" appears at the bottom of the screen and does not continue.the spindle keeps on running and no alarm appears. It seems as if it is waiting for something.


Is there any diagnostics I can check?

Please help.

 

[Vancbiker]

I suspect the control is not seeing the signal from the spindle encoder. I do not have any documentation for the 3 series control to point you to any diagnostics or connections to check though.

 

[guest]

...When I go through the 2 G76 lines single block, it positions the tool nicely, locks the rpm at the bottom of the screen , and even gives an x and z value in "distance to go". Then the word "buf" appears at the bottom of the screen and does not continue.the spindle keeps on running and no alarm appears. It seems as if it is waiting for something.

Another press of cycle start?

What happens when you take it out of single block and just let it run?

Single block can be kind of funky in canned cycles- in some situations it can take several presses of the cycle start button to make it take off.

 

[yardbird]

You've threaded on this machine before using the two line cycle?

Brent

 

[Han-F2a]

Hi , Thanks for your advice .
i looked up diagnose 027 bit 0 should be the spindle signal one per revolon arrival : 1 = arriving, 0= not arriving. at my machine it is 0. However:
bit 1 and 2 are arrival of X and Z axis signal , one per rev, and they are both 1 , even when put the machine on and without turning the x an Z axis. It appears that these bits for X and z axis are always 1.
Also, I get rpm reading on the screen, this would not be the case if the signal from the encoder is not arriving?
So, i am confused.

 

[Han-F2a]

Thanks for your help! extra press of cycle start won't help. If I leave out Single block, it won't continue either.

 

[Han-F2a]

Thanks Brent for helping me. Yes I have done many threads before with the 2 line G code. The program was still in the machine , so I am sure the figures are ok.

 

[Ox]

Must be a param for the threading encoder yet would be my guess.

RPM and this encoder should not be the same.


-----------------

Think Snow Eh!
Ox

 

[aj]

It works fine again, but thread cutting doesn't work anymore.

You said you lost all parameters. The 3T is pretty old. I'm pretty sure G76 was an option. Someone may have enabled it at some time in the past but when those parameters were lost and you re-keyed everything in from the factory sheets the 'option' wasn't re-enabled.

 

[Fancuku]

You should be threading with G92 anyway.

 

[Vancbiker]

If it were mine, I'd put my o'scope on pins 14 and 15 of connector M11. That is the one rev pulse of the spindle encoder.

If the option parameter for G76 was not on then he would get an alarm 10.

 

[aj]

If the option parameter for G76 was not on then he would get an alarm 10.

You are correct. I just tried MDI-ing(?) a G76 and got an alarm 10 on our 3T.

 

[Han-F2a]

Hi guys,

GOT IT SOLVED!!!! It was the encoder that was broken. It did not send the pulses. Bought a second hand and mounted it . Diagnostics 027 bit 0 was 1 right away. Now I can make crankshafts again!

Thank you all for your support!