Fanuc 21-iTb control g12.1 "DANCE"

[Cnczack]

So this isnt specific to the control but every program I write (for a c axis lathe) program to do any sort of milling with g12.1 active before it starts it does this little dance i call it. it starts off away from the center of the part then begins to rotate the chuck (c axis) while moving the x axis, it goes towards the center of the spindle then back out before milling. What even is that and why would that happen? also in relation to program i do not program this, its not in the code but it is as soon as it hits the g12.1

on a related not we have a fanuc 21-iTB control, doosan vtl with c axis. while it does this dance it will spin so hard and fast it alarms out the spindle servo. ive tried messing with param. 5462 to slow it doesn but doesnt seem to help. any suggestions or ideas of this would be great.

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[servtech]

So this isnt specific to the control but every program I write (for a c axis lathe) program to do any sort of milling with g12.1 active before it starts it does this little dance i call it. it starts off away from the center of the part then begins to rotate the chuck (c axis) while moving the x axis, it goes towards the center of the spindle then back out before milling. What even is that and why would that happen? also in relation to program i do not program this, its not in the code but it is as soon as it hits the g12.1

on a related not we have a fanuc 21-iTB control, doosan vtl with c axis. while it does this dance it will spin so hard and fast it alarms out the spindle servo. ive tried messing with param. 5462 to slow it doesn but doesnt seem to help. any suggestions or ideas of this would be great.

Have you tried calling and referencing C axis first?
It may be switching from spindle rpm to c axis mode during the little "dance".

Ie.

M17 or whatever call is on your machine
G01 C0 F1000
Tool call and live took speed
Milling program.

[Cnczack]

Have you tried calling and referencing C axis first?
It may be switching from spindle rpm to c axis mode during the little "dance".

Ie.

M17 or whatever call is on your machine
G01 C0 F1000
Tool call and live took speed
Milling program.

yes, it all of my programs I have a C0 before starting then it his the G12.1 then starts its weird little move

[zavateandu]

can you post a short movie with the spindle move and the position of the C axis on display?

[servtech]

yes, it all of my programs I have a C0 before starting then it his the G12.1 then starts its weird little move

I suspect then it's syncing to the program polar coordinates prior to cutting. I've seen plenty of air moves on machines over the years, lathe-mills and machining centers. The start point has to be found because it's all important.

[Dale123]

Try Parameter 5450 Bit 1 to 1 . It stops the C Axis jump to C/Line

[Cnczack]

I suspect then it's syncing to the program polar coordinates prior to cutting. I've seen plenty of air moves on machines over the years, lathe-mills and machining centers. The start point has to be found because it's all important.

thats what i was assuming it did but still i would think it could line up away from the part