C axis cutter comp in sub spindle

[Mark K Smith]

Looking for some confirmation that my post is correct.  Have a DMG MORI NLX2500 Lathe with live tooling.  First time I have attempted a program with face milling on the sub spindle and I noticed that for climb milling it is outputting G42 instead of the G41 I expected to see.  Spindle is running in reverse as I expected.  Is this normal based on how the control calculates cutter comp for the sub spindle?  Hopefully somebody has encountered this and can allay my concerns before I run this job.

[crazy^millman]

Has the post been setup correctly and tested for this on the machine?

[Mark K Smith]

That is the big question, now isn't it?  I do not know that answer as I was hired after the machine and post were put in service.  At a minimum I will find out when the job starts, but I was hopeful that someone with more experience than I had encountered this before.  I am pretty new with live tooling lathes and have not encountered this before.

 

[Zoober]

Generally, CRC is opposite on the Sub. So G42 climb would be correct.

But definitely test.

[Mark K Smith]

Thanks Zoober.  I will be sure to test, but now with more confidence that my post is working correctly.  I appreciate the feedback all.

 

[crazy^millman]

5 minutes ago, Zoober said:

Generally, CRC is opposite on the Sub. So G42 climb would be correct.

But definitely test.

Yes it is one of those things I need to be in front of a machine doing and seeing to say I have a good answer. Every machine is different so all you can do is give a try being as safe as possible and see what happens.

[David Colin]

It s the same here on our Integrex. I wondered why and understood that X,Y an Z axis direction are the same for main/sub spindle but you are milling from opposite Z axis. You should also notice same behaviour with G2/G3.  

[Mark K Smith]

That's kinda what I suspected.  Seems for computational purposes the control must be always looking at things oriented "towards" the main spindle even with sub spindle work.

 

[Zoober]

2 hours ago, David Colin said:

It s the same here on our Integrex. I wondered why and understood that X,Y an Z axis direction are the same for main/sub spindle but you are milling from opposite Z axis. You should also notice same behaviour with G2/G3.  

That is why. As long as the Z motion is not mirrored.

Some machines, a Z- move is deeper into the chuck, Regardless of main or sub spindle.

This configuration swaps G2/G3 and G41/G42 from spindle to spindle:

Main                                                              Sub

Z- >>>>>>>Z+                                           Z- >>>>>>>Z+

 

This does not:

Main                                                              Sub

Z- >>>>>>>Z+                                           Z+ >>>>>>>Z-

 

Now, you can imagine my day. Creating and proving posts for 3 turret, twin spindle, 13 axis, 3 channel machines. Some Siemens, some Fanuc.

Throw in G18/G19 plane swapping for cylindrical and polar interpolation, depending on spindle/turret combination.

 

 

[Mark K Smith]

Learned the whole "why won't cylindrical interpolation work" thing on this machine as well.  It's a Y axis one also.  Seems it will drive G2/G3 just fine if you accidentally leave g18 vs using g17 but Cutter comp won't actually make any adjustments from zero.  I have enough headaches.  Sounds like you have your hands even more full.  haha    Thanks again for the confirmation of what I thought was the likely reason.

 

[crazy^millman]

16 hours ago, Zoober said:

That is why. As long as the Z motion is not mirrored.

Some machines, a Z- move is deeper into the chuck, Regardless of main or sub spindle.

This configuration swaps G2/G3 and G41/G42 from spindle to spindle:

Main                                                              Sub

Z- >>>>>>>Z+                                           Z- >>>>>>>Z+

 

This does not:

Main                                                              Sub

Z- >>>>>>>Z+                                           Z+ >>>>>>>Z-

 

Now, you can imagine my day. Creating and proving posts for 3 turret, twin spindle, 13 axis, 3 channel machines. Some Siemens, some Fanuc.

Throw in G18/G19 plane swapping for cylindrical and polar interpolation, depending on spindle/turret combination.

 

 

That was my point and when the upper and lower swap on top of it then you really get a head ache.

[Zoober]

2 hours ago, Mark K Smith said:

Learned the whole "why won't cylindrical interpolation work" thing on this machine as well.  It's a Y axis one also.  Seems it will drive G2/G3 just fine if you accidentally leave g18 vs using g17 but Cutter comp won't actually make any adjustments from zero.  I have enough headaches.  Sounds like you have your hands even more full.  haha    Thanks again for the confirmation of what I thought was the likely reason.

 

The sad part of all of this, is we had to create test coupons to verify planes, comp, and motion for a given combination.

Star (the Swiss machines we have) does not even know what the combinations are.

Their response to my inquiries ( the books don't go into that info for a given combo) was "we just program the way we think it should be, and if it is wrong, change it".

I explained that we are Post and Play, no at machine edits allowed, and his response was "nobody can do that on these machines". He is Star's best applications guy. That was also Partmaker's response.

We post directly to the machines. No matter how complex the operations. Including pinch milling and turning with 2 turrets, while pulling in Z sync and spindle/C sync with the sub spindle.

Needless to say, Autodesk (Partmaker) does not see our posts. It is our competitive advantage.

[crazy^millman]

2 minutes ago, Zoober said:

The sad part of all of this, is we had to create test coupons to verify planes, comp, and motion for a given combination.

Star (the Swiss machines we have) does not even know what the combinations are.

Their response to my inquiries ( the books don't go into that info for a given combo) was "we just program the way we think it should be, and if it is wrong, change it".

I explained that we are Post and Play, no at machine edits allowed, and his response was "nobody can do that on these machines". He is Star's best applications guy. That was also Partmaker's response.

We post directly to the machines. No matter how complex the operations. Including pinch milling and turning with 2 turrets, while pulling in Z sync and spindle/C sync with the sub spindle.

Needless to say, Autodesk (Partmaker) does not see our posts. It is our competitive advantage.

Yes sir.............................................................................................................

Thought you would agree. Thanks for reading what all I can't really say.