Fanuc Subspindle positioning questions

Finally getting to the sub spindle on a Romi E320 with a fanuc 18i control. I noticed that the subspindle positioning is a negative number when activating the part transfer codes, I imagine that is because when I am positioning it within a program it is within the control of the main spindle? I am thinking about using a g55 for the sub and using offsets 21-32 for the sub tool offsets.. (turret has 12 positions) so tool one would be 0101 for main and 0121 for sub? is that a good way to go? one of the main questions is when in the g55 side of things working on the sub does the negative tool movement in z work the same, so negative is toward the chuck? This may all be wrong, and I am open to any easier ways to go about this, this lathe does have sync on the spindles, and I am just really trying to get my head around the offsets on sub lathes as I am very new to them.. The cam program I am working on can be set up to do just about anything, what is the best way to go? thoughts?
thank you

I add 30 to my offset number(T0131) since each of my turrets has 24 possible tool positions but whatever makes sense for you will work. Use G55 for sub and Z- will always be to your left so to move towards the sub chuck will be a positive number.

All of the sub werk on any of our lathes is all positive.

0121 is fine.


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Think Snow Eh!
Ox

Don't know how the Romi is set up, but on a Mori every coordinate follows the very same common direction for all operations regardless of which chuck you're working on.
IOW regardless of what you're doing, X+/-, Y+/-, Z +/-, C +/- and spindle Fw/Rev is common.
X+ is away from center line, X- is towards the centerline.
Y+ is above centerline, Y- is below centerline.
Z- is towards main spindle, Z+ is away from main spindle.
Spindle Forward is CW on main spindle, CCW on subspindle.
Tools have inserts pointing down on Main side, pointing up on sub.
Insert tip directions also follow the common direction, so a typical OD turning tool on the Main side is Dir 3, while it's 4 on the sub.
Similarly tool nose comp follow the common rule, so a typical G42 on the Main is G41 on the sub.

So If your machine is set up the same way, then negative Z is always towards the main, so your programs on the Subspindle will be positive Z movements.
For example if I have a program written for the main, but now just want to put it on the Sub, I just mirror the code in NcPlot, change tool numbers and comp directions.

As for the subspindle part transfer, that's also in the common coord. system, so negative Z is towards the Main.