Need Help!- 18i-TA zero return (home referencing)

[padobranac]

I have bought used machine ROMI G15SM, 2001. y. (lathe with sub-spindle - B axis)
Control is GE Fanuc 18i-TA

I have problems with home referencing, zero return.
Here is scan from operation manual that i got with machine.



When I started machine for the first time, I got alarm:
300 B AXIS NEED ZRN

I have done procedure from last picture, and just B axis went to zero.
The problem is that position of zero is wrong, it is in the middle of the stroke. It should be on right edge, so all movements are in negative direction.

So, after that, machine is 100% functional, everything works!!!
And if I turn off machine and than turn on, there is no alarm and I can not make home reference return. But machine is fully functional.

I have found some manuals in PDF for same machine but for "V 2.0 line".
Please check next picture.



Obviously, this should be for my machine, but I am not sure.
And now I am very confused, does it have absolute encoders or not?
There are no LED-s that indicates zero point accheved (like there is on my two VMC-s)
And I can not found any limit switches, neither physically on machine nor in electric diagram.

SECOND PROBLEM, but I think related to first.
Look at the next picture. Offsets wear/geometry are all cleared and work coordinate systems all set to 0.



I think that dimensions RELATIVE / ABSOLUTE / MACHINE should be exactly the same for each axis (is all compensations are off, and I think they are).

You can see that Z and C have some differences......

[moowod]

Absolute encoder is for X Z axis but not for B or C.

You need to make ZRN for B. If after pressing the HOME + B Jog(-) there is no move from axis so you can try in a G28 B0.

[padobranac]

Originally Posted by moowod Absolute encoder is for X Z axis but not for B or C. You need to make ZRN for B. If after pressing the HOME + B Jog(-) there is no move from axis so you can try in a G28 B0.

Are you sure? You say so just because of second picture (this is from manual for G15M which does not have B axis) or you have experience with ROMI?

If you are wright, why I was asked to do "B aris ZRN" just first time after transport, and never more?

I think G28 G91 B0 just goes to position 0, not to reference position switch (sensor).

[moowod]

No I don't have experience in ROMI but you can take a look on machine offset to compare value and absolute position.
In case you can check value between spindle and real b axis position.

[padobranac]

"machine offset"? If you mean tools offsets, they are all cleared (set to 0).

About the second problem, please check the next picture.
When I put this axis (B) in the zero position, arrow on the picture is 30 centimeters (about feet) far from another arrow which is on fixed, lower part of the axis.
Probably the original machine zero is when upper and lower arrows are collinear.
And obviously zero is out of position, in wrong place.

[xavierdemoura]

1) Move machine to the mark´s.
2) MDI Mode
3) OFFSET/SETTING 2x
4) Parameter Write Enable to 1
5) SYSTEM
6) PARAM
7) Press 1815 and NO.SRH Softkey
8) Bits #4 and #5 of B Axis need stay in 1
9) Turn Off and Turn On the machine again
10) Put Parameter Write Enable to 0

In reference to your manual, the X and Z axis are relatives, must need do the reference, the B and C axis are absolute, they has an battery to supply the power to don´t loose the position.

Best Regards,

Daniel

[padobranac]

Problems solved, thanks to everyone.

So, I figured that all linear axes (X, Z and B) DO HAVE absolute encoders. And for some reason B axis lost zero position, so I moved it to mark where machine zero is and I have done procedure with APC and APZ.

For second problem, problem was with "WORK SHIFT", I even didn't know that this screen exist, I was just watching to work offsets (G54 etc).