[jay_dizzle]

its got a Fanuc control, but maybe someone here can help?

My Boss recently purchased a 2008 Okuma VTM-120Yb machining center with a Fanuc 18i-MB control. im self taught and have been working in the cnc game for the better part of 20 years but this one is giving me a headache.
ive got the machine up and moving around a bit, made a few cuts via MDI and all seems ok with the machine. but ive got some questions.

1) establishing work locations and tool lengths? i made a "probe" to use for touching off the work, for simplicity sake i left the tool length offset for the probe as zero. i touch the top of the work with said probe and establish it as zero in G54. x and y are zero for now.
the problem is, when i go to touch off my next tool. i bring the tool into contact with the work, and set the length based on the absolute display, and then send the tool "home". the issue is, when i send the tool back to ZO, it goes right past zero to about -1/2"

2) home positions (G27, G28, G30) what are these actually used for? when i try to use G27 the machine just goes to X0 Y0 and alarms out. G28 appears to be tool change position. and G30 is "home". these books say i dont need to send this machine home before operation so not too sure about the use of these

its also worth mentioning that when i touch off any work or tools, the values im having to input or "measure" are in the -20ish inches, which doesnt seem correct. any help would be very much appreciated as the machine came with almost zero for literature.

3) the machine has a tool setting arm, but i havent been able to find ANYTHING in relation to how to use it. so a shove in the right direction would be helpful with regards to that as well.

[elephantcnc]

Hello, dear friend. Maybe this can help you:
Okuma VTM-120Yb (Fanuc 18i-MB) 5-Axis Quick Guide
1. Work Offsets & Tool Lengths
Probe Setup: Touch workpiece with probe (H=0), set G54 Z0.

Tool Offsets: After touching tools, enter Absolute Z-value in the offset table.

Critical: Always use G43 H__ (e.g., G43 H1 for T1) to activate tool length compensation.

2. Home Positions
G28 = Safe retract (tool change position).

G30 = Secondary home (optional).

G27 = Rarely used (checks if at home, often alarms).

No homing required on power-up (absolute encoders).

3. Tool Setting Arm
Manually touch tool to arm, press "MEASURE" in offset page.

If automatic, check for G37 or custom macro (may need Okuma support).

4. Large Negative Offsets?
Normal (measured from spindle face). Ensure cuts are accurate—no issue if values are consistent.
Quick Fix for Overshooting Z0:
T1 M6
G43 H1 ; ? MUST INCLUDE!
G0 G54 X0 Y0 Z0
Next Steps: Test with simple moves, verify G43, and check tool presetter macros. Let me know if you need more details!
https://www.elephant-cnc.com/

[metalmayhem]

for fanuc try g91g28 z0 . Just be sure your programs have a g90 after you do a tool change (g90g54......)

[jay_dizzle]

Hello, dear friend. Maybe this can help you:
Okuma VTM-120Yb (Fanuc 18i-MB) 5-Axis Quick Guide
1. Work Offsets & Tool Lengths
Probe Setup: Touch workpiece with probe (H=0), set G54 Z0.

Tool Offsets: After touching tools, enter Absolute Z-value in the offset table.

Critical: Always use G43 H__ (e.g., G43 H1 for T1) to activate tool length compensation.


my tool offset is set to Z0 for my "probe" - when i touch it to the work, i then press "Z0-measure" - G54 ZM changes to -23.691

i then call G43 H1 and the absolute value for Z changes to -12.6559 this doesnt seem correct...


2. Home Positions
G28 = Safe retract (tool change position).

G30 = Secondary home (optional).

G27 = Rarely used (checks if at home, often alarms).

No homing required on power-up (absolute encoders).


thank you for confirming, i suspected this based on the age of the machine


3. Tool Setting Arm
Manually touch tool to arm, press "MEASURE" in offset page.

If automatic, check for G37 or custom macro (may need Okuma support).


discovered the tool touch arm to be broken today, technician is on his way to repair and calibrate


4. Large Negative Offsets?
Normal (measured from spindle face). Ensure cuts are accurate—no issue if values are consistent.
Quick Fix for Overshooting Z0:
T1 M6
G43 H1 ; ? MUST INCLUDE!
G0 G54 X0 Y0 Z0
Next Steps: Test with simple moves, verify G43, and check tool presetter macros. Let me know if you need more details!
https://www.elephant-cnc.com/


i include G43 in all of my tool length calls, however, how do you call tool geometry in turning mode?

also, can you tell me how to break up my "quotes" so that i can reply in a more organized fashion