Fanuc OM Work offset Help

I'm new at VMC. I am trying to set up tool offsets and the work offset(g54). I turn on the VMC jog each axis and home all axis. If there is any valves in the relative position display other than 0, i reset them to 0. I have a tool setter height gauge that I set on the table. I install a tool, and jog down till tool tips touches the z setter gauge. I install the number into the offset that I assigned to that tool with EOB Z and insert. Repeat for each tool. All z values are - values which make sense because z is below or - direction from the machine 0. Now on to setting the work offset. I can jog over and get the X and Y values right, but the z still is puzzling. I jog the z to the top of the work piece. relative position is -4.3265 or +3.4339 above the Z setter height for the tool that I am using (tool offset is -7.7604). I am think I am to put +3.4339 into the work offset z value. I go into MDI and enter with the correct tool number and H offset selected input a z0 command. the Z wants to move upwards which is an over travel error. I get all axis back to machine 0. set the work offset to -3.4339. Back to MDI. Input z0. Tool moves down to a position 3/4" off table or 3.4339 below the z tool setter height. (which makes sense because i set the work offset to -3.4339 I can cycle though all the tools and the Z0 will always be 3/4 off the table or 3.4339 below the tool setter height. So I assume that the tool offsets are correct, just the work offset isn't correct. Anyone can see what I am doing wrong. G54 and G43 are selected.

D,

Take a look at this post:
http://www.cnczone.com/forums/fanuc/...ml#post1762320
Superman (Post #9) talks about setting up the overall machine offsets. Post #5 is code from one of my machines and should give you some ideas about how to set up your code. I have cut sections out of the code to shorten it. What remains is the code relevant to tool changes.

Charles

Is there a reason that the tool setting height must be above the work the work offset height.

Quote:

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Originally Posted by dpaulson

Is there a reason that the tool setting height must be above the work the work offset height.

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Those are 2 different items, like apples & oranges

Work offset height is the distance from the spindle face ( or from the end of a referencing tool ) to the Z origin that you have programmed your part around
Tool length is the distance from the tool tip to the spindle face ( or to the end of the referencing tool ) if using G43 H#
Tool length is the distance from the spindle face ( or to the end of the referencing tool ) to the tool tip, if using G44 H#
( NOTE how these are worded, this gives you the correct sign to input with the distance )

Normally a tool setter is calibrated using a reference tool ( known length from the spindle ) when gauging, it should return a length distance that can be physically measured, ie from the gauge line on the taper ( very near to the spindle face ) to the tip of the tool


What values are you getting from your tool setter Vs ruler measurement ? are they nearly the same ??


Do not zero out the RELATIVE positions after homing, it is displaying the current position of the spindle / tool with respect to the active co-ord system ( normally G54 )
( you can zero the RELATIVE position when using manually, ( or setting up a job ), but homing again resets the values in respect of the G54 origin

If you want to understand the theory behind offset setting, pm me your email. I would send you some material.

Sinha

The tool offsets are based on the NEGATIVE difference from all your tools, starting from the LONGEST.

So here:
tool 1: length 7.5
tool 2: length 4.5
tool 3: length 6.5 (also axis probe)

You would set your offset of tools:
Tool 1: 0
Tool 2: -3.0
Tool 3: -1.0

Basically the distance that the Z axis has to "fill" when it changes tools. When you go from a 7.5" tool to a 6.5" tool, the Z will correct with the H offset of -1.00, and will correct accordingly. Ive broken a LOT of end mills when I first got my OM-B running, a 4x4 piece of wood is your friend when trying to set up tooling the first time.

Keep in mind also when setting your Z0 point on your work to have G43 and whatever tool number H offset active, so if its tool 20 (like I have mine), go to MDI and type G43, input, Shift, H, 20, input, Output start, the Z axis will move a little bit to offset from your currect Z offset to your Tool Offset, so beware. Then, touch off your part, set G54 or G92, and then let her rip.

I have gotten to a point that I can use the machine, so as I set up for different jobs, eventually it'll start to make sense.

Good progress!
The offset thing is so logical. One only needs to understand the theory behind it which is not a rocket science.

I have an OMD.

G43 H# moves the axis immediately to the preset value. Can be quite dangerous if at Machine 0

I'm tying to move the Z to a safe point before implementing G43 or cancelling it G49.

Any idea on what registers holds the current tool and the new tool length.

I want to move the Z to G53 + or - offset length then do the change length thing.

Remove current tool length

G53 Z????
G49

ATC Change tool

New tool length.

G53 Z????
G43 H#20 (#20 is my tool number)