CNC Services Northwest

Method 4: Use no reference tool, use length offsets to locate part

This method is comparable to what is done on some other CNC controls, which do not have a separate procedure for setting the Z axis part zero.

It is a reasonable method if you would have to measure every tool anyway (because they did not remain in their tool holders).

Pros:

Don't need a Reference Tool
Don't need to set Z reference before measuring tools
Don't need to set Z axis part zero

Cons:

Must measure every tool before every job
Can't compensate for variation in stock thickness
If you move the knee, you may have to remeasure all the tools again

Preparation (one-time)

Send the Z axis to home (TOOL CHECK)
Go to the offset library (F1/Setup, F2/Tool, F1/Offsets)
Press F1 for Z Reference
Press F10 to set Z Reference at Z home
Go to part setup (F1/Setup, F1/Part)
Select the Z axis (F1/Next Axis twice)
Press F10 to set the Z axis part zero at Z home

Operation (for each job)

Load all tools for the job into their tool holders
Load the stock in the vise or fixture
Go to the offset library
Load each tool, jog to the stock surface, and press F2 to measure
Press F10 to save the measured length offsets
Go to part setup
Set the X and Y part position, but not Z.

If you have to replace one tool

Go to the offset library.
Load the new tool and jog it to an uncut area of the stock surface.
Highlight the tool number and press F2 to measure.
Press F10 to save the measured offset.

If there is no uncut area available, you will have to use some ingenuity. If the new tool is approximately the same length as the original one, and there is some room to move it in the tool holder, you might try the following:

Insert the tool holder in the spindle, but leave the tool out for now.
Press F3 for the MDI prompt.
Jog over a cut area whose Z depth you know (e.g. a pocket cut to 0.5" depth), and which is large enough to set a 123 block on or in.
Enter a Z move to that position, plus the height of the 123 block, with length compensation for the tool in question.
E.g. to move tool 4 to a three inch block sitting on a half inch depth:
G43 H4 G1 F10 Z2.5
Slide the tool into the holder. Place the 123 block under it, allowing the tool to rest on the 123 block. Tighten the tool holder.

This ensures that the replacement tool is the same length as the original. It does not need to be measured.

Using a TT-1 tool detector

If you want to use a TT-1 tool detector with this method, you should set the following Machine Parameter values:

Parameter 71 = Calibrated height of TT-1 (usually a little over 2")
Parameter 43 = 1 (to tell the Offset Library that it needs to subtract the value of Parameter 71 from each auto tool measurement)