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  1. #1

    Unexpected Move

    On a 1993 Fadal VMC 4020 with CNC 88 control. Why is the Z axis moving when a tool length offset is specified e.g. M6 T1 H1? It does this with no other commands and with or without a fixture offset active. In fact, in MDI mode, if you simply type H1 - H21 it moves Z to the amount specified in the corresponding number of the tool offset table. Same problem when running a program, which will crash for sure as the X,Y is not always in the correct position for machining during a tool change. BTW the tool changer works fine and has none of the common problems.
    Second question which may or not be related. Why is the tool in the spindle always followed by a .25664? For example it will say TOOL 1.25664 IS IN THE SPINDLE. The offset table does not reflect this annoyance.

    Thanks in advance for any help with these issues!

  2. #2

    Re: Unexpected Move

    It's not common practice to call a tool offset in the same block as a tool change. Typically it is called in the first move in Z after a tool change. Orderly application of tool height offsets is important unless you're looking to inadvertently bury a tool into your work or work table.

    Here is a good example of bringing in a tool height offset and getting any tool up and running safely.

    M6T1 (ANY DRILL OR TOOL)
    G17G20G40G49G54G80G90G98

    G0 X1.0 Y-0.5
    G43 Z0.1 H1 S2500 M3 T2 (LEAVE OUT T2 (get ready tool) IF YOUR MACHINE HAS A CAROUSEL CHANGER AND NOT SWINGARM TYPE)
    M8
    G99 G81 Z-0.7 R0.1 F15.
    ETC.....................

    Do not cancel (G49) or start new tool offsets when the head is near the work.

    This is Fanuc based. Sorry if some of it doesn't apply to Fadal.

  3. #3
    Member
    Join Date
    Oct 2008
    Posts
    1509

    Re: Unexpected Move

    Question 1 - typically you need to supply a Z move with an Hx Length offset. This is like calling an XY position when changing work offsets.
    As the previous poster mentioned, leverage the Hx call with the new position of the desired Z position and it works out.

    Question 2 - Sounds like something corrupt. Have you performed a Zero / Clear memory? If the machine has been shut down for any length of time, the memory can become corrupt as well as the parameters. Clear Memory then walk thru setp.

    Richard


    Quote Originally Posted by magatechutah View Post
    On a 1993 Fadal VMC 4020 with CNC 88 control. Why is the Z axis moving when a tool length offset is specified e.g. M6 T1 H1? It does this with no other commands and with or without a fixture offset active. In fact, in MDI mode, if you simply type H1 - H21 it moves Z to the amount specified in the corresponding number of the tool offset table. Same problem when running a program, which will crash for sure as the X,Y is not always in the correct position for machining during a tool change. BTW the tool changer works fine and has none of the common problems.
    Second question which may or not be related. Why is the tool in the spindle always followed by a .25664? For example it will say TOOL 1.25664 IS IN THE SPINDLE. The offset table does not reflect this annoyance.

    Thanks in advance for any help with these issues!

  4. #4

    Re: Unexpected Move

    Performing the Memory Clear fixed the TOOL 1.25664 IS IN SPINDLE...its now TOOL 1 IS IN SPINDLE. We will see if the tool length offset is fixed tomorrow. It certainly could have been caused by a memory full of junk. If not, we'll try your suggestions. Thanks Gentle Giant and Richard!

  5. #5

    Join Date
    Feb 2020
    Posts
    12

    Re: Unexpected Move

    Quote Originally Posted by magatechutah View Post
    Performing the Memory Clear fixed the TOOL 1.25664 IS IN SPINDLE...its now TOOL 1 IS IN SPINDLE. We will see if the tool length offset is fixed tomorrow. It certainly could have been caused by a memory full of junk. If not, we'll try your suggestions. Thanks Gentle Giant and Richard!
    Sounds like an error in your post processor, to me. What are you using for cam and what post?

    Sent from my SM-G981V using Tapatalk

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