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  1. #1
    Join Date
    Mar 2006
    Posts
    26

    Boring bar backoff value problem

    I am training on a Mazak Nexus-250-II Quick Turn.

    I have a threaded (ID) part and need to adjust the threading, and boring tool,
    back off so the bars don't crash into the back side of the bore.

    I believe the backoff in the software is around .078" which limits the bar size
    for a .500-20 thread severely.

    Is this a parameter that can be changed easily?

    Thanks,

    Kap Pullen

  2. #2
    Join Date
    Mar 2008
    Posts
    638
    On our mazak nexus qt-100 it's in TPC (and parameter) U7
    Double check in your Parameters book to make sure yours is the same.

  3. #3
    Join Date
    Apr 2006
    Posts
    3206
    Funny ya mention that....I just had to reset mine today for a job...a 9/16-18 hole.

    '99 SQT250M

    U7 is the back-off value....I'm in inches, and the value is in integer units/ .0001

    Mine is set at 800 , which translates to .080"

    You should REALLY have the manual with all the values. Screwin' around with parameters can get real expensive real quick. Whoever you're training under should know what you're doing, in case you change something they don't know you've changed and .... things get real expensive on a later job.

    You should also have access to the parameter, operation, and programming manuals. I think they're horribly written, but you should still have 'em.

    ..Btw, you can also do MNP and do plain ole G-code for the boring bar if things are just too dicey. My boring bar was way too big, but only option, so I programmed it in G-code, and lowered the threading tools U7 parameter for clearance on it.

  4. #4
    Join Date
    Mar 2008
    Posts
    638
    I mentioned parameters in parenthesis but I first said TPC. If you do it in TPC it changes it only for that op. And if you don't like it just cancel TPC with -9999 and you're back to square one. No harm.
    What I like to do is make changes in TPC and then run graphics. Watch the tool path. It really does what you changed. If I'm not sure, sometimes I will change it a lot to make sure that it is moving and moving in the direction I expect.
    I agree with fizzissist that you should have the book. And that if you change it in Parameters that it could get expensive on a later job. Do it in TPC. Watch your tool path either way you do it! Very powerful tool.

  5. #5
    Join Date
    Feb 2007
    Posts
    198
    Guys - double check this.

    U7 is for Fusion
    TC38 is for Matrix.

    Same exact concept, just differing parameter address.

    -jim

  6. #6
    Join Date
    Mar 2008
    Posts
    638
    Quote Originally Posted by jimiscnc View Post
    Guys - double check this.

    U7 is for Fusion
    TC38 is for Matrix.

    Same exact concept, just differing parameter address.

    -jim
    Thanks for clarifying. Yeah, you're right. We have a fusion control and it's U7.

  7. #7
    Join Date
    Jan 2010
    Posts
    1
    Definitely TPC for this. Go to program edit, select your bar in or thread in sequence, hit the TPC soft key (menu), and it will list all your clearance dimensions. On the QT20HP I run, clearance in, out, face and back are all set to .080". I would start by changing clearance in to .020 (I've had to use even less before), just make sure your sequence show a highlighted "+" sign, that lets you know TPC is active in that sequence. Good luck, and proceed with caution!

  8. #8
    Join Date
    Aug 2010
    Posts
    18

    Re: Boring bar backoff value problem

    Hello guys,

    Anyone know which parameter to edit for approach and retract clearance before and after an ID thread for T2 Mazatrol? The attached video depicts the problem with the stock moved back away from the cut area to show when it would crash.



    As you will see it would crash on the approach, but not during the 4 pass thread cutting, and crash after upon retracting. Any suggestions?

    I have written a "manual process" in the meantime to get by, but not knowing how to fix issues with commonly used processes really bothers me.

  9. #9
    Join Date
    Aug 2010
    Posts
    18

    Re: Boring bar backoff value problem

    Hello Jim,

    It's been awhile since you helped me last, which I appreciated, would you happen to know how to solve a ID threading problem on a T2 controller?
    http://www.cnczone.com/forums/mazak-...ml#post1795562

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