Lathe - Boring Bar Setup
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  1. #1
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    Gents, I'm making good progress on learning my new cnc lathe but have come across a problem I can not figure out. I’m dead in the water.

    I have been turning OD stuff and drilling with no problem, now I need to do some ID stuff with a boring bar. The problem I am having is with the positioning of the boring bar tip (I think). The controller is a Fanuc Oi.

    Here is the issue: After setting the geometry offsets for the boring bar using the tool pre-setter the actual boring bar tip does not match the DRO position in X. The Z positioning is fine. For example, if I jog the boring bar tip to be at X0.00 (as best I can visually) the DRO has it as X.3742. If I jog the tip up to X1.000 (visually again) the DRO says X.5458.

    I have re-set the geometry offsets with the pre-setter many times, same result. I made sure there are no erroneous wear offsets. There is a variable in the geometry offsets for the tip position; 1, 2….7,8 for the different quadrants. I’ve tried setting this to “2” and others but still get the same results. I am in dire need of some help!

    Mark

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    Nat, Have you checked the DRO position if you call the boring bar tool number in MDI?

  3. #3
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    Yes, just did. Same results.

    T2727
    X0

    Same results.

  4. #4
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    You got me curious now....
    If you bore a hole , measure it, note the DRO position.....
    Under those conditions, the DRO is off??
    That would have me baffeled

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    Yes, it's way off. The particular hole I am trying to bore is .4900 in diameter. When the boring bar comes in at X.4900 (per the DRO) you can visually see that the actual position is @ X 1.000. I am totally stumped.

    Mark

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    dont use the tool setter try touching off the tool manually and se eif you get the same result.

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    btw, I checked the other boring bar I have in the turret and it is way off too. I think the problem is somehow related to how I am setting up the bars but I don't know what I am doing wrong. Here is my exact process I am using. The boring bar is positioned in the turret "face down", ie; if you are looking straight at the spindle the insert is on the bottom with the tip cutting at 3:00.

    a) in MDI mode call up bring bar (ie;T2727) so the controller knows exactly what tool I am using. This step is probably redundant in that when you bring the pre-setter down it automatically goes to the offset page and goes to that specific tool.

    b) jog in the boring bar close to the presetter. The presetter has 4 sensors. Looking directly down at the presetter there are top/bottom/left/right sensors. For the boring bars I use the right and bottom sensors. After positioning close to them I jog into them to set the Z via the right sensor and X via the bottom sensor. I can visually see the offsets being set in the controller.

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    Thanks Mfassler, I know I should now how to do that but I must have missed it in the training. Can you tell me the exact process for doing that?

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    Sounds to me like you may need to recalibrate your presetter. Instructions should be in the manuals.
    Ken

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    For the tool offset, what happens if you change the x value from a positive to a negative, or vise-versa.

    Say its .6962, change it to -.6962

    What effect does this have to position now?

    On my lathe (different brand) I have to tell in my tool set-up if I'm cutting on the right or left side, which means the x-positive or x-negative side of the part.

    WOO-HOO, just hit my 100 post.....I'm Hot Rolled Now.

  11. #11
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    Natchamp, is this the first time you are using the setter for an I/D tool?

    If so, the parameter may be off.
    you need to find that parameter and set is correctly, sounds to me like it is off.

    I've had that happen to me many times on Mazaks, Moris, Okumas , Femcos, etc. etc. etc

    do what mfassler suggests, then adjust your parameter for that contact on the tool setter accordingly.

    best wishes my friend.

    SteelCutter

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    Natchamp - In your first post you say that when you jog the tool to X0 the DRO shows X.3742, could that be -.3742, not +.3742? If it is -.3742, then I think greyghost is correct.

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    Nat
    refresh my aging memory...what machine and control?

  14. #14
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    Brand new Femco HL25 Durga with a Fanuc Oi control. I think mt presetter needs to be calibrated for the bottom sensor. That's what appears to be the problem anyways. Yes, it is the first time I'm using ID tools (other than drills) on the machine. To get going I just adjusted the X wear offset way out. I'll follow up with Femco to have them calibrate the sensor.

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    I was just a bit curious as I have a brandy new Daewoo with a 0iTc control. I have had Z move a bit and couldn't figure it out till I called that tool an dthen set the G54 Z zero.
    Drove me nutz till I figured out what I was doing wrong.
    My Haas also has a tough probe but I've been toooo chicken to use it. Set them tools the old school way...

  16. #16
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    if you are using the "other" side of the presetter, (not the side for turning tools) there is a param for tool sensor size.

    Possibly it thinks you are still touching the wrong side and setting the offset based on that. Should be easy to tell. By your numbers, is the tool probe about 1/2" thick??


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