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  1. #1
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    Question Pinch (Balance) Turning?

    How many people pinch turn with their roughing tool leading the finisher (in Z)? Does anybody even their tools evened out (in Z) and balance the cutting forces (ie; 180 deg cut per tool, equall chip load) or does the rougher have to lead? I am trying to grasp the concept of "pinch turning". We currently run with the rougher leading 0.03" in Z ahead of the finisher, where we have to pull the rougher out before any wall or X move. Not having much availible machine time to test this thought, who out there truely pinch turns? With the tools lined up in Z (+-.0005), wouldn't the inserts last longer, parts come out straighter, or rounder? Don't the Swiss machine (Star SV) come from the factory with the turret lined up with the gang post? Do we need to shim the rougher ahead, or will balancing the tools work?

  2. #2
    Moderator tobyaxis's Avatar
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    Balance Turning on swiss is easiest when you set your finish tool .005 Z+ from the rough.

    The G-Code call G121 or what ever your designation should take care of the rest.
    Toby D.
    "Imagination and Memory are but one thing, but for divers considerations have divers names"
    Schwarzwald

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

    www.refractotech.com

  3. #3
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    The "Reality" of Pinch turning as you've described would be close to impossible. If your tool post were factory aligned the tool measuring would leave way to much to chance. Not to mention many other possible causes that would leave you with the opposite of the desired affect i.e. your finish tool leading with your rougher doing nothing at all. So I would concure with leaving your finisher some .005-.03 "behind" your rougher.
    HTH.
    Good luck.

  4. #4
    Moderator tobyaxis's Avatar
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    Quote Originally Posted by ProProcess View Post
    The "Reality" of Pinch turning as you've described would be close to impossible. If your tool post were factory aligned the tool measuring would leave way to much to chance. Not to mention many other possible causes that would leave you with the opposite of the desired affect i.e. your finish tool leading with your rougher doing nothing at all. So I would concure with leaving your finisher some .005-.03 "behind" your rougher.
    HTH.
    Good luck.
    I have a question for you. Have you ever used a Swiss with Gang Tooling???

    Balance Turning is using two opposing tools to Rough and Finish at the same time. Some swiss do not have this ability, but seeing that this gentleman is asking for advise on Balance Turning I can assume that his machine does.

    Assuming that he has the Geometry Offsets and Tool Heights/Center Lines he is good to at least try Balance Turning.

    The only thing he needs to do is place a .005 shim in front of the finishing tool shank before tightening the clamping screws. Call the Balance Turn G-Code then Cancel the command when the profile is complete.
    Toby D.
    "Imagination and Memory are but one thing, but for divers considerations have divers names"
    Schwarzwald

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

    www.refractotech.com

  5. #5
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    Quote Originally Posted by tobyaxis View Post
    I have a question for you. Have you ever used a Swiss with Gang Tooling???

    Balance Turning is using two opposing tools to Rough and Finish at the same time. Some swiss do not have this ability, but seeing that this gentleman is asking for advise on Balance Turning I can assume that his machine does.

    Assuming that he has the Geometry Offsets and Tool Heights/Center Lines he is good to at least try Balance Turning.

    The only thing he needs to do is place a .005 shim in front of the finishing tool shank before tightening the clamping screws. Call the Balance Turn G-Code then Cancel the command when the profile is complete.
    Yes I have.

    The gentalman is asking about:

    Quote Originally Posted by sidswiss
    evened out (in Z) and balance the cutting forces (ie; 180 deg cut per tool, equall chip load) or does the rougher have to lead? I am trying to grasp the concept of "pinch turning".

    If you are trying to have both tools on the same exact z plane, this will be difficult at best. If either of the tools shifts .0001" you will not be doing the above mentioned operation and one tool will be performing all of the work. The common practice of having the rough tool lead will assure that this does not happen. By all means try away, but i thought the gentalman was looking for some conceptual feedback on the practice of pinch turning as he said he did not have much available machine time to test.
    At any rate Good luck and let us know how you make out.

  6. #6
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    If your turning at .004 to .008 ipr, each tool would take .002 to .004 ipr so you have up to .002" of wear before the "balanced" part would fail. As one edge starts to wear, the other wears as well, prolonging the tool life. Mind you, if your using say a .015 tnr rougher and a .008 tnr finisher, you could use that differance(.006) in X for a good surface finish with the finisher, but the bulk of the stock is removed with both tools using the same force and chip load. Any thoghts?

  7. #7
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    Quote Originally Posted by sidswiss View Post
    If your turning at .004 to .008 ipr, each tool would take .002 to .004 ipr so you have up to .002" of wear before the "balanced" part would fail. As one edge starts to wear, the other wears as well, prolonging the tool life. Mind you, if your using say a .015 tnr rougher and a .008 tnr finisher, you could use that differance(.006) in X for a good surface finish with the finisher, but the bulk of the stock is removed with both tools using the same force and chip load. Any thoghts?
    Conceptually it sounds logical and well worth attempting.
    All operators and setup personnel on all shifts will have to be on the same page with respect to making offsets, changing tools and or tool geometry.
    Again I say good luck and let us know how you do.

  8. #8
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    Quote Originally Posted by sidswiss View Post
    How many people pinch turn with their roughing tool leading the finisher (in Z)? Does anybody even their tools evened out (in Z) and balance the cutting forces (ie; 180 deg cut per tool, equall chip load) or does the rougher have to lead?
    Yes, well worth attempting. But again, with limited machine time to test, I was hoping someone else out there has already attempted it. Or at least thought of it. If anyone out there has the time and inclination to try this before I do, let us know how it works. Better cycle times, anybody?

  9. #9
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    Quote Originally Posted by sidswiss View Post
    Yes, well worth attempting. But again, with limited machine time to test, I was hoping someone else out there has already attempted it. Or at least thought of it. If anyone out there has the time and inclination to try this before I do, let us know how it works. Better cycle times, anybody?
    Use to make shafts 3 inches long starting from .08 Dia turned back to about 2.875 to a .375 Dia.. Balance Turning was the only way to hold .0002 from one end to the other in Inconel X750. Not to mention the .01 Max Corner Radius call. The Rough was taking about 2/3 the load while the Finish was taking the remaining 1/3. See attachments.

    We used Sandvik .5 Square Shank Tools, The I.C. was .375.. Inserts were Cermit. CCGT I think. It has been a long time.

    The total quantity was 10,000 parts and they wanted about 1,000 per month.

    As long as your machine supports Balance Turning try it. If it doesn't you could be in for a major headache.

    I will look to see if there are any parts floating around. We named them anteni
    Attached Thumbnails Attached Thumbnails IMG_5940.jpg   IMG_5949.jpg   IMG_5951.jpg   IMG_5954.jpg  

    Toby D.
    "Imagination and Memory are but one thing, but for divers considerations have divers names"
    Schwarzwald

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

    www.refractotech.com

  10. #10
    Moderator tobyaxis's Avatar
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    Have you tried the Balance Turning yet??
    Toby D.
    "Imagination and Memory are but one thing, but for divers considerations have divers names"
    Schwarzwald

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

    www.refractotech.com

  11. #11
    Quote Originally Posted by tobyaxis View Post
    Balance Turning on swiss is easiest when you set your finish tool .005 Z+ from the rough.

    The G-Code call G121 or what ever your designation should take care of the rest.
    I have a question for you. I need some help with
    Pinch turning. I have never programed pinch turning
    Before. I'm looking for some advice please

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