If the TTS is so awesome, why do I get horrible chatter with a 3/8 end mill? - Page 3


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Thread: If the TTS is so awesome, why do I get horrible chatter with a 3/8 end mill?

  1. #25
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    "In fact, even with a somewhat firm crank on the drawbar, even a 3 flute 1/4" endmill at 5k rpm, .27 DOC, .08 WOC 22ips can pull out the TTS holder." - You are doing something VERY wrong then! I use TTS holders almost exclusively, and I have NEVER once had one pull out on me. I routinely run 1/2" endmills, doing 1/2" deep slotting at 15-20IPM. I also run carbide three-flutes, 0.250" deep, up to 70IPM, also slotting, and have NEVER had one pull out. Proper drawbar torque is at least 25ft-lbs, NOT a "somewhat firm crank". You NEED to tighten the drawbar better.

    Regards,
    Ray L.



  2. #26
    Registered Scott_M's Avatar
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    What size wrench are you using on the drawbar ? As in, length of handle ? If you are using the little 6" long wrench that came with the machine then I agree that the drawbar is not tight enough. If you have a torque wrench it would be interesting to find out how much torque you are getting with a firm crank. Tighten as usual then loosen with the torque wrench to find out what you have been using.
    I also have never had a TTS pull out and I have done some pretty serious cuts.

    I also think you may have misread the use of the lapping compound. You would put it on the shank of the TTS not the endmill and only if all other reasonable means failed.

    Scott

    www.sdmfabricating.com


  3. #27
    Gold Member dertsap's Avatar
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    Quote Originally Posted by beanbag View Post
    Dertsap,

    I saw on the CGS web page that if the length of cut EXCEED 1.5 diameter, is when you should go conventional. Does that mean I should use a conventional cut if I do a profile finish pass?

    .
    sorry i wasn't thinking and when i said "below" i meant deeper .
    generally even if your running deeper than 1.5 dia its not really necessary on a finish pass. But if there is chatter then it very well could be the cure to run conventional no matter the depth
    I use the CGS 55 degree on a daily basis and rarely hear them chirp unless they are being pushed hard and when i say hard i mean hard , so i find it highly unlikely that your problem would be a tool issue .

    is the chatter happening on the finish passes or just on the rough pass , also are you plunging the end mill to depth in the material or are you leading in , ramping to depth ?


    .

    A poet knows no boundary yet he is bound to the boundaries of ones own mind !! ........


  4. #28
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    I need to check with a torque wrench, but "somewhat firm crank" for me means about 20 something ft lbs, and "really leaning into it" means about 35+. I have not had a pullout when "really leaning into it", and it fixes the chatter a small fraction of the time.

    I never get chatter on a finish pass, and usually I aim for about 30% tool width when roughing. Sometimes I have to stick the end mill into a corner (higher engagement angle) and that increases the chance of chatter. (obviously)



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    I think the ER20 TTS holder is more prone to pullout than the weldon type because it is longer. Pullout happens not from the static axial force, but from the endmill wobbling back and forth at the spindle rpm (from the point of view of the spindle). Since the ER20 holder is longer, the wobble force is greater.



  6. #30
    Registered Don Clement's Avatar
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    Quote Originally Posted by beanbag View Post

    I did see Tormach's guide on drawbar torque. That study seems like something I would do, and this fact worries me, because I am not an engineer. A REAL company with engineers like Bridgeport or Haas would not recommend some novel micky mouse solution like putting lapping compound on your end mills.
    Anonymous and not an engineer. Who is REAL here?

    Last edited by Don Clement; 11-01-2011 at 01:09 PM.


  7. #31
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    Of the two Tormachs I use, the more chattery one, which I call Chatter McChatterton, seems to have really long ER20 holders. They measure 2.5" from TTS collar to the tip.



  8. #32
    Registered Don Clement's Avatar
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    When you are anonymous, you can post anything about anything. Who’s going to believe you? However the thread title gets repeated and it's déjà vu all over again.



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    Thank you for your helpful and insightful comments.



  10. #34
    Gold Member dertsap's Avatar
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    this may be as obvious as the tool plunge question i asked but have you tried to swap holders and document the difference of how each machine performs

    A poet knows no boundary yet he is bound to the boundaries of ones own mind !! ........


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    Quote Originally Posted by dertsap View Post
    this may be as obvious as the tool plunge question i asked but have you tried to swap holders and document the difference of how each machine performs
    As I mentioned a while ago, I swapped between different holders, but that is only within the set that comes with each machine.
    I kind of came to the realization yesterday that the set that comes with the more chattery machine looks longer than the set that comes with the less chattery machine. I'll have to measure the length on the other machine to see if they are the same. No, I can't take the collets on one machine and bring them to the other. What does your ER holder measure out to?

    Edit: I see I didn't fully answer your question last time, but this chatter is happening during the "regular" part of the cut. I'm not complaining about lead-in chatter only.



  12. #36
    Gold Member dertsap's Avatar
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    Quote Originally Posted by beanbag View Post
    No, I can't take the collets on one machine and bring them to the other. What does your ER holder measure out to?

    .
    I don't have a tormach so i can't answer that question , I work with much larger machines .
    So you can't take a holder from one machine and swap it with another ?

    A poet knows no boundary yet he is bound to the boundaries of ones own mind !! ........


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If the TTS is so awesome, why do I get horrible chatter with a 3/8 end mill?
If the TTS is so awesome, why do I get horrible chatter with a 3/8 end mill?