Welcome to Our Community

Some features disabled for guests. Register Today.

Discussion on ER Collets

Discussion in 'CNC Mills/Routers' started by CNCMD, Aug 20, 2018.

  1. CNCMD

    CNCMD Veteran
    Builder

    Joined:
    Jul 29, 2017
    Messages:
    110
    Likes Received:
    74
    Hi All - I wanted to share an experience with you all and get some feedback/discussion on the matter. Been working on some cool workholdings, and setups and as I was working on this with having the dial indicator out, I wanted to conduct some spindle runout testing.

    I was immediately concerned about some excessive run out identified past the collet. What I mean by this was the spindle did not have any noticeable run out, but the collet did. I was kind of shocked as this was a Amana Collet, and Maritool Collet nut, both higher end stuff (I'm just saying these were not $2 aliexpress parts). Upon trying other collets and nuts, same brand, the runout diminished to zero. Again, I was even more surprised.

    I came to see that the tightness of the collet plays a critical part in the runout, and also just luck of the draw in how its positioned upon tightening.

    Does anyone have any interesting stories about this, best practices, etc.
     
  2. GrayUK

    GrayUK Openbuilds Team Elder
    Staff Member Moderator Builder

    Joined:
    May 5, 2014
    Messages:
    1,430
    Likes Received:
    461
    That throws up a mess of concern I think. I'm about to order a Spindle with an ER16 collet. So I'll prepare myself for some investigation before using it. Could you see any error in the work carried out because of the Run-Out? Do you think they can be Over-tightened? Does that mean you will now only use the Zero collet and nut?
     
  3. CNCMD

    CNCMD Veteran
    Builder

    Joined:
    Jul 29, 2017
    Messages:
    110
    Likes Received:
    74
    I don't want to cause alarm to anyone. ER collets are deemed the most accurate of any collets/ bit holders. I have not noticed any errors in my work, hence my surprise. I normally can hold tolerances to .01mm with my machine. Any variance is often from not having my steps as tuned/tested, but still, .01mm is air....lol.

    I can't imagine you could tighten them anymore than I do, I get them good and tight, especially while I was testing last night.

    No I will not just use the one collet and nut, the issue really is how the bit seats on that exact time. Honestly this is a huge reason that you see tool holders on other machine. Aside from the speed in changing bits, it allows you to put the tool in the collet, adjust it for runout, and then leave it be. Not really practical for home usage (money wise).

    Right now I'm just thinking about all this, as it came up last night and I was just so surprised by it all.

    There are also ER nuts that utilize ball bearings to ensure the collet sits "square".
     
    GrayUK likes this.

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice