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ER Collet nut torque.

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  • ER Collet nut torque.

    After finding a number of references to ER collet nuts "must be wanged up real tight" I thought it would be good idea to find out and share what people really think should be the torque and how to apply tight

    Centaur precision tools say this Max. Tightening Torque (ft. lbs.)

    ER11 -20
    ER16 - 40
    ER20 -60
    ER25 - 70
    ER32 -80
    ER40 -90

    parlec say this

    ER11 -22
    ER16 - 52
    ER20 -74
    ER25 - 86
    ER32 -100
    ER40 -146

    Regofix give slightly different numbers again

    all of them warn against overtightening!

  • #3
    My experience with ER32 collets and carbide endmills is that if you don't take them up in the ball park of those recommended numbers you'll get slipping, at least with high RPM and heavy cutting.

    That's a pretty hard pull on the typical supplied ER32 wrench though, they really should make them longer.

    I also use ER16's a lot and I don't think I'm pulling them as hard as the recommended numbers, at least not on small endmills. Also the ER16 holders that have the M style nuts (smaller) don't have as big threads and bodies as the hex nuts, taking those to that full spec seems like it might be too much.

    Paul T.


    • #4
      how many here use a torque wrench on a collet...
      where on earth do you get a torque wrench attachment?


      • #5
        Originally posted by derekm
        how many here use a torque wrench on a collet...
        where on earth do you get a torque wrench attachment?
        No problem! Just recalibrate your fingers every so often.

        Yeah, I know this is the kind of discussion likely to set off the fireworks. But seriously, as a machinist you depend on feel for a lot of things - micrometers, especially depth mics, how loose a fit something is in a hole, how much a step that is between surfaces. If you actually do use a torque wrench from time to time you can associate a pressure on the handle within a range and duplicate that (again within a range) on something else.

        No, it's not on the numbers and if you actually torqued it with a wrench you'd find out how much you're off, but it will get you in a useful range for things like this.
        "People will occasionally stumble over the truth, but most of the time they will pick themselves up and carry on" : Winston Churchill


        • #6
          recalibrate your fingers ! LOL Yes I know what you mean.
          80ftlb is two grunts with a 3 ft long wrench handle. (grunts being the finger unit of force) 15ftlb is 1/2 a grunt with a 6in wrench.

          but I want to do it properly at least now and then. particulary as the feel is different when you are doing it up at chest height on a mill compared to low down tighteniing a wheel nut or a flywheel bolt, which is most of the places I 've tightened up around and over 50 ftlbs.