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ER collet system

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  • ER collet system

    Hi Guys,

    I have a question on ER Collet systems.

    I have a small mill with a MT2 spindle, I have been using MT2 collets, which most of the time do me well, apart from now and then I get an end mill that will just not grip well, which is very annoying.

    So it was suggested to me to use an ER32 collet system, so I have been looking into this.

    Couple of things I have noticed (apart from the price) I don't have a massive amount of space between the head and the vice so I did notice they do take up some of this space, where as the MT2 Collets I use at the moment don't take up any space.

    But while looking at them, and this is the main question, what is the difference between them all, ER16, ER20, ER32, Er40 etc


  • #2
    Diffrence is just size. IIRC the number is the max mm that a collet comes in.

    And no, ERx collets will not work in ERy or visa versa.

    Also, the 32 and 40 take *insane* amounts of torque to fully tighten, something like 100ft/lbs+ for ER40. 16/20 are not too bad.

    Some sizes are much more common on bargin sites too, So you might wanna look into what collet set you plan to buy first.
    Play Brutal Nature, Black Moons free to play highly realistic voxel sandbox game.


    • #3
      Thanks for that, that would make sense, 16 or 20 would be more than enough for what I do and I can never imagine I would want to use anything with a 32 dia shaft, my mill would never cope...!



      • #4


        • #5
          The number is the max diameter of the collet, NOT the holding size.
          ER16 will go up to 10mm or 3/8" +
          ER20 will go up to 13mm or 1/2" +
          ER25 will go up to 16mm or 5/8" +
          ER32 will go up to 20mm or 3/4" +
          ER40 will go up to 26mm or 1" +

          These are the popular sizes, some makers do list bigger sizes in each range but they are not common.

          There are no gaps in a set so they can hold all sizes of drills or cutters.

          They are also one of the few work holding and tool holding systems making them ideal for swapping between lathe and mill.

          Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.