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ER series - common 8° angle?

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  • ER series - common 8° angle?

    I "think" I know the answer to this question but could use some reassurance. All the collet series of the ER type have the same rear taper angle, correct? In other words, a holder with a socket for accepting ER20 will be made to the same 8° angle as a holder with a socket for accepting ER16 or ER25. The only difference is gage size for each series. Yes or No?

  • #2
    Seems so: - 8 degrees from centre, 16 degrees included angle.
    All of the gear, no idea...


    • #3
      Yeah, that is how I read it too. I have an ER collet arbor adapter, and I was thinking of using it as a gage while mounted in my headstock to set the compound angle. The adapter would be for a different ER size, though.


      • #4
        I have made an ER-50 collet chuck. Actually I have made three of them.
        One for my WB w
        Workshop 9" lathe, One for my SB Heavy 10 Lathe and one for the index head on my Burke mill.
        Setting the compound angle is not trivial and must be sone wit some care of the collets will not hold the work tightly and you can get rock.
        I finally use a DI. I have a shop made DI holder that goes into my QCTP.
        I mounted an ER-40 collet on a piece of ground rod in a collet in the lathe. I slipped the ER-40 collet onto the ground rod and the aligned the compound using the DI.

        This worked well
        Jim B