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Holding A Carbide End Mill

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  • Holding A Carbide End Mill

    Not wanting to hi-jack the other collet/end mill thread, I have a question. This is also not to fuel the collet/end mill holder debate, much like the Ford vs Chevy vs Dodge debate, the correct answer is depending on your point of view.

    How do you hold a carbide end mill? All of the carbide end mill I get, mostly from SGS or TitanUSA, do not have the Weldon style end mill shank, there is no set screw perch. I do a lot of thinner gauged stainless steel work and I normally use an ER-40 collets to hold them. I called one of the manufacturers, they were adamant that grinding a notch in the shank would cause the end mill shatter. Most the end mills I use run between 1/8" to 1/2" (all straight shank). I've never had one slip (knock on wood), but I'm going to be mill some 3/8" and 1/2" stainless plate and not wanting any problems, so what do you do?


  • #2
    I don't see where you should have any problems with the setup your using.

    Are you having problems with them slipping now???
    It's only ink and paper


    • #3
      Carbide End Mill

      Use the ER collets. They are a very secure holding device. I use a lot of carbide endmills and have no problems with R8, ER of various sizes and DA of various sizes. From an engineering standpoint, I think the ER collets grip better and are more accurate, but in actual use, I haven't had any problems with DA collets. Grinding the groove across the shank for a Weldon holder won't break it, but tightening the set screw is likely to.
      Kansas City area


      • #4
        The ER collet will work fine for you with the carbide endmill, but if you are taking hard cuts, two steps are important.

        Clean the endmill shaft and collet insides with laquer thinner or some other oil removing solvent before assembling.

        Make sure to torque the the nut on the holder to the recommended range for that collet size. This is a lot higher than most people realize. For an ER32 collet its in the range of 65-80 ft-lbs, and much higher than that for a ER40 collet. That's a really hard pull on the typical wrenches they supply for these holders.

        If you have an R8 spindle, its not really possible to get that high a torque without shearing the index pin in your spindle (yes, I learned this the hard way).

        I made a vise mounted fixture to tighten my ER holders outside of the spindle. I used a 30 taper male to R8 female adapter to make the fixture, there is a guy on ebay who sells these adapters pretty cheaply, I just trimmed the excess off of it and made some mounting blocks for it so I can clamp it in my vise.

        Good luck-

        Paul T.