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  • #16
    To summarize; you have an R8 spindle, a (Chinese?) R8 to ER40 adopter, and a set of Chinese ER40 Collets. And you expected great precision?

    I would start with the R8 spindle and check the run out there.

    Then check the run out on the R8 to ER40 adopter.

    If both of them check out OK, then you are left with the nut and the collets. Have you checked all or a significant number of the collets or just a few? If all the collets measure about the same amount of run out, then I would start to suspect the nut. If they vary by significant amounts then is is probably the collets.

    Try mounting the collets at different rotations in the adopter and see if the error stays with the adopter (and spindle) or if it rotates with the collet. That will tell you something.

    Another thing to do is check close to the collet and then about two inches further out. This will detect any angular discrepancy.

    Oh, and are you sure your test pins are OK? And you did clean everything well first. It doesn't take much dirt or swarf to keep a collet from seating properly.

    Start thinking about complaining to the seller, if you can. But you should have a good idea of exactly where the problem is first.



    Originally posted by davidwdyer View Post
    I just bought a set of ER 40 Chinese collets with an R8 holder which fits in my Bridgeport.

    There seems to about .0018 run out on whatever I hold in them. The 1/2 inch collet is worse.

    Now I am beginning to suspect my 5C collet set which gave me some trouble in the past but I blamed on my own work.

    Anyone else have experience with such collets?
    Paul A.
    SE Texas

    And if you look REAL close at an analog signal,
    You will find that it has discrete steps.

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    • #17
      I bought a set of MT collets from CDCO for my Logan lathe.
      Some runout a little over .001" but most don't.
      All needed burs cleaned off of them.
      Pretty good for Chinese.
      Probably just lucky.
      Bill
      I cut it off twice and it's still too short!

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      • #18
        Originally posted by Rich Carlstedt View Post
        Any collet with 2 tapers will never be as accurate as a single taper collet.
        As in real life, one can never serve 2 masters.

        Rich
        That's funny!

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        • #19
          I buy Chinese collets etc ,even bought a collet chuck for 5 collets complete with a d1-4 backplate and they all seem to be good to me, but then I am not a real engineer. From what I have been told when China and India started making these engineering tools chucks, collets cutting tools and holders etc they along with a lot of bigger stuff they made was always a case of you get what you pay for, meaning be prepared to clean up ragged edges etc. .However It is my understanding that year on year with a government sponsored heavy investment programme things gradually improved. This reminds me of when I was a young man when Japanese stuff was always treated with great suspicion. As we know those days are long gone and buying anything machine related is something we queue up for, and something renowned for holding it's price too. so I forsee a day when this could happen with the Chinese and Indian firms. John Stevenson would know a lot more about this. Alistair
          Please excuse my typing as I have a form of parkinsons disease

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          • #20
            You are holding something that's the full length of the collet, aren't you? ER are designed to contact full-length, if not they can easily show run-out! If holding short workpieces / tools I put a "slug" the same diameter (usually the shank of a broken/worn-out drill) in the "back" of the collet so it tightens down parallel. single-taper collets don't suffer the same way, as most only grip at the very tip anyway...

            As suggested earlier, it's worth checking the inside of the holder's taper with your best DTI to be sure it's concentric (and if it isn't, checking the inside of the machine's spindle taper) before you condemn the collets - with a full-length grip the blued rear taper (into the holder) should show contact all the way along if the angles are right!
            Rules are for the obedience of fools, and the guidance of wise men.

            Holbrook Model C Number 13 lathe, Testa 2U universal mill, bikes and tools

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            • #21
              Originally posted by garyhlucas View Post
              Maritool doesn't make their own collets either. Apparently no one in the US makes them any more.
              Well I never said they did [emoji6]

              But I hear their quality is best-in-the-business

              Sent from my XT1053 using Tapatalk

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              • #22
                I recently acquired my first mill, an elderly Rong Fu 25. Having seen the prices of tooling here in New Zealand, I bought an ER25 holder and a complete set of collets, from China. The holder was US$35-odd, and the set of 15 collets US$29, the price of a single collet locally. Postage was free, though how airmail from China to NZ could take five weeks is a bit of a mystery.

                The biggest collet was stamped 16mm, but was in fact a mis-labelled 15mm. I sent the supplier a photo and he promptly sent a correct replacement with no hassle.

                I have just checked the run-outs on the four sizes of cutters I have. The best is the 8mm, which has about 0.005mm, and the worst by far is the 6mm, with about 0.06mm.

                I think that for the money I have done OK, since I don't have any need for greater accuracy.

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                • #23
                  Originally posted by garyhlucas View Post
                  Maritool doesn't make their own collets either. Apparently no one in the US makes them any more.
                  It is my understanding that Hardinge still makes collets in the U.S. If someone knows otherwise, I'd be interested in hearing the details. But I'd also want to know the source of such information. For example having a Hardinge branded collet marked as made in some other country or first hand information from Hardinge to this effect.
                  David

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                  • #24
                    Originally posted by Rich Carlstedt View Post
                    Any collet with 2 tapers will never be as accurate as a single taper collet.
                    As in real life, one can never serve 2 masters.

                    Rich
                    And those have 4 tapers in the holder..... 2 for the collet (one in nut and one in body), and then the 2 threads of the collet nut and body also have a centering action for the nut on the body
                    CNC machines only go through the motions

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