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Don't buy Chinese Turbos, eh? (Bastard threads)

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  • #16
    Originally posted by The Metal Butcher View Post

    I think they (-----) reverse engineered it in it's entirety.
    You should add "poorly"

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    • #17
      Could have just tapped it out to something slightly larger and more standard.
      Kansas City area

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      • #18
        Modern machine shops, in china and everywhere else, don`t much care about the thread specs as being std.
        They care about making parts to the customer specified print, or sample.

        Someone somewhere specified xx.nn/yy threads of size aa/bb with thread pitch dd.
        So of course the chinese (cnc) machine shop made them to spec and shipped the parts.
        And got paid for them.

        Imho..
        The one who ordered the parts probably did a weak job on the specs/measurements, and thats likely why the threads are a mix, also called a bastard thread.

        Here in Spain, machine shops are extremely good.
        E.g. Most german auto mold manufacturing, and similar, has moved to Spain due to half the cost and at least equivalent or better quality.

        Here, normally the machine shops would check with the customer, with a bastard thread, asking if that is really what they wanted, and why, perhaps.
        Often, shops don´t know what the parts are for, and are usually supposed to ask very little.
        But they would alert the customer on bastard threads, for example, or on very tight mold specs like very deep pockets with minimal radius allowance or excessive accuracy callouts.
        Given that such features can cost vast amounts of money.

        An auto mold of 2.5 m long 30x40 might cost 300.000€.
        Excessive tight features in pockets might cost another 100k€, or more, depending.

        A lot of time strong trust is built over time, and the machine shops know a lot of the secret sauce the customers parts go into.
        Copying and selling customer info for cloning is very rare.
        This is very unusual for Spain, but machine shops work like that.

        Machine shops are also the best sector overall for paying their bills, in Spain, and as such get good credit from suppliers.



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        • #19
          I took a part to a local machine shop (NZ) and asked that they put a thread in the end and I specified the thread. They shook their heads and said such a thread had never been used. But they did check a couple of reference sources and found it listed, someone went to the cabinet where taps were stored and there, still wrapped in wax paper, was the required tap safe in box that bore a 1935 date.

          It was a Whitworth thread in a vehicle made in 1948. The thread was deprecated in 1936.

          Just because you cannot identify a thread does not mean it is a 'bastard' thread, it just means your knowledge is incomplete.

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          • #20
            Originally posted by The Artful Bodger View Post
            I took a part to a local machine shop (NZ) and asked that they put a thread in the end and I specified the thread. They shook their heads and said such a thread had never been used. But they did check a couple of reference sources and found it listed, someone went to the cabinet where taps were stored and there, still wrapped in wax paper, was the required tap safe in box that bore a 1935 date.

            It was a Whitworth thread in a vehicle made in 1948. The thread was deprecated in 1936.

            Just because you cannot identify a thread does not mean it is a 'bastard' thread, it just means your knowledge is incomplete.
            Complete my knowledge then artful.

            Minor diameter: .393"/9.98mm
            Pitch, near 1mm, perhaps a bit longer.
            21" Royersford Excelsior CamelBack Drillpress Restoration
            1943 Sidney 16x54 Lathe Restoration

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            • #21
              Originally posted by Toolguy View Post
              Could have just tapped it out to something slightly larger and more standard.
              ....and risk chips in the oil cooled body which would later flow in the engine?
              No thanks.

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              • #22
                Originally posted by The Metal Butcher View Post

                Complete my knowledge then artful.

                Minor diameter: .393"/9.98mm
                Pitch, near 1mm, perhaps a bit longer.
                Take another look at post #4.

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                • #23
                  Originally posted by The Artful Bodger View Post

                  Take another look at post #4.
                  Take another look at post #12.
                  21" Royersford Excelsior CamelBack Drillpress Restoration
                  1943 Sidney 16x54 Lathe Restoration

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                  • #24
                    Ummm, OK, but my primary message is still the same "Just because you cannot identify a thread does not mean it is a 'bastard' thread, it just means your knowledge is incomplete." As is mine.

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                    • #25
                      possible to use cerrosafe?

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                      • #26
                        Originally posted by The Artful Bodger View Post
                        Ummm, OK, but my primary message is still the same "Just because you cannot identify a thread does not mean it is a 'bastard' thread, it just means your knowledge is incomplete." As is mine.
                        You know what. I'll agree to disagree. If a brand makes a replacement part for a vehicle which is 99+% metric, to exacting specifications, and includes a thread that a machinist can not measure or match to any standard metric, SAE, BSP, or similar thread in a machinery's handbook, then yes. It is as bastard as they come.

                        I had access to all the tools. Test bolts of every variety. M11 taps. A lathe to make any test piece that I want. Ptich gauges in standard and metric. Mics, thread wires, calipers. Yet I still couldn't figure what it is (assuming it is something). How is your average mechanic supposed to figure out what is is? Even then. Even then, they're gonna be pissed as hell because the banjo bolt that came off their turbo was a standard M12x1.25. It's bastard.

                        I'm not sure why in an age of threadmills and CNCs, you are so certain that it is a standard thread. As Bented said, he could make a 3 start M15.72x1.123 thread if he wanted to. How can you be so certain an underpaid Chinese worker didn't fat finger the controller? Lastly, would that qualify as a 'bastard' thread?
                        21" Royersford Excelsior CamelBack Drillpress Restoration
                        1943 Sidney 16x54 Lathe Restoration

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                        • #27
                          Originally posted by buffdan View Post
                          possible to use cerrosafe?
                          Quite possibly. Dad got it fired up today and it didn't leak, so I guess we are GTG.
                          21" Royersford Excelsior CamelBack Drillpress Restoration
                          1943 Sidney 16x54 Lathe Restoration

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                          • #28
                            Web site engineersedge.com will tell you everything you need to know about 11x1mm thread.
                            John b. SW Chicago burbs.

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                            • #29
                              I wonder what's the possibility they had a dull tap that day?
                              Given the really strange major, minor, pitch diameters. but that still doesn't answer about the pitch.
                              I've seen that happen on vendor-supplied parts, where the manuf. is trying to stretch their tap budget.
                              No matter, the job is done and it works, and at the end of the day that's all that matters.
                              25 miles north of Buffalo NY, USA

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                              • #30
                                Originally posted by The Metal Butcher View Post
                                The thread is really shallow so it's hard to get a good reading.
                                Sounds like Whitworth, the rounded shape makes it look 'smoother'.

                                It doesn't exactly feel like 1mm pitch, but definitely not 1.5. It's sized almost exactly to 7/16-20, but that only goes in like 3 threads. WTH? Amazingly dad has an M11x1.25 tap which was a good fit but the wrong pitch. So we made too test samples from aluminum, M11x1, and M11x12.5. It definitely wasn't the latter, but it was close to the former. Definitely not the exact right pitch as it started to rub off dykem unevenly as it went down. I think it was closer to 1.1 or so.
                                Maybe 1.337?


                                BSP
                                1⁄16 28 0.907 0.3041 7.723 0.2583 6.561 5⁄32 4.0 6.6 6.8
                                1⁄8 28 0.907 0.3830 9.728 0.3372 8.566 5⁄32 4.0 8.6 8.8
                                1⁄4 19 1.337 0.5180 13.157 0.4506 11.445 0.2367 6.0 11.5 11.8
                                BSP is Whitworth which means it even appears different to 60 degree 'V' threads. Whitworth is 55 degrees and has rounded tips and hollows, that is visibly different too. Of course it is possible to cut a 60 degrees V thread and have it engage in a Whitworth thread but it only fits where it touches.

                                BSP is common in metric countries

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