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Help! Crossthreaded ? My burr casing

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  • Help! Crossthreaded ? My burr casing

    I just bought a second hand grinder, got it home and pulled it apart to clean, (was absolutely filthy) all was going fine until I was putting it back together, got the burr casing all the way on and in the process of backing it off to set the stop screw and something bound up - not sure if a foreign object or if it somehow managed to crossthread itself?? Either seems implausible, but it has completely jammed up and I cannot move the top casing AT ALL 😭😭😭 I am in tears, I don’t know what I have done wrong, I am devastated.

    it is a K3 push 2013 model. All internals looked excellent when I had it apart.

  • #2
    If there's any ground coffee whatsoever in the threads, it will seize up on reassembly. It's actually petty much impossible to cross thread one.

    Older versions which use aluminium in conjunction with brass are notorious for thread galling and it can sometimes be the end of the road for them.

    Hope it's the former for you rather than the latter.

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    • #3
      I had just spent 40 minutes cleaning it....... ��

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      • #4
        Originally posted by Trixitrine View Post
        I had just spent 40 minutes cleaning it....... ��
        Will depend on how well you did it...

        Unless the threads were absolutely spotless, you're in trouble and may need the assistance of a tech. Regardless, I have see a few with threads buggered sufficiently so as to warrant binning.

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        • #5
          Well it was absolutely filthy, and I couldn’t get every grain out of it, but I really thought the threads were really clean. They looked to be in really good condition, I screwed it on all the way without much issue, it’s only when I changed directions to set the stop screw that it went bad :-/

          I went ahead and tried it out and it is working, and at not a bad point grind setting wise...l like I could live with it as it is, but I cannot adjust the setting at all.

          Click image for larger version

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          • #6
            Originally posted by Trixitrine View Post
            I had just spent 40 minutes cleaning it....... 
            First, I don't know that model so this may not help much. I am assuming it is a large diameter fine thread that is jammed (that may be wrong). If my assumption is correct, head down to a hardware store / automotive store (a good one, most have crap alternatives - which aren't) and get some Penetrene. Penetrene is non-corrosive (it is a very, fine machine oil) and will separate almost anything given a few applications and enough time* - even under water. It comes as a spray and as a drop bottle - I reckon the drop one works better, however I successfully used the spray one today on a trailer hitch that spent 15+ years stuck together. Either will work well enough for your use.

            Put a couple of drops on the troublesome area and leave it overnight (or longer). Rock the stuck parts back and forth as far as you can without using silly amounts of force. Repeat if necessary. I reckon at worst it should clear by day two, however overnight works on most things.

            Good Luck.


            TampIt
            * WA Water Corp (what it sounds like) had to use the main (underwater) valves on the Perth to Kalgoorlie pipeline a while back. 106 years of corrosion without being moved. It took my mate three weeks of once a day Penetrene to free them without using any power tools. Then the valves spun by hand just like new (I was there). Pretty impressive stuff... Oh, and no, there are no true alternatives - ask any qualified corrosion engineer (like my mate). Needless to say, virtually anything stuck gets shifted if you are patient.

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            • #7
              What I would do is the following:

              If you can wind it back out and off then do so.

              Then get a fine pointed instrument (a variety pack of picks, pokers, and hooks can be bought cheaply at Bunnings) and a magnifying glass. Clean out all threads one by one. Apply food grade grease to both sets of threads. Look for the thread feed in point with the magnifying glass- slowly move the other thread into it, rotating back and forth as you go. If you feel any resistance back it out immediately. Keep proceeding rotating back and forth. This is likely to re-cut in the original threads and you should be back in business.

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              • #8
                Thankyou, I will look into that!

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                • #9
                  Originally posted by Gavisconi007 View Post
                  What I would do is the following:

                  If you can wind it back out and off then do so.

                  Then get a fine pointed instrument (a variety pack of picks, pokers, and hooks can be bought cheaply at Bunnings) and a magnifying glass. Clean out all threads one by one. Apply food grade grease to both sets of threads. Look for the thread feed in point with the magnifying glass- slowly move the other thread into it, rotating back and forth as you go. If you feel any resistance back it out immediately. Keep proceeding rotating back and forth. This is likely to re-cut in the original threads and you should be back in business.

                  i absolutely can’t get it out/move it at all :-( it bound up very suddenly and firmly. I tried to go back and forth when I felt it grab, to no avail. Thankyou for your detailed answer, and if I can get it out trying the penetrol suggested, I will then examine the thread

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                  • #10
                    Penetrene not penetrol

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                    • #11
                      Preferably, I would use a dry Teflon based lubricant rather than a wet one. At a pinch, you could also use Graphite Powder available from most hardware stores (which is used as a dry lube for locking mechanisms of all types)....

                      Mal.

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                      • #12
                        Originally posted by Dimal View Post
                        Preferably, I would use a dry Teflon based lubricant rather than a wet one. At a pinch, you could also use Graphite Powder available from most hardware stores (which is used as a dry lube for locking mechanisms of all types)....

                        Mal.
                        Usually I would agree, however the fine thread on most grinder burrs is too fine for the dry stuff to get in (even dry Lithium paste usually does not penetrate in far enough), so they do not often work in that situation. The OP use of the word "jammed" usually requires Penetrene. Cleaning up any extra "wet stuff" is pretty easy given her 40 minutes to clean it out so far... She sounds very thorough, if a bit unlucky. Happy to be proven wrong, as I do not know that particular grinder at all.

                        TampIt

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                        • #13
                          Using a short handled ~9.0mm artist brush is what I use and it gets right into the thread valleys without problem.
                          The dry Teflon based lubes use a solvent carrier that evaporates very quickly, and leaves the lube behind...

                          Mal.

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                          • #14
                            Originally posted by Trixitrine View Post
                            i absolutely can’t get it out/move it at all :-( it bound up very suddenly and firmly. I tried to go back and forth when I felt it grab, to no avail. Thankyou for your detailed answer, and if I can get it out trying the penetrol suggested, I will then examine the thread
                            Have you tried using a vise? I would try that, using cloth on the vise jaws to prevent abrasion.

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                            • #15
                              Originally posted by Dimal View Post
                              Using a short handled ~9.0mm artist brush is what I use and it gets right into the thread valleys without problem.
                              The dry Teflon based lubes use a solvent carrier that evaporates very quickly, and leaves the lube behind...

                              Mal.
                              Hi Mal- I believe a pointed metal instrument may be more suitable in case the threads have been crossed. Running the point through the original threads could help to reinstate the original running lines if the cross threading is not too bad. That’s what I read on another forum anyway where some guy had thought his grinder was not salvageable and he took it to an experienced tech who had it back to normal in no time at all using that method.

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