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  • a nut kills grinder

    My Iberital grinder has come to an extremely sudden, screeching end. Id barely begun grinding some Columbians from last months batch when it made a high - pitched whining noise and came to a dead stop.

    Its the sort of noise that tells you theres more than a stubborn hard- SO bean at play in the burrs.

    On inspection, there was a square-looking thing wedged in the burrs. I plucked it out:

    A small nut.

    Not the edible or idiotic variety, but the metal ones which screw onto the ends of bolts. Not a bright metal colour, but the same roast grade as the surrounding beans.

    Where it heralds from....? Perhaps deep in the plantations of Colombia.

    But back the grinder. No noticeable broken or mangled teeth, so put back the hopper and beans, and tried again.

    At first, nothing, then a free-spinning motor doing no work .

    Dismantled the grinder, removed the top mounting plate, removed the motor from it....

    To cut a long story short, a large nylon reduction gear has three missing teeth, and trying to separate it from its shaft broke the shaft.

    I really hate paying for someone elses carelessness... Nuts indeed.

    --Robusto


  • #2
    Re: a nut kills grinder

    ouch..too bad about the grinder...time for a Compak

    Yeah...try and go through your greens and pick out shit they missed at origin.

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    • #3
      Re: a nut kills grinder


      Bugga.

      The Colombian is typicaly fairly clean bean too.

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      • #4
        Re: a nut kills grinder

        Bad news there robusto....

        Whilst on our 5 Senses visit the comment about rocks etc in their green beans was raised..... and yes they do get a few (and hopefully remove them all)....

        But the most interesting info was these "optional extras" dont tend to kill the burrs (as I had thought) but more often the motor / drivetrain - especially in domestic machines..... and when this happens the grinder is a "has been" ....

        Better luck with your next one.

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        • #5
          Re: a nut kills grinder

          Originally posted by JavaB link=1179464792/0#3 date=1179466337
          Bad news there robusto....

          Whilst on our 5 Senses visit the comment about rocks etc in their green beans was raised..... and yes they do get a few (and hopefully remove them all)....

          But the most interesting info was these "optional extras" dont tend to kill the burrs (as I had thought) but more often the motor / drivetrain - especially in domestic machines..... and when this happens the grinder is a "has been"   ....

          Better luck with your next one.
          Bummer- perhaps it comes back to the build...A variet of things have found their way through my grinders- Mazzer/Rocky and its grinders 1 - bits and pieces 0....

          Maybe the more expensive stuff is a touch tougher...

          Hope you find a good replacement..

          2mcm

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          • #6
            Re: a nut kills grinder

            Originally posted by 2muchcoffeeman link=1179464792/0#4 date=1179466610
            Bummer- perhaps it comes back to the build...A variet of things have found their way through my grinders- Mazzer/Rocky and its grinders 1 - bits and pieces 0....

            Maybe the more expensive stuff is a touch tougher...
            2mcm
            Yep, Im sure that is correct.... there is nothing even resembling plastic / nylon in the burr assembly, drive train etc on my La Cimbali ( all brass and steel) and the motor is very substantial as well..... probably could chew up and spit out a tree trunk.....

            Im sure Mazzers and the like are similarly robust - and having flat burrs could also be an advantage

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            • #7
              Re: a nut kills grinder

              Damn. That really sucks. Next well be modifying our grinders so they have a built-in metal detector that scans the beans before grinding.

              Hope it doesnt stop your coffee production for too long.

              Comment


              • #8
                Re: a nut kills grinder

                Hmmm, what a bummer Robusto....

                Pity Iberital didnt think to use "shear pins" in critical parts of the drive train to protect against such eventualities, dont know that anything else would provide adequate protection in this instance? As JJ suggests, might have to get a big powerful magnet to troll through the beans before or after roasting in the future, just in case,

                Mal.

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                • #9
                  Re: a nut kills grinder

                  The design problem here is that the motor is quite powerful -- too powerful, and it wasnt going to be stopped because of a foreign object.

                  So it kept spinning, along with the worm drive at the end of the armature.

                  The weak point is the nylon reduction gear. The worm drive spinning fast simply chewed the gear which of course was unable to move because of the nut jammed in the burrs.

                  The burrs came out unscathed. The episode has enabled me to get to know the grinder at close range, having dismantled it , and I must say, for a low - mid- end mill its quite robust.

                  Stones I understand...but metal nuts?

                  A few years back I toured a glass bottle recycling plant. Colours are kept separate, and things like chinaware are a glass recyclers worst nightmare.

                  After the bottles are crushed into small pieces they go along a conveyor belt, but theres always a few blow-ins of a different colour.

                  An optical scanner sees the foreigner, and directs a direct jet blast of air to remove it from the pack.

                  Mmmmm.... could be applied to the coffee industry! Blow out foreign objects before they hit the roaster.

                  --Robusto

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                  • #10
                    Re: a nut kills grinder

                    When I bought my used mazzer super jollys one of them had a 3/4s circle of alum rod with a magnet that could freely slide on it. The piece sits in the hopper and was meant to both break up any clumps of beans and to pull any metals out of them as they flowed by.

                    Assumming the grinders were the same age as the espresso machine they were bought with they would be roughly 20 years old. When I talked to the local Cimbali dealer about it one of the older techs there recognized the part and told me what it was for. Later models had the hoppers modified to break up clumps in a different manner and the magnet was removed because the hardness of the burrs, quality of beans, and the cleaning of the beans of foreign objects at roasters had improved enough that it was no longer considered necessary.


                    Java "Old tech sometimes is best!" phile
                    Toys! I must have new toys!!!

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                    • #11
                      Re: a nut kills grinder

                      http://www.iberital.com/iberital/MOLINOS/IBERITAL.pdf
                      May not be all bad, looks like that large gear is replaceable, may have been designed to be the weak link, to save worse damage to the motor.

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                      • #12
                        Re: a nut kills grinder

                        That is possible. Often better to design a sacrificial part to protect a more complex part. the 4mm guage wire on my cooler catches most small stones and I do a fairly close visual inspection for foriegn objects but I have never seen a nut. Bad luck - I reckon there is a whole insurance field lying open here!

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                        • #13
                          Re: a nut kills grinder

                          If my 115hp Yammaha outboard ever hits an immovable object I want the prop to shear and not the gearbox to explode - hence all outboard either use a shear pin (small older outboards) or rubber hub assembly.

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                          • #14
                            Re: a nut kills grinder

                            ...how fast does your Yamaha grind coffee?

                            (I am picturing quite a mess and expect you are related to "Tim the Tool man")

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                            • #15
                              Re: a nut kills grinder

                              Nuts!
                              Bugger!

                              I hope you can replace the worm drive easily.

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