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Thread: a nut kills grinder

  1. #1
    Senior Member robusto's Avatar
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    a nut kills grinder

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    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. #2
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    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.

  3. #3
    CoffeeSnobs Owner Andy's Avatar
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    Re: a nut kills grinder


    Bugga.

    The Colombian is typicaly fairly clean bean too.


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    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.

  5. #5
    TC
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    Re: a nut kills grinder

    Quote 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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    Re: a nut kills grinder

    Quote 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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    Senior Member julsajet's Avatar
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    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.

  8. #8
    Mal Dimal's Avatar
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    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.

  9. #9
    Senior Member robusto's Avatar
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    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


  10. #10
    Super Moderator Javaphile's Avatar
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    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

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    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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    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!

  13. #13
    Senior Member ozscott's Avatar
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    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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    CoffeeSnobs Owner Andy's Avatar
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    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")
    chokkidog likes this.

  15. #15
    Sleep is overrated Thundergod's Avatar
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    Re: a nut kills grinder

    [s]Nuts![/s]
    Bugger!

    I hope you can replace the worm drive easily.

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    Re: a nut kills grinder

    Quote Originally Posted by Andy Freeman link=1179464792/0#13 date=1179557131
    ...how fast does your Yamaha grind coffee?

    (I am picturing quite a mess and expect you are related to "Tim the Tool man")
    probably just a fraction quicker than your new climax...nice pick up ;)

  17. #17
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    Re: a nut kills grinder

    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.

    Usually with electronic gear it is the other way around.

    I have seen a $10,000 communications controller turn into a bar heater just to save a ten cent fuse.

    But then comms controllers are not much use, they cant grind coffee :o

  18. #18
    Senior Member speleomike's Avatar
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    Re: a nut kills grinder

    Hi all
    This morning I had a stone in some beans for the first time. It was some Costa Rican Tarrazu which I had bought already roasted. Here is the story ...

    My wife knows everything. When I mentioned that this Tarrazu originates in Costa Rica she suggested that the soil was probably from the Arenal volcano.
    http://volcano.und.edu/vwdocs/volc_images/north_america/costa_rica/new_arenal.html
    Its pretty impressive.

    Later that day the grinder made an awfull noise and I turned it off immediately. Tipped everything out and found a small stone about a bean size. Jill looked at it under the microscope and its looks pyroclastic, with small feldspar crystals.
    So she probably has a nice sample from the Arenal volcano thanks to my coffee habit. The grinder is still fine.

    Mike

  19. #19
    Sleep is overrated Thundergod's Avatar
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    Re: a nut kills grinder

    Does Jill like your grinder?
    Im the suspicious type.
    It seems awfully coincidental that she knows so much about the Arenal volcano and the next thing you know theres a piece of it in your grinder. :o

  20. #20
    Senior Member ozscott's Avatar
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    Re: a nut kills grinder

    At 5500 rpm and the full 115 horses released I reckon I could do the entire coffee snobs stock pile in less than 2 minutes!!! I should know better than to use marine/automotive examples on this site!! (even in the presence of several petrol heads)

    Cheers

    PS. If someone wants to donate the new Yammy V8 350 horsepower outboard please send me a PM

  21. #21
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    Re: a nut kills grinder


    Maybe the risk of stones and nuts and other foreign objects in coffee beans can create a demand for the next coffeesnob "must have" accessory. A flat, shallow coffee bean tray, just to visually inspect the beans. The tray will have one end taper shaped into a chute so that the beans can be easily tipped into the hopper without losing a bean. The deluxe tray will have a magnetic base for trapping metallic objects, but this will be more expensive compared to the basic model. The tray will be white in colour, so it makes it easy to spot the foreign object and non stick.

    How does this sound? ;)


    Lawrance




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