# Grinder problems - eureka mignon



## haz_pro (Apr 4, 2013)

Hey all,

As I mentioned previously on here, when you get to very fine settings on my mignon the burrs touch for about 60 to 70 degrees of a rotation.

I haven't needed to go that fine yet, but I may need to at some point so I am trying to eradicate this issue.

Does anyone have any ideas on what could be. Causing this?

Thanks,

Harry


----------



## coffeechap (Apr 5, 2012)

It can only be a slightly warped motor pin I.e. the pin that protrudes into the burr assembly or the bottom burr assembly plate is very slightly buckled.


----------



## haz_pro (Apr 4, 2013)

Ah that is a pain; both things that can't be easily fixed then. I will just have to hope I don't need to go down to that fine of a grind for now.

Thanks.


----------



## shrink (Nov 12, 2012)

only other thing i could think would be a bad casting on the burrs, they may not be seated properly on the bottom or top set.

I take it you've had the burrs out of the machine and checked for any defects?

could even be as simple as someone having not seated the bottom burr correctly when putting together!


----------



## coffeechap (Apr 5, 2012)

I think he checked tat when he reassembled it shrink so might be something a little more complicated to rectify


----------



## garydyke1 (Mar 9, 2011)

Is this rubbing happening and you are still way off the zero point?

When burrs touch (ie zero) you get a 'chirp' when running , the contact wont be 360 as allignment is never that perfect


----------



## coffeechap (Apr 5, 2012)

Agreed but should be around 90 % at worst 60 percent might even be producing uneven grind


----------



## garydyke1 (Mar 9, 2011)

For sure. Shouldnt be anywhere near zero point unless very very low dose


----------



## El carajillo (Mar 16, 2013)

Can you borrow/ hire a dial test indicator to check for throw/wobble on the spindle. At least you would know where the problem lies.


----------



## haz_pro (Apr 4, 2013)

Thanks for the replies all.

I will take a look at the grinder again later and make sure everything is seated properly.

I had thought about the spindle being bent, or an area of the spindle being "closer" then the rest of the burr, but I had the following thought... Assuming the spindle is bent, or a part of the burr is higher then the rest, wouldn't this cause constant friction as the burrs spin, rather than just on a section of the rotation?

I will look into the dial test indicator, this hasn't caused any issues yet though so I'll see.


----------



## 4085 (Nov 23, 2012)

did you buy it through ebay and recently? If so, have a go back at the seller


----------



## haz_pro (Apr 4, 2013)

dfk41 said:


> did you buy it through ebay and recently? If so, have a go back at the seller


Yeah through eBay from a seller who has been selling a lot of these recently (possibly dodgy some would say). It isn't too recent and I believe in sold as seen so I wouldn't want to go back to him.

I just took the grinder apart and it seems that one of the holes on the lower burr carrier may be stripped.

I have no idea how/where I would get a burr carrier as there isn't a distributor in the UK. Is the grinder safe to use as is for now, or not? I have removed the screw from the stripped hole.

Thanks,

Harry


----------



## 4085 (Nov 23, 2012)

Bella barista are dealers for these


----------



## Mrboots2u (May 10, 2013)

Looking a eBay policy ( link below ) sold as seen , doesnt't actually legally mean a lot.

http://www.ebay.co.uk/gds/Sold-as-seen-as-is-no-returns/10000000002394120/g.html


----------



## 4085 (Nov 23, 2012)

If you bought the grinder through ebay, and did not buy it outside of ebay, then you have full protection as they sell these machines as Used,

Used: An item that has been previously used. The item may have some signs of cosmetic wear, but is fully operational and functions as intended. This item may be a floor model or an item that has been returned to the seller after a period of use. See the seller's listing for full details and description of any imperfections.

So, if it is duff, go through the channels, but i suspect you chose to purchase outside of ebay. I would still get back in touch as they may say they will swop them as they are selling loads of them


----------



## haz_pro (Apr 4, 2013)

Hey all,

Well I just tested the burrs touching with my fingers (rather than motor running) and it is quite bad at the moment, definitely won't be grinding fast enough for espresso. I will get in touch with bella barista to see if I can get another burr carrier, if not I may be in trouble.

As you say I did purchase outside of eBay, completely forgot!

Also forgot to mention there does seem to be some damage on the outside of the bottom burr.

What a pain eh!


----------



## rodabod (Dec 4, 2011)

You might be able to re-tap the hole on the burr carrier for a larger metric thread.


----------



## haz_pro (Apr 4, 2013)

rodabod said:


> You might be able to re-tap the hole on the burr carrier for a larger metric thread.


I hadn't thought about that, may be worth a shot!









I have contacted bella barista and the bloke said he would look into it for me, will see how this goes first.


----------



## El carajillo (Mar 16, 2013)

When you removed the lower burr carrier did you lock it by inserting a screwdriver down the side to hold it ??If so it is possible that applying pressure from one side has bent/deformed the spindle ?? Hope this is not the case . The dial gauge would show this up, also mounted vertically you could test for rise and fall on the carrier. Hope this helps.


----------



## haz_pro (Apr 4, 2013)

El carajillo said:


> When you removed the lower burr carrier did you lock it by inserting a screwdriver down the side to hold it ??If so it is possible that applying pressure from one side has bent/deformed the spindle ?? Hope this is not the case . The dial gauge would show this up, also mounted vertically you could test for rise and fall on the carrier. Hope this helps.


I did use a screwdriver, but I did not try too hard as I was worried about damaging anything so I would be surprised if I had exerted enough pressure to bend the spindle. Who knows though, maybe the spindle is weaker then I think?

I will look into the dial gauge, I had never even head of them before.


----------



## GlennV (Mar 29, 2013)

haz_pro said:


> I just took the grinder apart and it seems that one of the holes on the lower burr carrier may be stripped.


It's very easy to strip the burr carrier threads by over tightening - the burrs are often held by a steel screw into a (soft) aluminium burr carrier - they should just be nipped up. If the lower burr is only held on by two out of the three screws, then it will be sitting slightly high on the side without the screw. I wouldn't go looking for a dial gauge yet.


----------



## glevum (Apr 4, 2013)

This seems to be happening quite a bit at the moment. Will encourage me to be gentle with the screwdriver after a burr clean


----------



## GlennV (Mar 29, 2013)

There are lots of things to be wary of when opening up grinders. For example, motor start capacitors can charge to a potentially lethal 600V or so, and retain that charge after days or even weeks of non use. Until you've discharged any capacitors (through a resistor), and checked with a multimeter, then all circuitry should be regarded as live even if the grinder is not plugged in. 600VDC shocks are nasty.


----------



## glevum (Apr 4, 2013)

I never go past the burrs....have no need to. Great advice. Cheers Glenn


----------



## Roopster (Mar 21, 2013)

I think my lower burr carrier has one thread stripped as well, but after I cleaned it out it is holding OK with no touching of burrs that you report so I've left it. I did contact Elektro's in Italy about spares and Gianni there was very helpful. If you need it the part is 15800044 lower grinder support with 3 holes € 21,00 and about 9 euro postage so not a nightmare hopefully!


----------



## Roopster (Mar 21, 2013)

[email protected]


----------



## bernd (Feb 2, 2017)

I had the problem with my Mignon, that I was not able to reach an extraction time of more than 7-8 sec. For more than one year I used the Mignon together with my Rancilio Silvia without really knowing how to reach something you can call espresso. Never heard about channeling or 25sec of target extraction time.

I just was disappointed by the quality of the coffee. Now I took the time to understand what happens. So after reading the comments on different blogs I quickly came to the conclusion that the milling result was not fine enough. After disassembling the upper burr I recognized that the upper burr only came in touch with the lower burr in an angular area of about 20°. So my conclusion: Complete misalignment of the burrs. So I placed small hard cartoon sheets between upper burr and upper burr holder on the opposite side of the contact zone. I checked the result by cutting a circular cartoon plate which I placed between upper and lower burr and reassembled the upper burr holder (before I've set the milling to rough). Then, without activating the mill, I reduced the milling degree to fine until the burr came in touch and forced lightly in order to get an imprint on the cartoon plate. So I was able to judge quiet precisely the contact area. I needed to put something around 0,6mm!!! below one of the three screws until the alignment was correct. And to my big surprise: The first time since one year I was able to prepare a real espresso with the correct extraction time of 25sec. So at least I understood the problem. But of course this is not a reliable solution. The cartoon plates will settle down and the screwing force risk to relax and the screw risk to loosen what at the end could destroy the burrs.

So finally I'm very disappointed by the production quality of the machine because I'm convinced that this is either a problem of a control of the process parameters which have impact on the alignment or a problem of the concept. At the end: poor engineering work !

It is a question of luck either to have the perfect mill which can mill coffee for the perfect shot or ... to have an awful "sock juice" (as they call it in France)

Perhaps somebody is interested in this experience and can take profit by claiming on time (not like me)


----------



## coffeechap (Apr 5, 2012)

Did you buy the grinder new?


----------



## bernd (Feb 2, 2017)

coffeechap said:


> Did you buy the grinder new?


Yes I bought it new at "maxicoffee.com" in France. But more than a year ago and the result always was quiet similar.

I only found one comment from another person who talked about a similar problem on a blog.

But I can imagine that there are many customer facing similar problems.


----------



## coffeechap (Apr 5, 2012)

Speak maxi coffee explain the problem as there is a defect in the grinder.


----------



## urbanbumpkin (Jan 30, 2013)

Agree with CC. You've been supplied with a defective grinder.

Is it worth not mentioning that the OP has dismantled it?


----------



## urbanbumpkin (Jan 30, 2013)

bernd said:


> Yes I bought it new at "maxicoffee.com" in France. But more than a year ago and the result always was quiet similar.
> 
> I only found one comment from another person who talked about a similar problem on a blog.
> 
> But I can imagine that there are many customer facing similar problems.


Let us know how you get on.


----------



## dsc (Jun 7, 2013)

bernd said:


> I had the problem with my Mignon, that I was not able to reach an extraction time of more than 7-8 sec. For more than one year I used the Mignon together with my Rancilio Silvia without really knowing how to reach something you can call espresso. Never heard about channeling or 25sec of target extraction time.
> 
> I just was disappointed by the quality of the coffee. Now I took the time to understand what happens. So after reading the comments on different blogs I quickly came to the conclusion that the milling result was not fine enough. After disassembling the upper burr I recognized that the upper burr only came in touch with the lower burr in an angular area of about 20°. So my conclusion: Complete misalignment of the burrs. So I placed small hard cartoon sheets between upper burr and upper burr holder on the opposite side of the contact zone. I checked the result by cutting a circular cartoon plate which I placed between upper and lower burr and reassembled the upper burr holder (before I've set the milling to rough). Then, without activating the mill, I reduced the milling degree to fine until the burr came in touch and forced lightly in order to get an imprint on the cartoon plate. So I was able to judge quiet precisely the contact area. I needed to put something around 0,6mm!!! below one of the three screws until the alignment was correct. And to my big surprise: The first time since one year I was able to prepare a real espresso with the correct extraction time of 25sec. So at least I understood the problem. But of course this is not a reliable solution. The cartoon plates will settle down and the screwing force risk to relax and the screw risk to loosen what at the end could destroy the burrs.
> 
> ...


Use metal shims, if need be use some threadlock on the burr bolts to hold it in place. Cardboard is far from ideal as you say, metal won't compress and the bolts shouldn't come loose. If it's indeed as much as 0.6mm that is massive misalignment considering a change of 0.2mm is enough to take you from a gusher to a choker.

First step would be to try and get a replacement or a refund though.

Rgds,

T.


----------

