# Grinder Problems - can anyone help?



## ohms (Jan 22, 2018)

I'm posting this here, as my other thread in the Eureka area is a little dead! (https://coffeeforums.co.uk/showthread.php?43057-Burrs-touching-to-get-a-fine-enough-grind)

If you've been following - I've discovered that my Mignon II's burrs don't seem to be parallel. I'm getting a chirp when zeroing them out, but it seems to be 'catching' the top burr more on one side than the other, when I turn the bottom burr by hand. I've tried shimming the other side to this high spot, but to no avail so far. So, I'm putting it out there to anyone who might know more than me! What am I doing so wrong?

In this video i'm turning the adjustment dial so the burrs touch (hard with 1 hand, my apologies!) and then grinding from there so you can see my 'finest' grind available. As it may or may not be visible, the grind is way too coarse. I'm getting a 18g > 40g in 15 seconds.











I did shim the bottom burr to reduce the perceived unevenness of the bottom burr, but if anything, it's worse now than it was. At a loss, here!


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## 4085 (Nov 23, 2012)

have you tried reversing the burrs in case the bottom one has a fault? I cannot think what else it might be. Presumably it is not in warranty still?


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## ashcroc (Oct 28, 2016)

How old are the burrs?


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## ohms (Jan 22, 2018)

dfk41 said:


> have you tried reversing the burrs in case the bottom one has a fault? I cannot think what else it might be. Presumably it is not in warranty still?


No, as I read somewhere that the Mignons burrs shouldn't be reversed? (May have been absolute nonsense, but y'know..)



ashcroc said:


> How old are the burrs?


They're unused! The machine was an ex-demo unit sitting in a shop. When I bought it a couple of weeks back there had been no coffee run through it at all.


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## 4085 (Nov 23, 2012)

I would contact the retailer as it must be covered with warranty. Does not matter what you paid for it if it does not work. Also, never heard that Mignon burrs cannot be reversed but am quite happy to be proved wrong!


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## ohms (Jan 22, 2018)

dfk41 said:


> I would contact the retailer as it must be covered with warranty. Does not matter what you paid for it if it does not work. Also, never heard that Mignon burrs cannot be reversed but am quite happy to be proved wrong!


Not sure if you remember - but I purchased it from a local over Gumtree. Being a "as new" item, I wasn't overly worried about it not working! As as it was all pretty much untouched (it still had it's plastic wrap on) I'm slightly surprised by the issues!


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## 4085 (Nov 23, 2012)

Maybe give a Mignon retailer a ring and ask for mercy to see if they have any ideas. Short of being able to measure run out etc I do not see what you can do


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## ohms (Jan 22, 2018)

dfk41 said:


> Maybe give a Mignon retailer a ring and ask for mercy to see if they have any ideas. Short of being able to measure run out etc I do not see what you can do


Yeah i've been in contact with Bella Barista to see if they can help. Not sure what to do either..! I was hoping there was someone local to me who has maybe had experience of similar!


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## joey24dirt (Jan 28, 2017)

What area are you in?

Can you add some photos of the burrs and how they mount just so I can see how it's set up 

Not that I'm an expert or anything, more that I'm interested to see if I can offer any help


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## ohms (Jan 22, 2018)

joey24dirt said:


> What area are you in?
> 
> Can you add some photos of the burrs and how they mount just so I can see how it's set up
> 
> Not that I'm an expert or anything, more that I'm interested to see if I can offer any help


Area? This one.. (Disclaimer: not my car, I merely drove past this today!)









This is the upper burr which sits on the top plate:









This is the lower one, which is what adjusts.


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## joey24dirt (Jan 28, 2017)

ohms said:


> Area? This one.. (Disclaimer: not my car, I merely drove past this today!)
> 
> View attachment 32554
> 
> ...


By area I just mean where do you live? Then you will know if there is anyone local to help 

Quite a bit of snow wherever it is lol.

Do you have a straight edge, steel rule or something that you know is flat to make sure there's nothing slightly bent? Did you say this happened suddenly?


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## jeebsy (May 5, 2013)

Machina in Edinburgh sell a lot of Eureka, maybe speak to them?


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## DavecUK (Aug 6, 2013)

I watched the videos and read both threads. Just a few suggestions, I am going to assume nothing, apart from that you are using fresh coffee and have basic experience with a grinder and prosumer machine.

1. Mark one burr with marker pen (say the bottom burr) and run them till they touch. You should....you should see witness marks. Then repeat again pressing down on the top plate and the witness marks should increase in length around the burr. If you don't see these wintness marks (which I think you said?), then there is a big question here of what is it you are hearing?

2. The bottom burr might be mounted slightly wrong and need shimming (sounds like you tried that) and it didn't help?

3. The motor burr assembly might be parallel in a straight line to each other, but not to the top burr. in this case shimming the bottom burr won't really achieve much.

4. Shimming the top burr plate would be my favourite to try. It's where the biggest potential for problems is, because of the way it's mounted. Also if the lower burr combination is parallel to each-other, but mounted out of true, it will help.

5. If both burrs are not mounted true, then both might need to be shimmed.

The fact that pressing on the top plate changes the sound indicates definite movement potential on that burr and a mounting issue related to the top plate...I didn't see photos of the interior and burrs of your grinder....that might be useful to post.


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## StuartS (Jan 2, 2015)

The first video clip clearly shows something is not right. You have only backed off a fraction and the grind is way too coarse.

I would remove the top and bottom burrs (from the carriers) and make sure there is nothing preventing them from seating properly. Also check the top plate around the screw holes for any rough edges - same with the bottom casting around the screw holes. When the top is screwed down it shouldn't move relative to the bottom casting and I believe the motor is fixed to this casting so everything should be held together i.e. pressing down on the top plate shouldn't move the top burr relative to the bottom burr, which suggests something is preventing them from seating fully.


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## dsc (Jun 7, 2013)

Could you post some photos showing the adjustment mechanism? I'm guessing it's a worm gear kind of arrangement, but I'm not sure if there's any springs in the system which push the upper burr upwards like in a Mazzer for example (every thread will have some slack in it and springs are typically used to get rid of it, if there's not springs the slack will be taken out by beans during grinding as they push the burrs apart as much as possible, but when there amount of beans inside the burr chamber drop, they will drop back down partially which is of course not so great for grind evenness).

If this was purchased new I'd return it and start looking for a better replacement (ie. better grinder). If it was purchased used, still try and return it as it's not really fit for purpose regardless of what the seller might say (ie. it worked with my charcoaled coffee blends). If you are stuck with it, there's ways to measure things, but it will cost you a £20-30 to get some measuring equipment and even when it's all shimmed, it still might perform far from perfect due to other reasons (shaft runout or part assembly issues).

T.


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## 4085 (Nov 23, 2012)

It was bought from a classified advert so I doubt there will be any come back to the seller.


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## ohms (Jan 22, 2018)

So, an update. I've been at this most of the night and I'm slightly at a loss. So, I took everything apart again and cleaned everything so we had zero pieces of dust or coffee grind.









Checked the burrs all the way around - doesn't seem to be any gaps or undulation:









Top plate looks fine, nothing protruding, which would cause the plate to rock:









Then, using a marker I marked up the bottom burr, which gave me this (you can see a small high spot at the 12:30 position):









I then systematically continued until I had fairly even markings across the burr:









By this point I had put a LOT of foil shims beneath this burr, way, way more than I thought i'd have to. As a result, at this point my adjustment dial was near the end of it's range (at the coarse end), meaning when dialling it towards the fine I was touching burrs super quickly (leaving me no room for a fine grind).

So, I had a look at the top burr.

I'll continue in the post below, as the forum doesn't allow any more photo's per post...


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## ohms (Jan 22, 2018)

So, same process and I got that burr to fairly evenly mark against the bottom one, which left me with this:









All good, I thought. So I put everything back together and put some beans through it. Took the grinder to touching point and backed off a mm or two. No joke, this is the grind I got.









What the hell. At this point, my adjustment on the dial had left me no room whatsoever - as I presume my continual shimming had brought them too close together....?! I honestly don't know. I figured I maybe had just put too many in the bottom one & it was the top I needed to sort out. So, I took the shims out the bottom burr and tried to sort the top.

Marked up, shimmed up.. I can hear the burrs in the grinder churning away, rubbing each other and the only witness marks I get on the top burr is this. (Basically nothing. A tiny kiss at the 12 o'clock position) How can this be? I could feel the grinder vibrating as the burrs touched, it was oh so loud!









As a side note, I've enclosed a video I took when I was shimming the bottom burrs, where you can clearly hear the burrs only touching for a small portion of the rotation:











At this point (4am) I gave up. I understand nothing any more. Bed time.


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## jimbojohn55 (Jan 15, 2016)

my dog woke me up at 4.10am barking as it could smell left over chicken in the kitchen ................. anyway

I would sudgest that the shimming of the bottom burrs has created an uneven wobble in the motor - prob best remove them

next I would look very closely at the mating surfaces of the top burr carrier and the chassis - look for any raised swarf around the bolt holes that might stop it fitting flush - remove with a large drill bit by hand- when remounting finger tighten the bolts then tighten each 1/2 turn at a time.

.

Start over with the marking up

The burrs themselves look a bit cack - the manufacturing quality is suspect might be compatibles or if 8mm thick they are the wrong ones- I can see swarf around the screw holes - are they genuine? should be 7.5mm by 50 x 30

only £17 for a genuine set - email them first and check that they are genuine and not compatibles https://www.theespressoshop.co.uk/en/Eureka-Mignon-MCF-Grinder-Burrs-RH-50x30x75mm---MAC50/m-3406.aspx

If you can still change the sound on the grinder by pressing on the top plate then something is wrong, although its supposed to be new and a shop demonstrator it may have been ham fistedly adjusted and the burrs slammed into each other to demonstrate the chirping noise - the mignion has been a very popular machine as it fills a market spot, I worry about production quality when they have ramped up to meet demand.

nuclear option twist your own arm and upgrade


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## DavecUK (Aug 6, 2013)

In the 2nd from last photo you say you could hear the burrs touching and yet no real marks on the top burr. I would suggest that perhaps something else is touching within the grinder as you close it up. If you remove the top plate and wind the adjuster can you see the burr carrier moving much. In the Mignons it's like 12 or more turns from fine to coarse. I wonder if the burr carrier is moving freely through it's full travel (which from memory is 20+ turns). Remove all the shims from the burrs.

Also with the top burr carrier off, wind the lower burr up as fine as you can get it...do you hear any strange noises. First try turning by hand always before you try under power. By hand it should move freely.

It really sounds as if that lower carrier is not moving up as far as it should. You shimming the bejesus out of it is simply allowing the burrs to get close making up for the adjuster not moving the lower burr up as far as it should. I'm wondering if the noise you hear is actually something else touching where you cant see.


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## StuartS (Jan 2, 2015)

Here is an exploded view of the Mignon: https://goo.gl/images/tQUhU4

If the link doesn't work, just type Eureka Mignon Exploded View into google.

The top burr carrier is very simple - it just bolts to the grinder body casting with three screws. If this burr and carrier is clean, it sits in one position relative to the body. Clearly, pressing on the top plate should not affect the grind because you are not actually moving anything - unless it is rocking somehow (rule this out by cleaning up the mating faces).

The bottom burr carrier is fixed to the motor shaft with a central nut and the burr is fixed to the carrier by three screws. For there to be burr misalignment, it must be created by the motor. Grind adjustment is by moving the motor up or down although I don't know how this adjuster is designed, the motor must be held in a vertical guide somehow.

I think you need to get to the motor now and see if anything that should be holding the motor vertical is broken or bent - the grinder could have been dropped at some point and damaged the internals.

A bent motor shaft is unlikely as it would need a lot of force.

I can't tell the condition of the burrs or whether they are Eureka parts but I also doubt its the burrs.


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## StuartS (Jan 2, 2015)

mmm.... I could be wrong about how the bottom burr is moved although it is fixed to the motor shaft. The exploded view doesn't show the adjuster clearly.

I also think Dave C could be right about something preventing the lower burr from moving up and the noise coming from somewhere below the burrs.

Anyway some open heart surgery is required...


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## ohms (Jan 22, 2018)

With regards to the top plate making noise as I press - that was simply down to the far right lug hole - it's thread can barely grab the screw. I've ordered an M4 rethreading tool to sort that out, so in the mean time i've been using some PTFE tape in the hole to make sure it closes tightly (that's what you can see in the photo). I'm honestly not sure how the burr moves, but I took off the bottom plate to make sure everything underneath looks A-OK.. seems absolutely fine to me. Nothing out of place or loose.









The burrs are original Eureka parts (they have the Eureka markings on them) and when I first removed them from the assembly you could feel I was removing the screws for the first time (they have that sort of "new tightness" like you're breaking the seal). I've taken the shims out and i'm going to screw it all together and see how much rotation I get from top to bottom. It's the touching of burrs (like you can see in the video at the end) that's stopping me from turning to the point where I can no longer do so, by hand. Seems like there's an extreme high spot.

Honestly, I don't see what else could be rubbing other than the burrs, though - there isn't much in there!


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## ohms (Jan 22, 2018)

jeebsy said:


> Machina in Edinburgh sell a lot of Eureka, maybe speak to them?


Yeah I have, only they said they can only repair grinders purchase from them directly. I asked for advice, but I was told to have a look "on the forums" *shrug*

Here's a video of the bottom burr and carrier with no shims - runs cleanly and with no noise..


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## StuartS (Jan 2, 2015)

The photo from the bottom confirms that the motor is raised and lowered to adjust the grind - see the pivoting bar.


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## DavecUK (Aug 6, 2013)

ohms said:


> Yeah I have, only they said they can only repair grinders purchase from them directly. I asked for advice, but I was told to have a look "on the forums" *shrug*
> 
> Here's a video of the bottom burr and carrier with no shims - runs cleanly and with no noise..


Is that up as far as it can go?


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## ohms (Jan 22, 2018)

Update: I've gotten back in touch with the seller and he's offered a refund - I plan to meet him tonight. He's willing to try and repair it himself. I've shown him this thread too and suggested he joins - hopefully we'll see a conclusion to this...


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## dsc (Jun 7, 2013)

StuartS said:


> The photo from the bottom confirms that the motor is raised and lowered to adjust the grind - see the pivoting bar.


Exactly that, seems like there maybe some kind of range adjustment on the bar itself (see the nut under the earthing cable in the bracket holding the non-pivoting end of the bar) which allows for re-zeroing of the adjustment mechanism?

You'll really need a DTI to check if the bottom plate runs true or not, you won't be able to see 0.1mm runout unless you are Superman









If it was me I'd focus on the top burr mount as the one having alignment issues. The bottom burr plate sits on the shaft which sits in two (or more) bearings on the motor, unless it's been banged during installation I can't really see it having runout issues. The top plate though is a different story, it's a loose element which mounts onto the burr chamber and it can introduce loads of errors.

T.


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## El carajillo (Mar 16, 2013)

ohms said:


> So, an update. I've been at this most of the night and I'm slightly at a loss. So, I took everything apart again and cleaned everything so we had zero pieces of dust or coffee grind.
> 
> View attachment 32625
> 
> ...


In the second photo up, is there something in or broken off in the hole at app 8 oclock ?? Allowing the top section to move under pressure ?


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## ohms (Jan 22, 2018)

El carajillo said:


> In the second photo up, is there something in or broken off in the hole at app 8 oclock ?? Allowing the top section to move under pressure ?


Nah, that's just some PTFE tape, which was taken out after.


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## StuartS (Jan 2, 2015)

ok FWIW, i just had my Mignon apart for a clean. Took a couple of measurements with a digital calliper (hand held, so not 100% accurate)

9.03mm from the top plate mounting face to the top burr outer surface.

9.16mm from the inner casting top face to the bottom burr outer surface.

So when clamped together there is a gap of 0.13mm between the burrs.

Holding a straight edge across the casting face, I reckon there is a 1mm gap between this and the top edge of central nut.


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## ashcroc (Oct 28, 2016)

ohms said:


> Update: I've gotten back in touch with the seller and he's offered a refund - I plan to meet him tonight. He's willing to try and repair it himself. I've shown him this thread too and suggested he joins - hopefully we'll see a conclusion to this...


That's good news. There's a Mahlkonig Vario in the for sale section if you're looking for a replacement. Might be a mignon or 2 there too.


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## ohms (Jan 22, 2018)

ashcroc said:


> That's good news. There's a Mahlkonig Vario in the for sale section if you're looking for a replacement. Might be a mignon or 2 there too.


That's the question now - what the hell do I replace it with! I don't know much about the Vario (if anyone has any advice for something up to the £300 mark, let me know...)


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## Jony (Sep 8, 2017)

If you have £300 buy a new mignon?


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## Tsangpa (Nov 26, 2017)

ohms said:


> That's the question now - what the hell do I replace it with! I don't know much about the Vario (if anyone has any advice for something up to the £300 mark, let me know...)


If you still want a mignon there's one in the for sale section in SW Scotland £230 still with BB warranty and a spare set of burrs https://coffeeforums.co.uk/showthread.php?43252-Eureka-mignon-mk2


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## ohms (Jan 22, 2018)

Jony said:


> If you have £300 buy a new mignon?


Yeah I'm tempted to do so - with the new one coming out now too. Just thought I'd see if there were any decent alternatives out there!


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## Tsangpa (Nov 26, 2017)

ohms said:


> Yeah I'm tempted to do so - with the new one coming out now too. Just thought I'd see if there were any decent alternatives out there!


There's a Mazzer Super Jolly for £240 ish which is leaps and bounds ahead of the mignon if you've got room https://coffeeforums.co.uk/showthread.php?42753-2014-Mazzer-Super-Jolly-timer


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## ashcroc (Oct 28, 2016)

Tsangpa said:


> There's a Mazzer Super Jolly for £240 ish which is leaps and bounds ahead of the mignon if you've got room https://coffeeforums.co.uk/showthread.php?42753-2014-Mazzer-Super-Jolly-timer


 About £60 more would get you a Major if space isn't an issue.


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## ohms (Jan 22, 2018)

Space is most definitely an issue! I needs to fit under a kitchen cabinet..


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