Eureka Mignon Specialita burr alignment

Grinders are one of the keys to exceptional espresso. Discuss them here.

#1: Post by tonezone6 »

Few months ago I purchased a Mignon Specialita grinder to use it for my daily espresso.

After a lot of experimentation with different fresh roasted beans from some local roasters, distribution tools, tampers I've reached the conclusion that I cannot get decent espresso results. I replaced few espresso machines from Sage Barista Express to Gaggia Classic and lately I've bought a Sage Dual Boiler.

But the results are not better and what I found when I opened the Specialita to clean it up this days was that the bottom burr is off-center when rotating. So, I suspect that is the issue and I'm attaching below 2 short movies.

I tried also the marker test but when I adjust the grinder gradually to the zero point, which in my case is around 5 on the dial and I'm hearing the chirping, the marker area looks untouched. I will try to do the same on the upper burr in order to se the result.

This morning I checked the upper burr using a whiteboard marker and below is the result. But I don't think I will be able to align them with that bottom burr off center... also notice the contact area which is on the very edge of the top burr and not on the whole flat side. ... ... 0.MOV?dl=0


#2: Post by Noplacetobe »

Looking @ the first movie :shock: I can only conclude : " some fine Italian craftsmanship " :cry: But on a serious note, I would start to center the bottom and top burr with the use of some shims, and only in a later stage try to line the burrs out in the other direction by rotating the top part 120 degrees until it is more or less ok.


#3: Post by thoang77 »

Assuming the two faces are machined quite flat, the marker rub being at the very edge would imply they're fairly unaligned (in terms of parrallelism). Imagine two sharp squares pressed against eachother, now lift up one side of the top piece. Only the far edge of the bottom one will be in contact unless you deform one of the flat surfaces.

Shim that entire burr aside from that one end, probably at least 2-3 foils thick on the far side, 1-2 on the adjacent sides. I had great results after realigning my spec.

tonezone6 (original poster)

#4: Post by tonezone6 (original poster) »

Thanks, but I think shimming without centering the rotation of the bottom burr (check the clip) will be almost an impossible task. And I don't know if can be centered easily at home.


#5: Post by Odie »

Nothing upsets me more then a bad aligned nice grinder.
Have you ever disassembled the bottom burr? And how is the ink test result of the bottom burr, have any photo?
In your case, motor shaft is ok but unfornutaly bottom burr or its carrier seems problamatic. In order to correct troubleshooting you may disassemble the bottom burr and run the motor wihtout it, and visually inspect as like you did at first video.
I had a specialita once, also mine had misaligment problem. I tried to elemite it by shims and ink tests, it took many hours, but at the end I got nothing. After I returned specialita to reseller and I got a XL. Luckly It works perfectly so far.

tonezone6 (original poster)

#6: Post by tonezone6 (original poster) »

Yes, it is/was very frustrating for a beginner like me.
Like i said, i changed a lot of things to get here and i didn't suspect the grinder.
I blamed the pressure in my Gaggia Classic or the shot temperature until recently.


#7: Post by thoang77 »

tonezone6 wrote:Thanks, but I think shimming without centering the rotation of the bottom burr (check the clip) will be almost an impossible task. And I don't know if can be centered easily at home.
Im not sure I'd say it's impossible. Shimming to improve parrallelism has little to do with the centering of the burr/carrier. Concentric (burr/motor runout) and coplanar (parallel) are independent of one another and coplanar makes significantly more of an impact than concentric in terms of achieving an even grind. The way the burrs are designed, that flat face extends out a mm or so, giving you some lateral wiggle room while still having flush flat area to flat area contact, provided they're parallel to one another.

That said, it would be interesting to see that video without the burrs installed. Curious to how much the slight play of the burrs is exacerbating the situation. It could be as simple as loosening the screws on the bottom burr and shifting it a hair.

tonezone6 (original poster)

#8: Post by tonezone6 (original poster) »

I didn't make a movie but I saw that after removing the bottom burr, the burr holder is the one shifting.
So that holder is the problem, not the burr itself.


#9: Post by veuncent »

I have the same problem where the base of the bottom burr is off center. It wobbles, but only slightly (much less visible than the OPs video. Were you able to solve this? Does it make trying to align the burrs horizontally with shims a futile exercise? I had no luck so far.

Edit: my main problem is that I cannot grind fine enough for decaf espresso.