# Question about Iberital MC2 - fine grind/over-tightening



## nick_l (Apr 13, 2013)

Hello, I'm new to this forum so if I'm posting this in the wrong place, please let me know... don't want to annoy people straight away by breaching forum etiquette! I'm also quite new to the whole espresso at home thing, so apologies if my question is that of a simpleton.

I recently bought an Iberital MC2 grinder (timer version), and have been trying find an appropriate grind for espresso, using with a Gaggia Classic. This is my first burr grinder. On the Happy Donkey website, from where I bought the grinder, there's a warning about over-tightening the grinder being viewed by the company as invalidating the warranty. My question is, how would I know if the burrs were in contact with one another, and thus were being damaged?

Last week I was getting an 18-20sec extraction from a 14g double dose. Not very good, but I'm really concerned because today I've been getting a 12sec extraction (hadn't adjusted the fineness from last week initially), and have probably tightened the grinder by more than 10 full turns of the control knob with no discernible effect on the length of extraction. By eye and touch, there also doesn't seem to be much difference in the fineness of the grind, but couldn't swear to this. I haven't been aware of any significant-sounding differences in the noise the grinder was making that would suggest damage to the burrs, and I can't see any sign of this. That said, not sure if I know what to look for. I'm assuming contact would be happening at the bottom of the conical burrs, so not sure if I would see any damage by looking in the top. Obviously, nothing dramatic, such as the burrs meshing and jamming, has happened. There doesn't seem to be a point at either end of the fineness scale at which the adjustment knob stops turning, so it seems to be quite difficult to know whether I'm at maximum or minimum fineness.

As a complete novice, any advice would be gratefully received.


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## Glenn (Jun 14, 2008)

Hi Nick and welcome to Coffee Forums UK

This is a good question.

You will hear the burrs meshing together and the motor will (usually) start to labour before you get to that point.

Always try and micro adjust with the grinder running so that you can hear this.

14g is a low dose these days.

Try using 15g before adjusting too much more.


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## El carajillo (Mar 16, 2013)

This may sound scary/ technical but it is not.

Unplug grinder and empty beans. Remove hopper . Squeeze the plastic cover that the hopper sits in and it will lift off (there are small plastic tags that hold it to the metal body)

You will now see a large black gear and at the back a brass worm gear engaged in the teeth of the black gear . Use a coloured pencil to mark the black gear and a point on the brass worm

(THIS IS ONLY A REFERENCE TO SEE HOW MUCH YOU HAVE ADJUSTED IT AFTERWARDS)

Undo the two screws holding the worm gear carrier and lift it out.

You can now unscrew the large black gear to clean out the coffee grounds

Screw the black gear back gently down until it just touches the bottom burr THEN back it off 90degrees (1/4turn) this will give you the base setting for espresso coffee.

Re position and fix the worm gear ,Replace the plastic cover and the hopper.

You will now have a reasonable setting for espresso grind.

THIS MAY SOUND TECHNICAL?DIFFICULT BUT IT IS NOT

This can also be used when you want/need to deep clean your grinder.


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## aaronb (Nov 16, 2012)

As Glenn said you will hear the motor change pitch when the burrs get too close, it will sound laboured. There is a video on youtube of how to calibrate a Vario, whilst not an MC2 it might be worth a watch if you want as you can hear the sound change.

What machine are you using, and what beans? The reason I ask is if its a Gaggia Classic or similar and has a pressurised basket, you can adjust the grind loads and you wont notice much difference in shot time. This has caught people out before! Also if the beans are supermarket beans that have been sat on the shelf for a while, or are older than maybe 4 or 5 weeks from roasting then you may struggle to get a 27 sex extraction. Having to tighten the grinder every few days is natural, but it shouldn't need a massive adjustment.

14g is very low, I'd consider going up to 16g to be honest.

Hope this helps a bit.


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## nick_l (Apr 13, 2013)

Thanks very much to you all for your advice, I haven't had chance to act on any of it yet but will have a go this weekend...

aaronb, I am using a Gaggia Classic, but have replaced the pressurised baskets that came with it with a standard one. The beans were a bag that Happy Donkey packaged with the grinder.


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